Priobskoe field where. Geology of the Priobskoye deposit (Priobka). §1.Priobskoye oil field
Priobskoe oil deposit
| §one. Priobskoye oil field. ………………………………… |
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| 1.1. Properties and composition of oil |
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| 1.2. Initial well flow rate |
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| 1.3. Types and location of wells |
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| 1.4. Oil lifting method |
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| 1.5 Collector characteristics |
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| 1.6.MOON, KIN |
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| §2. Preparation of oil for processing……………………………………. |
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| §3. Primary oil refining of the Priobskoye field………. |
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| §four. Catalytic cracking…………………………………………… |
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| §5.Catalytic reforming…………………………………………. |
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| Bibliographic list……………………………………………... |
§1.Priobskoye oil field.
Priobskoe- the largest field in Western Siberia is administratively located in the Khanty-Mansiysk region at a distance of 65 km from Khanty-Mansiysk and 200 km from Nefteyugansk. It is divided by the Ob River into two parts - left and right bank. The development of the left bank began in 1988, the right bank - in 1999. Geological reserves are estimated at 5 billion tons. Proved and recoverable reserves are estimated at 2.4 billion tons. Opened in 1982. Deposits at a depth of 2.3-2.6 km. The density of the oil is 863-868 kg/m3 (the type of oil is medium, because it falls in the range of 851-885 kg/m 3 ), the content of paraffins is moderate (2.4-2.5%) and the sulfur content is 1.2-1 ,3% (belongs to the class of sulphurous, class 2 oil supplied to the refinery in accordance with GOST 9965-76). As of the end of 2005, there were 954 producing and 376 injection wells in the field. Oil production at the Priobskoye field in 2007 amounted to 40.2 million tons, of which Rosneft - 32.77, and Gazprom Neft - 7.43 million tons. The microelement composition of oil is an important characteristic of this type of raw material and carries various geochemical information about the age of oil, formation conditions, origin and migration routes, and finds the most wide application for identifying oil fields, optimizing the search strategy for deposits, separating the production of jointly operated wells.
Table 1. Range and average value of microelement content of Priobskaya oil (mg/kg)
Initial flow rate of operating oil wells is from 35 t/day. up to 180 t/day. The location of the wells is clustered. Oil recovery factor 0.35.
A cluster of wells is such an arrangement when the mouths are close to each other on the same technological platform, and the bottoms of the wells are in the nodes of the reservoir development grid.
Currently, most production wells are drilled in clusters. This is explained by the fact that cluster drilling of fields can significantly reduce the size of the areas occupied by drilling and then production wells, roads, power lines, and pipelines.
This advantage is of particular importance in the construction and operation of wells on fertile lands, in nature reserves, in the tundra, where the disturbed surface layer of the earth is restored after several decades, in swampy areas, which complicate and greatly increase the cost of construction and installation work of drilling and operational facilities. Pad drilling is also necessary when it is required to open oil deposits under industrial and civil structures, under the bottom of rivers and lakes, under the shelf zone from the shore and overpasses. A special place is occupied by cluster construction of wells on the territory of the Tyumen, Tomsk and other regions of Western Siberia, which made it possible to successfully carry out the construction of oil and gas wells on backfill islands in a remote, swampy and populated region.
The location of the wells in the well pad depends on the terrain conditions and the proposed means of communication between the well pad and the base. Bushes that are not connected by permanent roads to the base are considered local. In some cases, bushes can be basic when they are located on highways. On local well pads, as a rule, they are arranged in the form of a fan in all directions, which makes it possible to have the maximum number of wells on a well pad.
Drilling and auxiliary equipment is mounted in such a way that when the drilling rig is moved from one well to another, the drilling pumps, receiving pits and part of the equipment for cleaning, chemical treatment and preparation of flushing fluid remain stationary until the completion of the construction of all (or part) of the wells on this well pad.
The number of wells in a cluster can vary from 2 to 20-30 or more. Moreover, the more wells in the pad, the greater the deviation of bottomholes from the wellheads, the length of the wellbore increases, the length of the wellbore increases, which leads to an increase in the cost of well drilling. In addition, there is a danger of meeting trunks. Therefore, it becomes necessary to calculate the required number of wells in a cluster.
A deep-pumping method of oil production is a method in which liquid is lifted from a well to the surface using various types of rod and rodless pumping units.
At the Priobskoye field, electric centrifugal pumps are used - a rodless deep-well pump, consisting of a multi-stage (50-600 stages) centrifugal pump located vertically on a common shaft, an electric motor (asynchronous electric motor filled with dielectric oil) and a protector that serves to protect the electric motor from liquid ingress into it. The motor is powered by an armored cable, which is lowered along with the pump pipes. The frequency of rotation of the motor shaft is about 3000 rpm. The pump is controlled at the surface by means of a control station. The performance of the electric centrifugal pump varies from 10 to 1000 m3 of liquid per day with an efficiency of 30-50%.
The installation of an electric centrifugal pump includes underground and surface equipment.
The installation of a downhole electric centrifugal pump (ESP) has only a control station with a power transformer on the surface of the well and is characterized by the presence of high voltage in the power cable lowered into the well along with tubing. Highly productive wells with high reservoir pressure are operated by electric centrifugal pump units.
The field is remote, difficult to access, 80% of the territory is located in the floodplain of the Ob River and is flooded during the flood period. The field is characterized by a complex geological structure - a complex structure of sand bodies in terms of area and section, the layers are hydrodynamically weakly connected. Reservoirs of productive formations are characterized by:
Low permeability;
Low grit;
Increased clay content;
High dissection.
The Priobskoye field is characterized by a complex structure of productive horizons both in terms of area and section. The reservoirs of horizons AC10 and AC11 are medium and low productive, and AC12 are anomalously low productive. The geological and physical characteristics of the productive strata of the field indicate the impossibility of developing the field without actively influencing its productive strata and without using methods of production intensification. This confirms the experience of developing the operational section of the left-bank part.
The main geological and physical characteristics of the Priobskoye field for assessing the applicability of various impact methods are:
1) depth of productive layers - 2400-2600 m,
2) deposits are lithologically shielded, the natural regime is elastic, closed,
3) the thickness of the layers AC 10, AC 11 and AC 12, respectively, up to 20.6, 42.6 and 40.6 m.
4) initial reservoir pressure - 23.5-25 MPa,
5) formation temperature - 88-90°С,
6) low permeability of reservoirs, average values according to the results
7) high lateral and vertical heterogeneity of formations,
8) reservoir oil viscosity - 1.4-1.6 mPa*s,
9) saturation pressure of oil 9-11 MPa,
10) oil of the naphthenic series, paraffinic and low-resinous.
Comparing the presented data with the known criteria for the effective use of reservoir stimulation methods, it can be noted that, even without a detailed analysis, thermal methods and polymer flooding (as a method of oil displacement from reservoirs) can be excluded from the above methods for the Priobskoye field. Thermal methods are used for reservoirs with high-viscosity oils and at depths up to 1500-1700 m. higher temperatures, expensive, special polymers are used).
Experience in the development of domestic and foreign fields shows that waterflooding is a fairly effective method of influencing low-permeability reservoirs with strict observance of the necessary requirements for the technology of its implementation. Among the main reasons causing a decrease in the efficiency of waterflooding of low-permeability formations are:
Deterioration of rock filtration properties due to:
Swelling of the clay components of the rock upon contact with the injected water,
Clogging of the collector with fine mechanical impurities in the injected water,
Precipitation of salt deposits in the porous medium of the collector during the chemical interaction of injected and formation water,
Reduction of reservoir coverage by flooding due to the formation of cracks around injection wells - rupture and their propagation in depth
Significant sensitivity to the nature of the wettability of rocks by the injected agent Significant reduction in reservoir permeability due to paraffin precipitation.
The manifestation of all these phenomena in low-permeability reservoirs causes more significant consequences than in high-permeability rocks.
To eliminate the influence of these factors on the waterflooding process, appropriate technological solutions are used: optimal well grids and technological modes of well operation, injection of water of the required type and composition into the reservoirs, its appropriate mechanical, chemical and biological treatment, as well as the addition of special components to the water.
For the Priobskoye field, flooding should be considered as the main treatment method.
The use of surfactant solutions in the field was rejected, primarily due to the low efficiency of these reagents in low-permeability reservoirs.
For the Priobskoye field, alkaline flooding cannot be recommended for the following reasons:
The main one is the predominant structural and layered clay content of the reservoirs. Clay aggregates are represented by kaolinite, chlorite and hydromica. The interaction of alkali with clay material can lead not only to swelling of the clay, but also to the destruction of the rock. An alkaline solution of low concentration increases the swelling coefficient of clays by 1.1-1.3 times and reduces the permeability of the rock by 1.5-2 times compared to fresh water, which is critical for low-permeability reservoirs of the Priobskoye field. The use of solutions of high concentration (reducing the swelling of clays) activates the process of destruction of the rock.
The favorite technology of Russian oilmen is hydraulic fracturing: fluid is pumped into the well under pressure up to 650 atm. to form cracks in the rock. Cracks are fixed with artificial sand (proppant): it does not allow them to close. Through them, oil seeps into the well. According to LLC SibNIINP, hydraulic fracturing leads to an increase in oil inflow at the fields of Western Siberia from 1.8 to 19 times.
At present, oil producing companies, carrying out geological and technical activities, are mainly limited to the use of standard hydraulic fracturing (HF) technologies using a polymer-based gelled aqueous solution. These solutions, as well as killing fluids, as well as drilling fluids, cause significant damage to the formation and the fracture itself, which significantly reduces the residual conductivity of the fractures, and, as a result, oil production. Formation and fracture clogging is of particular importance in fields with a current formation pressure of less than 80% of the initial one.
From the technologies used to solve this problem, technologies using a mixture of liquid and gas are distinguished:
Foamed (for example, nitrided) liquids with a gas content of less than 52% of the total volume of the mixture;
Foam hydraulic fracturing - more than 52% of gas.
Having considered the available Russian market technologies and the results of their implementation, Gazpromneft-Khantos specialists chose foam fracturing and offered Schlumberger to conduct pilot work (PW). Based on their results, an assessment was made of the effectiveness of foam hydraulic fracturing at the Priobskoye field. Foam fracturing, like conventional fracturing, is aimed at creating a fracture in the reservoir, the high conductivity of which ensures the flow of hydrocarbons to the well. However, during foam fracturing, due to the replacement (on average 60% of the volume) of a part of the gelled aqueous solution with compressed gas (nitrogen or carbon dioxide), the permeability and conductivity of fractures increase significantly, and, as a result, the degree of formation damage is minimal. In world practice, the highest efficiency of using foam fluids for hydraulic fracturing has already been noted in wells where reservoir energy is not enough to push the spent hydraulic fracturing fluid into the wellbore during its development. This applies to both new and existing well stock. For example, in selected wells of the Priobskoye field, reservoir pressure decreased to 50% of the original. When performing foam fracturing, the compressed gas that was injected as part of the foam helps to squeeze the spent fluid out of the formation, which increases the volume of the spent fluid and reduces the time
well development. For work at the Priobskoye field, nitrogen was chosen as the most versatile gas:
Widely used in the development of wells with coiled tubing;
Inert;
Compatible with hydraulic fracturing fluids.
After completion of the work, well completion, which is part of the "foam" service, was carried out by Schlumberger. A feature of the project was the implementation of pilot work not only in the new, but also in the existing well stock, in reservoirs with existing hydraulic fractures from the first jobs, the so-called re-fracturing. A crosslinked polymer system was chosen as the liquid phase of the foam mixture. The resulting foam mixture successfully helps to solve the problems of preserving the properties of the prize
combat zone. The polymer concentration in the system is only 7 kg/t of proppant, for comparison, in the wells of the nearest environment - 11.8 kg/t.
At present it can be noted successful implementation foam hydraulic fracturing using nitrogen in the wells of the AS10 and AS12 formations of the Priobskoye field. Close attention was paid to the work in the existing well stock, since repeated hydraulic fracturing makes it possible to involve in the development of new layers and interlayers that were not previously affected by the development. To analyze the effectiveness of foam hydraulic fracturing, their results were compared with the results obtained from neighboring wells in which conventional hydraulic fracturing was carried out. The reservoirs had the same oil-saturated thickness. The actual flow rate of liquid and oil in wells after foam hydraulic fracturing at an average pump intake pressure of 5 MPa exceeded the flow rate of neighboring wells by 20 and 50%, respectively. However, the working bottomhole pressure before the pump in the wells after foam fracturing is on average 8.9 MPa, in the surrounding wells - 5.9 MPa. The recalculation of the well potential for equivalent pressure makes it possible to evaluate the effect of foam hydraulic fracturing.
Pilot work with foam hydraulic fracturing in five wells of the Priobskoye field showed the effectiveness of the method both in the existing and in the new well stock. Higher pump intake pressure in wells after the use of foam mixtures indicates the formation of high conductivity fractures as a result of foam hydraulic fracturing, which provides additional oil production from wells.
At present, the development of the northern part of the field is carried out by LLC RN-Yuganskneftegaz, owned by Rosneft, and the southern part by LLC Gazpromneft-Khantos, owned by Gazprom Neft.
By decision of the Governor of the KhMAO, the field was given the status of "Territory of a special procedure for subsoil use", which determined the special attitude of oilmen to the development of the Priobskoye field. The inaccessibility of reserves, the fragility of the ecosystem of the deposit, led to the use of the latest environmental technologies. 60% of the territory of the Priobskoye field is located in the flooded part of the Ob River floodplain; environmentally friendly technologies are used in the construction of well pads, pressure oil pipelines and underwater crossings.
Site objects located on the territory of the deposit:
Booster pumping stations - 3
· Multiphase pumping station Sulzer-1
· Cluster pumping stations for pumping the working agent into the formation - 10
Floating pumping stations - 4
Oil preparation and pumping workshops - 2
Oil separation unit (USN) - 1
In May 2001, Sulzer's unique multiphase pumping station was installed at pad 201 on the right bank of the Priobskoye field. Each pump of the installation is capable of pumping 3.5 thousand cubic meters of liquid per hour. The complex is served by one operator, all data and parameters are displayed on a computer monitor. The station is the only one in Russia.
The Dutch pumping station "Rosskor" was equipped at the Priobskoye field in 2000. It is designed for intrafield pumping of multiphase fluid without the use of flares (to avoid associated gas flaring in the floodplain of the Ob River).
The drilling cuttings processing plant on the right bank of the Priobskoye field produces silicate brick, which is used as building material for the construction of roads, pad foundations, etc. To solve the problem of utilization of associated gas produced at the Priobskoye field, the first Gas Turbine Power Plant in Khanty-Mansi Autonomous Okrug was built at the Prirazlomnoye field, which provides electricity to the Priobskoye and Prirazlomnoye fields.
The power transmission line built across the Ob has no analogues, the span of which is 1020 m, and the diameter of the wire specially made in the UK is 50 mm.
§2. Preparation of oil for processing
Crude oil extracted from wells contains associated gases (50-100 m 3 /t), formation water (200-300 kg/t) and mineral salts dissolved in water (10-15 kg/t), which adversely affect transportation, storage and subsequent processing. Therefore, the preparation of oil for processing necessarily includes the following operations:
Removal of associated (dissolved in oil) gases or oil stabilization;
Oil desalination;
Dehydration (dehydration) of oil.
Oil stabilization - crude oil from the Ob region contains a significant amount of light hydrocarbons dissolved in it. During transportation and storage of oil, they can be released, as a result of which the composition of the oil will change. To avoid the loss of gas and with it light gasoline fractions and to prevent air pollution, these products must be extracted from oil before it is processed. A similar process of separating light hydrocarbons from oil in the form of associated gas is called stabilization oil. Stabilization of oil at the Priobskoye field is carried out by separation method directly in the area of its production at metering units.
Associated gas is separated from oil by multi-stage separation in gas separators, in which the pressure and oil flow rate are successively reduced. As a result, desorption of gases occurs, together with which volatile liquid hydrocarbons are removed and then condensed, forming "gas condensate". With the separation method of stabilization, up to 2% of hydrocarbons remain in the oil.
Desalting and dehydration oil- removal of salts and water from oil occurs at field oil treatment plants and directly at oil refineries (refineries).
Let's consider the device of electrodesalting installations.
Oil from the feed tank 1 with the addition of a demulsifier and a weak alkaline or soda solution passes through the heat exchanger 2, is heated in the heater 3 and enters the mixer 4, in which water is added to the oil. The resulting emulsion sequentially passes through the electric dehydrators 5 and 6, in which the bulk of the water and salts dissolved in it are separated from the oil, as a result of which their content is reduced by 8-10 times. The desalinated oil passes through the heat exchanger 2 and, after cooling in the refrigerator 7, enters the collector 8. The water separated in the electric dehydrators settles in the oil separator 9 and is sent for purification, and the separated oil is added to the oil supplied to the CDU.
The processes of desalination and dehydration of oil are associated with the need to break emulsions that water forms with oil. At the same time, emulsions of natural origin, formed in the process of oil production, are destroyed in the fields, and artificial emulsions obtained by repeated washing of oil with water to remove salts from it are destroyed at the plant. After treatment, the content of water and metal chlorides in oil is reduced at the first stage to 0.5-1.0% and 100-1800 mg/l, respectively, and at the second stage to 0.05-0.1% and 3-5 mg/l, respectively. l.
To accelerate the process of breaking emulsions, it is necessary to subject the oil to other measures of influence aimed at coarsening water droplets, increasing the density difference, and reducing the viscosity of the oil.
In the Ob oil, the introduction of a substance (demulsifier) into the oil is used, due to which the separation of the emulsion is facilitated.
And for oil desalination, oil is washed with fresh fresh water, which not only washes out salts, but also has a hydromechanical effect on the emulsion.
§3. Primary oil refining of the Priobskoye field
Oil is a mixture of thousands of different substances. The complete composition of oils even today, when the most sophisticated means of analysis and control are available: chromatography, nuclear magnetic resonance, electron microscopes - far from all these substances are completely determined. But, despite the fact that the composition of oil includes almost all the chemical elements of the table D.I. Mendeleev, its basis is still organic and consists of a mixture of hydrocarbons of various groups that differ from each other in their chemical and physical properties. Regardless of complexity and composition, oil refining begins with primary distillation. Usually, distillation is carried out in two stages - with a slight excess pressure close to atmospheric and under vacuum, while using tube furnaces to heat the raw materials. Therefore, installations for primary oil refining are called AVT - atmospheric-vacuum tubulars.
The oils of the Priobskoye field have a potentially high content of oil fractions, therefore, the primary oil refining is carried out according to the fuel-oil balance and is carried out in three stages:
Atmospheric distillation to obtain fuel fractions and fuel oil
Vacuum distillation of fuel oil to obtain narrow oil fractions and tar
Vacuum distillation of a mixture of fuel oil and tar to obtain a broad oil fraction and a heavy residue used for the production of bitumen.
The distillation of Priobskaya oil is carried out at atmospheric tubular units according to the scheme with single evaporation, i.e. with one complex distillation column with side stripping sections - this is the most energetically advantageous, because Priobskaya oil fully meets the requirements when using such an installation: a relatively low gasoline content (12-15%) and the yield of fractions up to 350 0 С is not more than 45%.
Crude oil, heated by hot flows in heat exchanger 2, is sent to electric dehydrator 3. From there, desalted oil is pumped through heat exchanger 4 to furnace 5 and then to distillation column 6, where it is evaporated once and separated into the required fractions. In the case of desalted oil, there is no electric dehydrator in the schemes of installations.
With a high content of dissolved gas and low-boiling fractions in oil, its processing according to such a scheme of single evaporation without preliminary evaporation is difficult, since increased pressure is created in the feed pump and in all devices located in the circuit upstream of the furnace. In addition, this increases the load of the furnace and distillation column.
The main purpose of vacuum distillation of fuel oil is to obtain a wide fraction (350 - 550 0С and above) - raw materials for catalytic processes and distillates for the production of oils and paraffins.
Fuel oil is pumped by a pump through a system of heat exchangers into a tube furnace, where it is heated to 350°-375°, and enters a distillation vacuum column. The vacuum in the column is created by steam jet ejectors (residual pressure 40-50 mm). Water vapor is fed into the bottom of the column. Oil distillates are taken from different plates of the column, pass through heat exchangers and coolers. From the bottom of the column, the remainder is discharged - tar.
Oil fractions isolated from oil are purified with selective solutions - phenol or furfural to remove some of the resinous substances, then dewaxed using a mixture of methyl ethyl ketone or acetone with toluene to lower the pour point of the oil. The processing of oil fractions is completed by post-treatment with bleaching clays. Recent oil technologies use hydrotreating processes instead of clays.
Material balance of atmospheric distillation of the Ob oil:
§4.Catalytic cracking
Catalytic cracking is the most important oil refining process, which significantly affects the efficiency of the refinery as a whole. The essence of the process lies in the decomposition of hydrocarbons that are part of the feedstock (vacuum gas oil) under the influence of temperature in the presence of a zeolite-containing aluminosilicate catalyst. The target product of the KK unit is a high-octane component of gasoline with an octane number of 90 points or more, its yield is from 50 to 65%, depending on the raw materials used, the technology and regime used. The high octane number is due to the fact that catalytic cracking also causes isomerization. The process produces gases containing propylene and butylenes, which are used as raw materials for petrochemicals and the production of high-octane gasoline components, light gas oil - a component of diesel and heating fuels, and heavy gas oil - a raw material for the production of soot, or a component of fuel oils.
The average capacity of modern plants is from 1.5 to 2.5 million tons, however, there are plants with a capacity of 4.0 million tons at the plants of the world's leading companies.
The key section of the plant is the reactor-regenerator block. The unit includes a raw material heating furnace, a reactor in which cracking reactions take place directly, and a catalyst regenerator. The purpose of the regenerator is to burn out the coke formed during cracking and deposited on the catalyst surface. The reactor, regenerator and feedstock input unit are connected by pipelines through which the catalyst circulates.
The catalytic cracking capacity at Russian refineries is currently clearly insufficient, and it is through the commissioning of new units that the problem with the predicted shortage of gasoline is being solved.
§4. Catalytic reforming
The development of gasoline production is associated with the desire to improve the main operational property of the fuel - the detonation resistance of gasoline, estimated by the octane number.
Reforming serves to simultaneously obtain a high-octane base stock motor gasoline, aromatic hydrocarbons and hydrogen-containing gas.
For the Priobskoy oil, the reforming is carried out on the fraction that boils away in the range of 85-180 0 C; an increase in the end of the boiling point promotes coke formation and is therefore undesirable.
Preparation of reforming feedstock - rectification to separate fractions, hydrotreating to remove impurities (nitrogen, sulfur, etc.) that poison the process catalysts.
The reforming process uses platinum catalysts. The high cost of platinum predetermined its low content in industrial catalysts reforming and hence the need for its effective use. This is facilitated by the use of alumina as a support, which has long been known as the best support for aromatization catalysts.
It was important to turn the alumina-platinum catalyst into a bifunctional reforming catalyst, on which the whole complex of reactions would proceed. To do this, it was necessary to impart the necessary acidic properties to the support, which was achieved by treating alumina with chlorine.
The advantage of a chlorinated catalyst is the ability to control the chlorine content in the catalysts, and hence their acidity, directly under operating conditions.
With the transition of existing reformers to polymetallic catalysts, performance indicators increased, because. their cost is lower, their high stability allows the process to be carried out at a lower pressure without fear of coking. When reforming on polymetallic catalysts, the content of the following elements in the feedstock should not exceed 1 mg/kg of sulfur, 1.5 mg/kg of nickel, and 3 mg/kg of water. In terms of nickel, Priobskaya oil is not suitable for polymetallic catalysts; therefore, aluminum-platinum catalysts are used in reforming.
Typical material balance of the reforming fraction is 85-180 °C at a pressure of 3 MPa.
Bibliographic list
1. Glagoleva O.F., Kapustin V.M. Primary oil refining (ch1), KolosS, M.: 2007
2. Abdulmazitov R.D., Geology and development of the largest oil and oil and gas fields in Russia, JSC VNIIOENG, M.: 1996
3. http://ru.wikipedia.org/wiki/Priobskoye_oil_field - about Priobye in Wikipedia
4. http://minenergo.gov.ru - Ministry of Energy of the Russian Federation
5. Bannov P.G., Processes of oil refining, TsNIITEneftekhim, M.: 2001
6. Boyko E.V., Chemistry of oil and fuels, UlGTU: 2007
7. http://vestnik.rosneft.ru/47/article4.html - Rosneft, company bulletin
They are in Saudi Arabia, even a high school student knows. As well as the fact that Russia is right behind it in the list of countries with significant oil reserves. However, in terms of production, we are inferior to several countries at once.
There are the largest in Russia in almost all regions: in the Caucasus, in the Ural and West Siberian districts, in the North, in Tatarstan. However, far from all of them have been developed, and some, such as Tekhneftinvest, whose sites are located in the Yamalo-Nenets and neighboring Khanty-Mansiysk districts, are unprofitable.
That is why on April 4, 2013 a deal was opened with the Rockefeller Oil Company, which has already started in the area.
However, not all oil and gas fields in Russia are unprofitable. Proof of this is the successful mining that several companies are conducting at once in the Yamalo-Nenets District, on both banks of the Ob.
The Priobskoye field is considered one of the largest not only in Russia, but also in the whole world. It was opened in 1982. It turned out that the reserves of West Siberian oil are located both on the left and on the right bank. Development on the left bank began six years later, in 1988, and on the right bank, eleven years later.
Today it is known that the Priobskoye field is more than 5 billion tons of high-quality oil, which is located at a depth not exceeding 2.5 kilometers.
Huge oil reserves made it possible to build the Priobskaya gas turbine power plant near the field, operating exclusively on associated fuel. This station not only fully meets the requirements of the field. It is able to supply the produced electricity to the Khanty-Mansiysk Okrug for the needs of residents.
Today, several companies are developing the Priobskoye field at once.
Some are sure that during extraction, finished, refined oil comes out of the ground. This is a deep delusion. Reservoir fluid that exits
The surface (raw oil) is delivered to the workshops, where it will be cleaned of impurities and water, the amount of magnesium ions will be normalized, and associated gas will be separated. This is a large and high-precision work. For its implementation, the Priobskoye field was provided with a whole complex of laboratories, workshops and transport networks.
Finished products (oil and gas) are transported and used for their intended purpose, leaving only waste. It is they who create today the biggest problem for the field: there are so many of them that it is still impossible to eliminate them.
The enterprise, created specifically for recycling, today processes only the “freshest” waste. Expanded clay is made from sludge (as the company calls it), which is in great demand in construction. However, so far only access roads for the deposit are being built from the resulting expanded clay.
The field has another significance: it provides stable, well-paid jobs for several thousand workers, among whom there are both highly qualified specialists and unskilled workers.
The Priobskoye field is located in the central part of the West Siberian Plain. Administratively, it is located in the Khanty-Mansiysk region, 65 km east of the city of Khanty-Mansiysk and 100 km west of the city of Khanty-Mansiysk. Nefteyugansk.
In the period 1978-1979. as a result of detailed seismic surveys of CDP MOV, the Priobskoe uplift was identified. From this moment, a detailed study of the geological structure of the territory begins: the widespread development of seismic surveys in combination with deep drilling.
The discovery of the Priobskoye field took place in 1982 as a result of drilling and testing of well 151, when a commercial inflow was obtained oil with a flow rate of 14.2 m 3 /day on a 4 mm choke from the intervals of 2885-2977 m (Tyumen suite YUS 2) and 2463-2467 m (formation AS 11 1) - 5.9 m 3 /day at a dynamic level of 1023 m.
The Ob structure, according to the tectonic map of the Meso-Cenozoic platform cover.
The West Siberian geosyneclise is located in the junction zone of the Khanty-Mansiysk depression, the Lyaminsky megatrough, the Salym and West Lyaminsky uplift groups.
The structures of the first order are complicated by swell-like and dome-shaped uplifts of the second order and separate local anticlinal structures, which are the objects of prospecting and exploration work on oil and gas.
Productive formations in the Priobskoye field are formations of the "AS" group: AS 7, AS 9, AS 10, AS 11, AS 12. In stratigraphic terms, these layers belong to the Cretaceous deposits of the Upper Vartovskaya suite. Lithologically, the Upper Vartovskaya Formation is composed of frequent and uneven intercalation of mudstones with sandstones and siltstones. Mudstones are dark gray, gray with a greenish tint, silty, micaceous. Sandstones and siltstones are gray, clayey, micaceous, fine-grained. Among mudstones and sandstones there are interlayers of argillaceous limestones and siderite concretions.
The rocks contain charred plant detritus, rarely bivalves (inocerams) of poor and moderate preservation.
Permeable rocks of productive formations have a northeastern and submeridial strike. Almost all reservoirs are characterized by an increase in the total effective thicknesses, the net-to-gross ratio, mainly towards the central parts of the reservoir development zones, to increase the reservoir properties and, accordingly, the clastic material is strengthened in the eastern (for layers of the AC 12 horizon) and north-eastern directions (for horizon AC 11).
Horizon AS 12 is a thick sand body elongated from southwest to northeast in the form of a wide band with maximum effective thicknesses up to 42 m in the central part (well 237). Three objects are distinguished in this horizon: the layers AC 12 3 , AC 12 1-2 , AC 12 0 .
The deposits of the AC 12 3 formation are presented as a chain of sandy lenticular bodies with a northeast strike. Effective thicknesses vary from 0.4 m to 12.8 m, with higher values associated with the main deposit.
The main deposit AS 12 3 was discovered at depths of -2620 and -2755 m and is lithologically shielded from all sides. The dimensions of the deposit are 34 x 7.5 km, and the height is 126 m.
Deposit AS 12 3 in the area of the well. 241 was discovered at depths of -2640-2707 m and is confined to the Khanty-Mansiysk local uplift. The reservoir is controlled from all sides by reservoir replacement zones. The size of the deposit is 18 x 8.5 km, height - 76 m.
Deposit AS 12 3 in the area of the well. 234 was uncovered at depths of 2632-2672 m and represents a sandstone lens at the western subsidence of the Priobskaya structure. The size of the deposit is 8.5 x 4 km, and the height is 40 m, the type is lithologically screened.
Deposit AS 12 3 in the area of the well. 15-C was discovered at depths of 2664-2689 m within the Selyarovsky structural ledge. The dimensions of the lithologically screened deposit are 11.5 x 5.5 km, and the height is 28 m.
The AS 12 1-2 deposit is the main one, it is the largest in the field. It is confined to a monocline complicated by local uplifts of small amplitude (boreholes 246, 400) with transition zones between them. On three sides it is limited by lithological screens, and only in the south (towards the Vostochno-Frolovskaya area) do reservoirs tend to develop. However, given the considerable distances, the boundary of the deposit is still conditionally limited to a line passing 2 km south of the well. 271 and 259. Oil-saturated thickness varies in a wide range from 0.8 m (well 407) to 40.6 m (well 237) tributaries oil up to 26 m 3 /day on a 6 mm choke (well 235). The size of the deposit is 45 x 25 km, height - 176 m.
Deposit AS 12 1-2 in the area of the well. 4-KhM was discovered at depths of 2659-2728 m and is associated with a sandy lens on the northwestern slope of the Khanty-Mansiysk local uplift. Oil-saturated thickness varies from 0.4 to 1.2 m. The size of the deposit is 7.5 x 7 km, height - 71 m.
Deposit AS 12 1-2 in the area of the well. 330 opened at depths of 2734-2753m Oil-saturated thickness varies from 2.2 to 2.8 m. The size of the deposit is 11 x 4.5 km, height - 9 m. Type - lithologically screened.
The deposits of the AC 12 0 formation - the main one - were discovered at depths of 2421-2533 m. It is a lenticular body oriented from the southwest to the northeast. Oil-saturated thicknesses vary from 0.6 (well 172) to 27 m (well 262). tributaries oil up to 48 m 3 / day on an 8 mm fitting. The dimensions of the lithologically screened deposit are 41 x 14 km, the height is 187 m. 331 was discovered at depths of 2691-2713 m and is a lens of sandy rocks. oil-saturated thickness in this well is 10 m. Dimensions 5 x 4.2 km, height - 21 m. Debit oil- 2.5 m 3 / day per Hd \u003d 1932 m.
The deposit of the AS 11 2-4 formation is of lithologically shielded type, there are 8 in total, discovered by 1-2 wells. In terms of area, the deposits are located in the form of 2 chains of lenses in the eastern part (the most elevated) and in the west in the more submerged part of the monoclinal structure. Oil-saturated thicknesses in the east increase by 2 or more times compared to western wells. The overall range of change is from 0.4 to 11 m.
The deposit of the AS 11 2-4 formation in the area of well 246 was discovered at a depth of 2513-2555 m. The dimensions of the deposit are 7 x 4.6 km, the height is 43 m.
The deposit of the AS 11 2-4 formation in the area of the well 247 was discovered at a depth of 2469-2490 m. The size of the deposit is 5 x 4.2 km, the height is 21 m.
The deposit of the AS 11 2-4 formation in the area of the well 251 was discovered at a depth of 2552-2613 m. The size of the deposit is 7 x 3.6 km, the height is 60 m.
The deposit of the AS 11 2-4 formation in the area of the well 232 was discovered at a depth of 2532-2673m. The size of the deposit is 11.5 x 5 km, the height is 140 m.
The deposit of the AS 11 2-4 formation in the area of the well 262 was discovered at a depth of 2491-2501m. The size of the deposit is 4.5 x 4 km, height - 10 m.
The deposit of the AS 11 2-4 formation in the area of well 271 was discovered at a depth of 2550-2667m. The size of the deposit is 14 x 5 km.
The deposit of the AS 11 2-4 formation in the area of the well 151 was discovered at a depth of 2464-2501m. The size of the deposit is 5.1 x 3 km, height - 37 m.
The deposit of the AS 11 2-4 formation in the area of the well 293 was discovered at a depth of 2612-2652 m. The size of the deposit is 6.2 x 3.6 km, the height is 40 m.
The deposits of the AC 11 1 formation are confined mainly to the crest part in the form of a wide strip of northeast strike, limited on three sides by clay zones.
The main deposit AS 11 1 is the second in value within the Priobskoye field, it was discovered at depths of 2421-2533 m. 259. Debits oil vary from 2.46 m 3 /day at a dynamic level of 1195 m (well 243) to 118 m 3 /day through an 8 mm choke (well 246). Oil-saturated thicknesses vary from 0.4 m (well 172) to 41.6 (well 246). The size of the deposit is 48 x 15 km, the height is up to 112 m, the type is lithologically screened.
Deposits of the AC 11 0 formation. The AS 11 0 formation has a very small zone of reservoir development in the form of lenticular bodies confined to the submerged sections of the crest.
Deposit AS 11 0 in the area of the well. 408 was discovered at a depth of 2432-2501 m. The size of the deposit is 10.8 x 5.5 km, the height is 59 m, the type is lithologically screened. Debit oil from well 252 amounted to 14.2 m3/day for Hd = 1410 m.
Deposit AS 11 0 in the area of the well. 172 was opened by one well at a depth of 2442-2446 m and has dimensions of 4.7 x 4.1 km, height - 3 m. Debit oil amounted to 4.8 m 3 / day for Hd \u003d 1150 m.
Deposit AS 11 0 in the area of the well. 461 measures 16 x 6 km. oil-saturated thickness varies from 1.6 to 4.8 m. Deposit type - lithologically shielded. Debit oil from well 461 amounted to 15.5 m 3 / day, Nd = 1145 m.
Deposit AS 11 0 in the area of the well. 425 opened by one well. oil-saturated power - 3.6 m. Debit oil amounted to 6.1 m 3 / day per Hd \u003d 1260 m.
The AC 10 horizon was exposed within the central zone of the Priobskoye field, where it is confined to more submerged places near the crest, as well as to the southwestern flank of the structure. The division of the horizon into layers AS 10 1, AS 10 2-3 (in the central and eastern parts) and AS 10 2-3 (in the western part) is to a certain extent conditional and is determined by the conditions of occurrence, formation of these deposits, taking into account the lithological composition of the rocks and the physical chemical characterization oils.
The main deposit AS 10 2-3 was discovered at depths of 2427-2721 m and is located in the southern part of the deposit. Debits oil are in the range from 1.5 m 3 /day on an 8 mm choke (well 181) to 10 m 3 /day on Hd = 1633 m (well 421). Oil-saturated thicknesses range from 0.8 m (well 180) to 15.6 m (well 181). The size of the deposit is 31 x 11 km, the height is up to 292 m, the deposit is lithologically shielded.
Deposit AS 10 2-3 in the area of the well. 243 was discovered at depths of 2393-2433 m. Debit oil is 8.4 m 3 /day at Hd = 1248 m (well 237). Oil-saturated thickness - 4.2 - 5 m. Dimensions 8 x 3.5 km, height up to 40 m. Deposit type - lithologically shielded.
Deposit AS 10 2-3 in the area of the well. 295 was opened at depths of 2500-2566 m and is controlled by clay formation zones. Oil-saturated thicknesses vary from 1.6 to 8.4 m. 295, 3.75 m 3 /day was obtained at Hd = 1100 m. The size of the deposit is 9.7 x 4 km, the height is 59 m.
The main deposit AS 10 1 was discovered at depths of 2374-2492 m. 259 and 271. Oil-saturated thicknesses vary from 0.4 (well 237) to 11.8 m (well 265). Debits oil: from 2.9 m 3 / day at Hd = 1064 m (well 236) to 6.4 m 3 / day on a 2 mm choke. The size of the deposit is 38 x 13 km, the height is up to 120 m, the deposit type is lithologically screened.
Deposit AS 10 1 in the area of the well. 420 was discovered at depths of 2480-2496 m. The size of the deposit is 4.5 x 4 km, the height is 16 m.
Deposit AS 10 1 in the area of the well. 330 was discovered at depths of 2499-2528 m. The size of the deposit is 6 x 4 km, the height is 29 m.
Deposit AS 10 1 in the area of the well. 255 was discovered at depths of 2468-2469 m. The size of the deposit is 4 x 3.2 km.
The section of the AS 10 formation is completed by the productive formation AS 10 0 . Within which three deposits were identified, located in the form of a chain of submeridian strike.
Deposit AC 10 0 in the area of the well. 242 was uncovered at depths of 2356-2427 m and is lithologically shielded. Debits oil are 4.9 - 9 m 3 / day at Hd-1261-1312 m. Oil-saturated the thickness is 2.8 - 4 m. The dimensions of the deposit are 15 x 4.5 km, the height is up to 58 m.
Deposit AC 10 0 in the area of the well. 239 was discovered at depths of 2370-2433 m. Flow rates oil are 2.2 - 6.5 m 3 / day at Hd-1244-1275 m. Oil-saturated the thickness is 1.6 -2.4 m. The size of the deposit is 9 x 5 km, the height is up to 63 m.
Deposit AC 10 0 in the area of the well. 180 was exposed at depths of 2388-2391 m and is lithologically shielded. oil-saturated thickness - 2.6m. tributary oil amounted to 25.9 m 3 / day at Hd-1070 m.
The cap above the AC 10 horizon is represented by a pack of clayey rocks varying from 10 to 60 m from east to west.
Sandy-silty rocks of the AS 9 formation have a limited distribution and are presented in the form of facies windows, tending mainly to the northeastern and eastern parts of the structure, as well as to the southwestern subsidence.
The deposit of the AS 9 formation in the area of the well. 290 was discovered at depths of 2473-2548 m and is confined to the western part of the deposit. Oil-saturated thicknesses range from 3.2 to 7.2 m. oil are 1.2 - 4.75 m 3 / day with Hd - 1382-1184 m. The size of the deposit is 16.1 x 6 km, the height is up to 88 m.
Two small deposits (6 x 3 km) were discovered in the east of the deposit. Oil-saturated thickness varies from 0.4 to 6.8 m. Tributaries oil 6 and 5.6 m 3 /day at Hd =1300-1258 m. The deposits are lithologically shielded.
The Neocomian productive deposits are completed by the AC 7 layer, which has a very mosaic pattern in placement. oil-bearing and aquifers.
The largest in area eastern deposit of formation AS 7 was discovered at depths of 2291-2382 m. It is contoured on three sides by reservoir replacement zones, and in the south its boundary is conditional and drawn along a line passing 2 km from wells 271 and 259. The deposit is oriented from the south -west to northeast. tributaries oil: 4.9 - 6.7 m 3 / day per Hd \u003d 1359-875 m. Oil-saturated thickness varies from 0.8 to 7.8 m. The dimensions of the lithologically screened deposit are 46 x 8.5 km, height up to 91 m.
Deposit AS 7 in the area of the well. 290 was discovered at a depth of 2302-2328 m. Oil-bearing thicknesses are 1.6 - 3 m. In the well. 290 received 5.3 m 3 / day oil at P = 15MPA. The size of the deposit is 10 x 3.6 km, the height is 24 m.
Deposit AS 7 in the area of the well. 331 was uncovered at a depth of 2316-2345 m and is a lenticular body of an arcuate shape. Oil-saturated thicknesses vary from 3 to 6 m. 331 inflow received oil 1.5 m 3 /day at Hd = 1511 m. The dimensions of the lithologically screened deposit are 17 x 6.5 km, height - 27 m.
Deposit AS 7 in the area of the well. 243 was discovered at a depth of 2254-2304 m. Oil-saturated thickness 2.2-3.6 m. Dimensions 11.5 x 2.8 km, height - 51 m. In the well 243 received oil 1.84 m 3 / day on Nd-1362 m.
Deposit AS 7 in the area of the well. 259 was uncovered at a depth of 2300 m; it is a lens of sandstones. oil-saturated thickness 5.0 m. Dimensions 4 x 3 km.
Priobskoye field
|
Name indicators |
Category |
AC 12 3 |
AC 12 1-2 |
AC 12 0 |
AC 11 2-4 |
AC 11 1 |
AC 11 0 |
AC 10 2-3 |
AC 10 1 |
AC 10 0 |
AC 9 |
AC 7 |
|
Initial recoverable reserves, thousand tons |
Sun 1 From 2 |
7737 3502 |
230392 39058 |
26231 1908 |
3725 |
266919 4143 |
1377 |
40981 4484 |
33247 2643 |
1879 5672 |
||
|
Accumulated booty, thousand tons |
1006 |
|||||||||||
|
Annual booty, thousand tons |
||||||||||||
|
Well fund mining injection |
||||||||||||
|
Scheme drilling out |
3-row |
3-row |
3-row |
3-row |
3-row |
3-row |
3-row |
3-row |
3-row |
|||
|
Grid size |
500*500 |
500*500 |
500*500 |
500*500 |
500*500 |
500*500 |
500*500 |
500*500 |
500*500 |
|||
|
Density wells |
Brief geological and field characteristics of the reservoirs
Priobskoye field
|
Options |
Index |
reservoir |
|||||||||||||
|
Productive layer |
AC 12 3 |
AC 12 1-2 |
AC 12 0 |
AC 11 2-4 |
AC 11 1 |
AC 11 0 |
AC 10 2-3 |
AC 10 1 |
AC 10 0 |
AC 9 |
AC 7 |
||||
|
Seam roof depth, m |
2620-2802 |
2536-2753 |
2495-2713 |
2464-2667 |
2421-2533 |
2442-2501 |
2393-2721 |
2374-2528 |
2356-2433 |
2393-2548 |
2254-2382 |
||||
|
Absolute elevation of the seam top, m |
2587-2750 |
2504-2685 |
2460-2680 |
2423-2618 |
2388-2500 |
2400-2459 |
2360-2686 |
2340-2460 |
2322-2400 |
2357-2514 |
2220-2348 |
||||
|
Absolute mark of VNK, m |
|||||||||||||||
|
Total seam thickness, m |
18.8 |
||||||||||||||
|
Effective thickness, m |
11.3 |
10.6 |
|||||||||||||
|
oil-saturated thickness, m |
2.88 |
4.68 |
1.69 |
1.52 |
4.72 |
3.25 |
1.72 |
2.41 |
2.47 |
||||||
|
Net-to-gross ratio, shares, units |
0.49 |
0.40 |
0.45 |
0.28 |
0.53 |
0.63 |
0.47 |
0.48 |
0.51 |
0.42 |
0.54 |
||||
Petrophysical characterization of reservoirs
|
Options |
Index |
reservoir |
|||||||||||||
|
Productive layer |
AC 12 3 |
AC 12 1-2 |
AC 12 0 |
AC 11 2-4 |
AC 11 1 |
AC 11 0 |
AC 10 2-3 |
AC 10 1 |
AC 10 0 |
AC 9 |
AC 7 |
||||
|
Carbonate,% |
min-mac average |
3.05 3.05 |
1.9-5.1 |
2.2-5.6 |
1.6-4.6 |
1.3-2.1 |
|||||||||
|
With grain size, 0.5-0.25mm |
min-mac average |
1.75 |
|||||||||||||
|
with a grain size of 0.25-0.1 mm |
min-mac average |
35.45 |
35.9 |
38.5 |
42.4 |
41.4 |
28.7 |
||||||||
|
with a grain size of 0.1-0.01 mm |
min-mac average |
53.2 |
51.3 |
48.3 |
46.3 |
42.3 |
60.7 |
||||||||
|
with a grain size of 0.01 mm |
min-mac average |
11.0 |
10.3 |
15.3 |
|||||||||||
|
sorting factor, |
min-mac average |
1.814 |
1.755 |
1.660 |
1.692 |
||||||||||
|
Median grain size, mm |
min-mac average |
0.086 |
0.089 |
0.095 |
0.073 |
||||||||||
|
Clay content,% |
|||||||||||||||
|
type of cement |
clayey, carbonate-clayey, film-porous. |
||||||||||||||
|
Coeff. Open porosity. by core, fractions of a unit |
Ming-mak average |
0.17 0.16-0.18 |
0.18 0.17-0.19 |
0.18 0.17-0.20 |
0.19 0.18-0.19 |
0.20 0.18-0.22 |
0.18 0.18 |
0.20 0.20-0.22 |
0.17 0.17 |
||||||
|
Coeff. core permeability, 10 -3 µm 2 |
min-mac average |
1.04 1.0-1.05 |
5.41 0.59-20.2 |
4.76 0.57-13.0 |
15.9 4.3-27.0 |
47.0 2.2-87.6 |
2.2 2.2-23.1 |
||||||||
|
Water holding capacity,% |
min-mac average |
||||||||||||||
|
Coeff. Open porosity according to logging, USD |
|||||||||||||||
|
Coeff. Well logging permeability, 10 -3 µm 2 |
|||||||||||||||
|
Coeff. Oil saturation according to GIS, shares of units |
0.41 |
0.44 |
0.45 |
0.71 |
0.62 |
0.73 |
|||||||||
|
Initial reservoir pressure, MPa |
25.73 |
25.0 |
25.0 |
25.54 |
26.3 |
||||||||||
|
Reservoir temperature, С |
|||||||||||||||
|
Debit oil according to the results of the reconnaissance test. well m3/day |
Ming-mak average |
1.0-7.5 |
0.1-26.0 |
2.5-21.6 |
0.4-25.5 |
2.5-118 |
5.94-14.2 |
1.5-58 |
1.64-6.4 |
9-25.9 |
1.2-4.8 |
1.5-6.7 |
|||
|
Productivity, m3/day MPa |
min-mac average |
2.67 |
2.12 |
4.42 |
1.39 |
||||||||||
|
Hydraulic conductivity, 10 -11 m -3 / Pa * sec. |
min-mac average |
58.9 |
55.8 |
55.1 |
28.9 |
38.0 |
34.6 |
||||||||
Physico-chemical characteristics oil and gas
|
Options |
Index |
reservoir |
|
|
Productive layer |
AC 12 3 |
AC 11 2-4 |
AC 10 1 |
|
Density oil in the surface conditions,kg/m3 |
886.0 |
884.0 |
|
|
Density oil in reservoir conditions |
|||
|
Viscosity in surface conditions, mPa.s |
32.26 |
32.8 |
29.10 |
|
Viscosity in reservoir conditions |
1.57 |
1.41 |
1.75 |
|
Silica gel resins |
7.35 |
7.31 |
|
|
asphaltenes |
2.70 |
2.44 |
2.48 |
|
Sulfur |
1.19 |
1.26 |
1.30 |
|
Paraffin |
2.54 |
2.51 |
2.73 |
|
pour point oil, С 0 |
|||
|
Temperature saturation oil paraffin, С 0 |
|||
|
Fraction yield,% |
|||
|
up to 100 С 0 |
|||
|
up to 150 С 0 |
66.8 |
||
|
up to 200 С 0 |
15.1 |
17.0 |
17.5 |
|
up to 250 С 0 |
24.7 |
25.9 |
26.6 |
|
up to 300 С 0 |
38.2 |
39.2 |
|
|
Component composition oil(molar Concentration,%) |
|||
|
Carbonic gas |
0.49 |
0.52 |
0.41 |
|
Nitrogen |
0.25 |
0.32 |
0.22 |
|
Methane |
22.97 |
23.67 |
18.27 |
|
Ethane |
4.07 |
4.21 |
5.18 |
|
Propane |
6.16 |
6.83 |
7.58 |
|
Isobutane |
1.10 |
1.08 |
1.13 |
|
normal butane |
3.65 |
3.86 |
4.37 |
|
Isopentane |
1.19 |
1.58 |
1.25 |
|
normal pentane |
2.18 |
2.15 |
2.29 |
|
С6+higher |
57.94 |
55.78 |
59.30 |
|
Molecular weight, kg/mol |
161.3 |
||
|
Saturation pressure, mPa |
6.01 |
||
|
Volume ratio |
1.198 |
1.238 |
1.209 |
|
Gas factor under conditional separation m 3 / t |
|||
|
Density gas,kg/m3 |
1.242 |
1.279 |
1.275 |
|
Type of gas |
|||
|
Component composition petroleum gas (molar concentration,%) |
|||
|
Nitrogen |
1.43 |
1.45 |
1.26 |
|
Carbonic gas |
0.74 |
0.90 |
0.69 |
|
Methane |
68.46 |
66.79 |
57.79 |
|
Ethane |
11.17 |
1.06 |
15.24 |
|
Propane |
11.90 |
13.01 |
16.42 |
|
Isobutane |
1.26 |
1.26 |
1.54 |
|
normal butane |
3.24 |
3.50 |
4.72 |
|
Isopentane |
0.49 |
0.67 |
0.65 |
|
Pentane |
0.71 |
0.73 |
0.95 |
|
С6+higher |
0.60 |
0.63 |
0.74 |
Composition and properties of formation waters
|
aquifer complex |
|||
|
Productive layer |
AC 12 0 |
AC 11 0 |
AC 10 1 |
|
Density of water in surface conditions, t/m3 |
|||
|
Mineralization, g/l |
|||
|
Water type |
chlorine-ka- |
oblique |
|
|
Chlorine |
9217 |
||
|
Sodium+Potassium |
5667 |
||
|
Calliy |
|||
|
Magnesium |
|||
|
Bicarbonate |
11.38 |
||
|
iodine |
47.67 |
||
|
Bromine |
|||
|
Bor |
|||
|
Amonius |
40.0 |
||
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Introduction
1 Geological characteristics of the Priobskoye field
1.1 General information about the deposit
1.2 Lithostratigraphic section
1.3 Tectonic structure
1.4 Oil content
1.5 Reservoir characterization
1.6 Characteristics of aquifers
1.7 Physiochemical properties formation fluids
1.8 Estimation of oil reserves
1.8.1 Oil reserves
2. Main technical and economic indicators of the development of the Priobskoye field
2.1 Dynamics of the main indicators of the development of the Priobskoye field
2.2 Analysis of the main technical and economic development indicators
2.3 Development features affecting well operation
3. Applied methods of enhanced oil recovery
3.1 Choice of the method of impact on the oil reservoir
3.2 Geological and physical criteria for the applicability of various methods of impact on the Priobskoye field
3.2.1 Water flooding
3.3 Methods of influencing the bottomhole zone of a well to stimulate oil production
3.3.1 Acid treatments
3.3.2 Hydraulic fracturing
3.3.3 Improving perforation efficiency
Conclusion
Introduction
The oil industry is one of the most important components of the Russian economy, directly affecting the formation of the country's budget and its exports.
The state of the resource base of the oil and gas complex is the most acute problem today. Oil resources are gradually depleted, a large number of fields are in the final stage of development and have a large percentage of water cut, therefore, the most urgent and paramount task is to search for and put into operation young and promising deposits, one of which is the Priobskoye field (in terms of reserves, it is one of the largest fields in Russia).
The balance reserves of oil approved by the State Reserves Commission for category C 1 amount to 1827.8 million tons, recoverable 565.0 million tons. with an oil recovery factor of 0.309, taking into account reserves in the buffer zone under the floodplains of the Ob and Bolshoi Salym rivers.
The balance reserves of category C 2 oil are 524,073 thousand tons, recoverable - 48,970 thousand tons, with an oil recovery factor of 0.093.
The Priobskoye field has a number of characteristic features:
large, multilayer, unique in terms of oil reserves;
inaccessible, characterized by significant swampiness, in the spring and summer most of the territory is flooded with flood waters;
The Ob River flows through the field, dividing it into right-bank and left-bank parts.
The field is characterized by a complex structure of productive horizons. The formations AC10, AC11, AC12 are of industrial interest. The reservoirs of horizons AC10 and AC11 are medium and low productive, and AC12 are anomalously low productive. The exploitation of the AC12 formation should be singled out as a separate development problem, since , the AC12 reservoir is also the most significant of all reservoirs in terms of reserves. This characteristic indicates the impossibility of developing the field without actively influencing its productive strata.
One of the ways to solve this problem is the implementation of measures to intensify oil production.
1 . Geological characteristicPriobskyPlace of Birth
1.1 General information about the deposit
The Priobskoye oil field is administratively located in the Khanty-Mansiysk region of the Khanty-Mansiysk Autonomous Okrug of the Tyumen region.
The area of work is located 65 km east of the city of Khanty-Mansiysk, 100 km west of the city of Nefteyugansk. At present, the area is one of the most economically developing in the Autonomous Okrug, which became possible due to the growth in the volume of geological exploration and oil production .
The largest nearby fields being developed are: Salymskoye, located 20 km to the east, Prirazlomnoye, located in the immediate vicinity, Pravdinskoye, 57 km to the southeast.
The Urengoy - Chelyabinsk - Novopolotsk gas pipeline and the Ust-Balyk-Omsk oil pipeline pass to the south-east of the field.
The northern part of the Priobskaya area is located within the Ob floodplain - a young alluvial plain with the accumulation of relatively large Quaternary deposits. The absolute relief marks are 30-55 m. The southern part of the area gravitates towards a flat alluvial plain at the level of the second floodplain terrace with weakly expressed forms of river erosion and accumulation. The absolute marks here are 46-60 m.
The hydrographic network is represented by the Maly Salym channel, which flows in a sublatitudinal direction in the northern part of the area and in this area is connected by the small channels Malaya Berezovskaya and Pola with the large and full-flowing Ob channel Bolshoi Salym. The Ob River is the main waterway of the Tyumen region. Within the region there is a large number of lakes, the largest of which are Olevashkina lake, Karasye lake, Okunevoye lake. The swamps are impassable, freeze by the end of January and are the main obstacle to the movement of vehicles.
The climate of the region is sharply continental with long winters and short warm summers. Winter is frosty and snowy. The coldest month of the year is January (average monthly temperature is -19.5 degrees C). The absolute minimum is -52 degrees C. The warmest is July (the average monthly temperature is +17 degrees C), the absolute maximum is +33 degrees C. The average annual precipitation is 500-550 mm per year, with 75% falling on the warm season. Snow cover is established in the second half of October and continues until early June. The thickness of the snow cover is from 0.7 m to 1.5-2 m. The depth of soil freezing is 1-1.5 m.
The area under consideration is characterized by podzolic clay soils in relatively elevated areas and peaty-podzolic-silt and peat soils in wetlands. Within the plains, the alluvial soils of the river terraces are mostly sandy, sometimes clayey. Vegetable world varied. Coniferous and mixed forest prevails.
The area is located in a zone of disjunct occurrence of near-surface and relict permafrost rocks. Near-surface frozen soils lie on watersheds under peat bogs. Their thickness is controlled by the groundwater level and reaches 10-15 m, the temperature is constant and close to 0 degrees C.
In adjacent territories (frozen rocks have not been studied at the Priobskoye field), permafrost occurs at depths of 140-180 m (Lyantorskoye field). The permafrost thickness is 15-40 m, rarely more. Frozen are more often the lower, more clayey, part of the Novomikhailovskaya and an insignificant part of the Atlymskaya suites.
The largest settlements closest to the work area are the cities of Khanty-Mansiysk, Nefteyugansk, Surgut and from smaller settlements - the villages of Seliyarovo, Sytomino, Lempino and others.
1.2 Lithostratigraphicincision
The geological section of the Priobskoye deposit is composed of a thick layer (more than 3000 m) of terrigenous deposits of the sedimentary cover of the Meso-Cenozoic age, overlying the rocks of the pre-Jurassic complex, represented by the weathering crust.
Pre-Jurassic education (Pz)
In the section of the pre-Jurassic sequence, two structural stages are distinguished. The lower one, confined to the consolidated crust, is represented by strongly dislocated graphite-porphyrites, gravelstones, and metamorphosed limestones. The upper stage, identified as an intermediate complex, consists of less dislocated effusive-sedimentary deposits of the Permian-Triassic age up to 650 m thick.
Jurassic system (J)
The Jurassic system is represented by all three divisions: lower, middle and upper.
It includes the Tyumen (J1+2), Abalak and Bazhenov formations (J3).
deposits Tyumen the suites lie at the base of the sedimentary cover on the rocks of the weathering crust with angular and stratigraphic unconformity and are represented by a complex of terrigenous rocks of clayey-sandy-siltstone composition.
The thickness of the deposits of the Tyumen suite varies from 40 to 450 m. Within the deposit, they are discovered at depths of 2806-2973m. The deposits of the Tyumen Formation are conformably overlapped by the Upper Jurassic deposits of the Abalak and Bazhenov Formations. Abalakskaya the suite is composed of dark gray to black, locally calcareous, glauconite mudstones with siltstone intercalations in the upper part of the section. The thickness of the suite ranges from 17 to 32 m.
deposits Bazhenov the formations are represented by dark gray, almost black, bituminous argillites with intercalations of weakly silty argillites and organic-argillaceous-carbonate rocks. The thickness of the suite is 26-38 m.
Chalk system (K)
The deposits of the Cretaceous system are developed everywhere and are represented by the upper and lower sections.
The Akh, Cherkashin, Alym, Vikulov, and Khanty-Mansi suites are distinguished from bottom to top, and the Khanty-Mansi, Uvat, Kuznetsov, Berezov, and Gankin suites are distinguished in the upper section.
Bottom part akhskoy Formation (K1g) is represented mainly by mudstones with subordinate thin interlayers of siltstones and sandstones, united in the Achimov sequence.
In the upper part of the Akh Formation, a aged member of finely elutriated, dark gray, approaching gray Pim clays stands out.
The total thickness of the formation varies from west to east from 35 to 415 m. In the sections located to the east, a group of layers BS1-BS12 is confined to this stratum.
Incision Cherkashin suite (K1g-br) is represented by a rhythmic alternation of gray clays, siltstones and silty sandstones. The latter, within the field, as well as sandstones, are commercially oil-bearing and stand out in the layers AC7, AC9, AC10, AC11, AC12.
The thickness of the suite varies from 290 to 600 m.
Above are dark gray to black clays. alym suites (K1a), in the upper part with interlayers of bituminous mudstones, in the lower part - siltstones and sandstones. The thickness of the suite varies from 190 to 240 m. Clays are a regional cover for hydrocarbon deposits throughout the Sredneobskaya oil and gas region.
Vikulovskaya suite (K1a-al) consists of two subformations.
The lower one is predominantly clayey, the upper one is sandy-clayey with a predominance of sandstones and siltstones. The formation is characterized by the presence of plant detritus. The thickness of the suite ranges from 264 m in the west to 296 m in the northeast.
Khanty-Mansiysk the suite (K1a-2s) is represented by uneven interbedding of sandy-argillaceous rocks with a predominance of the former in the upper part of the section. The rocks of the suite are characterized by an abundance of carbonaceous detritus. The thickness of the suite varies from 292 to 306 m.
Uvatskaya the suite (K2s) is represented by uneven overcasting of sands, siltstones, and sandstones. The formation is characterized by the presence of charred and ferruginous plant remains, carbonaceous detritus, and amber. The thickness of the formation is 283-301 m.
Bertsovskaya the formation (K2k-st-km) is subdivided into two subformations. The lower one, consisting of clays, gray montmorellonite, with opoka-like interlayers, from 45 to 94 m thick, and the upper one, represented by gray, dark gray, siliceous, sandy clays, 87-133 m thick.
Gankinskaya the suite (K2mP1d) consists of gray, greenish-gray clays turning into marls with glauconite grains and siderite concretions. Its thickness is 55-82m.
Paleogene system (P2)
The Paleogene system includes the rocks of the Talitsky, Lyulinvorsky, Atlymsky, Novomikhailovsky and Turtas formations. The first three are marine deposits, the rest are continental.
Talitskaya the formation is composed of a layer of dark gray clays, silty in some areas. There are peritized plant remains and fish scales. The thickness of the formation is 125-146 m.
Lyulinvorskaya the suite is represented by yellowish-green clays, in the lower part of the section, often opocoid with interlayers of flasks. The thickness of the formation is 200-363 m.
Tavdinskaya the suite that completes the section of the Marine Paleogene is made up of gray, bluish-gray clays with siltstone interbeds. The thickness of the suite is 160-180 m.
Atlymskaya the formation is composed of continental alluvial-marine deposits, consisting of sands, gray to white, predominantly quartz with interlayers of brown coal, clays and siltstones. The thickness of the suite is 50-60 m.
Novomikhaylovskaya suite - represented by uneven interbedding of gray, fine-grained, quartz-feldspar sands with gray and brownish-gray clays and siltstones with interlayers of sands and brown coals. The thickness of the formation does not exceed 80 m.
Turtasskaya the suite consists of greenish-gray clays and siltstones, thinly bedded with interlayers of diatomites and quartz-glauconite sands. The thickness of the suite is 40-70 m.
Quaternary system (Q)
It is present everywhere and is represented in the lower part by the alternation of sands, clays, loams and sandy loams, in the upper part - by marsh and lake facies - silts, loams and sandy loams. The total thickness is 70-100 m.
1.3 Tectonicstructure
The Ob structure is located in the junction zone of the Khanty-Mansi depression, the Lyaminsky megatrough, and the Salym and West Lempa uplift groups. The structures of the first order are complicated by swell-like and dome-shaped uplifts of the second order and separate local anticlinal structures, which are the objects of prospecting and exploration for oil and gas.
The modern structural plan of the pre-Jurassic basement was studied from the reflecting horizon "A". On the structural map, along the reflecting horizon "A", all structural elements are displayed. In the southwestern part of the region - Seliyarovskoe, West Sakhalinskoe, Svetloye uplifts. In the northwestern part - East Selyarovskoye, Krestovoe, Zapadno-Gorshkovskoye, Yuzhno-Gorshkovskoye, complicating the eastern slope of the West Lempinskaya uplift zone. In the central part - the West Sakhalin trough, to the east of it the Gorshkov and Sakhalin uplifts, complicating the Sredne-Lyamin swell and the Sakhalin structural nose, respectively.
On the reflecting horizon "Db", confined to the top of the Bystrinskaya member, the Priobskoe dome-shaped uplift, the West Priobskoe low-amplitude uplift, the West Sakhalinskaya, Novoobskaya structures are traced. In the west of the area, the Khanty-Mani uplift is outlined. To the north of the Priobsky uplift, the Light local uplift stands out. In the southern part of the field in the area of the well. 291 The nameless uplift is conditionally distinguished. The East Seliyarovskaya uplifted zone in the study area is delineated by an open seismic isohypse - 2280 m. Near well 606, a low-amplitude isometric structure can be traced. The Seliyarovskaya area is covered with a sparse network of seismic profiles, on the basis of which a positive structure can be conditionally predicted. Selyarovsky uplift is confirmed structural plan along the reflecting horizon "B". Due to the poor study of the western part of the area, seismic exploration, to the north of the Seliyarovskaya structure, a dome-shaped nameless uplift is conventionally distinguished.
1.4 Oil content
At the Priobskoye field, the oil-bearing stage covers deposits of a sedimentary cover of considerable thickness from the Middle Jurassic to Aptian age and is more than 2.5 km.
Non-industrial oil inflows and core with signs of hydrocarbons were obtained from the deposits of the Tyumen (formations Yu 1 and Yu 2) and Bazhenov (formation Yu 0) formations. Due to the limited number of available geological and geophysical materials, the structure of the deposits has not been sufficiently substantiated to date.
Commercial oil-bearing capacity has been established in the Neocomian formations of the AS group, where 90% of explored reserves are concentrated. The main productive strata are enclosed between the Pimskaya and Bystrinskaya clay units. The deposits are confined to lenticular sand bodies formed in the shelf and clinoform deposits of the Neocomian, the productivity of which is not controlled by the modern structural plan and is determined practically only by the presence of productive reservoir layers in the section. The absence of formation water in the productive part of the section during numerous tests proves that the oil deposits associated with the layers of these packs are closed lenticular bodies completely filled with oil, and the contours of the deposits for each sandy layer are determined by the boundaries of its distribution. The exception is the AC 7 reservoir, where formation water inflows were obtained from sand lenses filled with water.
As part of the productive Neocomian deposits, 9 estimated objects were identified: AS 12 3, AS 12 2, AS 11 2-4, AS 11 1, AS 11 0, AS 10 1-2, AS 10 0, AS 9, AS 7. Deposits of layers AC 7, AC 9 are not of industrial interest.
The geological profile is shown in Figure 1.1
1.5 Characterizationproductivelayers
The main oil reserves at the Priobskoye field are concentrated in Neocomian deposits. A feature of the geological structure of deposits associated with Neocomian rocks is that they have a mega-cross-layered structure, due to their formation under conditions of lateral filling of a fairly deep sea basin (300-400m) due to the removal of detrital terrigenous material from the east and southeast. The formation of the Neocomian mega-complex of sedimentary rocks occurred in a whole series of paleogeographic conditions: continental sedimentation, coastal-marine, shelf, and very slow sedimentation in the open deep sea.
As one moves from east to west, there is a slope (in relation to the Bazhenov formation, which is a regional benchmark) of both clayey seasoned packs (zonal benchmark) and sandy-siltstone rocks contained between them.
According to the determinations made by specialists from ZapSibNIGNI on fauna and spore pollen, selected from clays in the interval of occurrence of the Pimsk Member, the age of these deposits turned out to be Hauterivian. All layers that are above the Pimsk member. Indexed as a group of AS, therefore, at the Priobskoye field, the BS 1-5 formations were re-indexed to AS 7-12.
When calculating the reserves in the mega-complex of productive Neocomian deposits, 11 productive strata were identified: AC12/3, AC12/1-2, AC12/0, AC11/2-4, AC11/1, AC11/0, AC10/2-3, AC10/ 1, AC10/0, AC9, AC7.
The AS 12 reservoir unit lies at the base of the mega-complex and is the deepest part in terms of formation. Three layers AS 12/3, AS 12/1-2, AS 12/0 are identified in the composition, which are separated from each other by relatively consistent clays over most of the area, the thickness of which varies from 4 to 10 m.
The deposits of the AS 12/3 formation are confined to a monoclinal element (structural nose), within which low-amplitude uplifts and depressions with transition zones between them are noted.
The main deposit AS12/3 was discovered at depths of 2620-2755m and is lithologically shielded from all sides. In terms of area, it occupies the central terrace-like, most elevated part of the structural nose and is oriented from the southwest to the northeast. Oil-saturated thickness varies from 12.8m to 1.4m. Oil flow rates range from 1.02 m 3 /day, Hd=1239m to 7.5 m 3 /day at Hd=1327m. The dimensions of the lithologically screened deposit are 25.5 km by 7.5 km, the height is 126 m.
The AS 12/3 deposit was discovered at depths of 2640-2707 m and is confined to the Khanty-Mansiysk local uplift and the zone of its eastern subsidence. The reservoir is controlled from all sides by reservoir replacement zones. Oil production rates are low and amount to 0.4-8.5 m 3 /day at various dynamic levels. The highest mark in the arch is fixed at -2640 m, and the lowest at (-2716 m). The size of the deposit is 18 by 8.5 km, the height is 76m. The type is lithologically shielded.
The main deposit AS12/1-2 is the largest in the field. Revealed at depths of 2536-2728 m. It is confined to a monocline complicated by local uplifts of small amplitude with transition zones between them. On three sides, the structure is limited by lithological screens and only in the south (to the Vostochno-Frolovskaya area) do reservoirs tend to develop. Oil-saturated thicknesses vary in a wide range from 0.8 to 40.6 m, while the zone of maximum thicknesses (more than 12 m) covers the central part of the deposit, as well as the eastern one. The dimensions of the lithologically screened deposit are 45 km by 25 km, the height is 176 m.
In the AS 12/1-2 formation, deposits 7.5 by 7 km, 7 m high and 11 by 4.5 km, 9 m high were discovered. Both deposits are of a lithologically screened type.
The AC 12/0 formation has a smaller development zone. The main deposit AS 12/0 is a lenticular body oriented from the southwest to the northeast. Its dimensions are 41 by 14 km, height is 187 m. Oil rates vary from a few m 3 /day at dynamic levels up to 48 m 3 /day.
The cap of horizon AS 12 is formed by a thick (up to 60 m) stratum of clayey rocks.
Above the section, there is a unit of productive strata AS 11, which includes AS 11/0, AS 11/1, AS 11/2, AS 11/3, AS 11/4. The last three are combined into a single countable object, which has a very complex structure both in terms of section and area. In the reservoir development zones, gravitating towards the near-water areas, the most significant horizon thicknesses are observed with a tendency to increase to the northeast (up to 78.6 m). In the southeast, this horizon is represented only by the AS 11/2 formation, in the central part - by the AS 11/3 formation, in the north - by the AS 11/2-4 formation.
The main deposit AS11/1 is the second largest deposit within the Priobskoye field. The AC11/1 layer is developed in the near-meridional swell-like uplift, which complicates the monocline. On three sides, the deposit is limited by clay zones, and in the south the boundary is drawn conditionally. The size of the main deposit is 48 by 15 km, height is 112 m. Oil rates vary from 2.46 m 3 /day at a dynamic level of 1195 m to 11.8 m 3 /day.
Reservoir AS 11/0 was identified as isolated lenticular bodies in the northeast and south. Its thickness is from 8.6 m to 22.8 m. The first deposit has dimensions of 10.8 by 5.5 km, the second 4.7 by 4.1 km. Both deposits are lithologically shielded type. They are characterized by oil inflows from 4 to 14 m 3 /day at a dynamic level. The AC 10 horizon was discovered by almost all wells and consists of three layers AS 10/2-3, AS 10/1, AS 10/0.
The main AS 10/2-3 deposit was discovered at depths of 2427-2721 m and is located in the southern part of the deposit. The deposit type is lithologically screened, the dimensions are 31 by 11 km, the height is up to 292 m. The oil-saturated thicknesses range from 15.6 m to 0.8 m.
The main deposit AS10/1 was discovered at depths of 2374-2492 m. The size of the deposit is 38 by 13 km, the height is up to 120 m. The southern boundary is drawn conditionally. Oil-saturated thickness varies from 0.4 to 11.8 m. Anhydrous oil inflows ranged from 2.9 m 3 /day at a dynamic level of 1064 m to 6.4m 3 /day.
The section of the AS 10 formation is completed by the productive formation AS 10/0 , within which three deposits have been identified, located in the form of a chain of submeridial strike.
The AC 9 horizon has a limited distribution and is presented in the form of separate fascial zones located in the northeastern and eastern parts of the structure, as well as in the area of the southwestern dip.
The Neocomian productive deposits are completed by the AC 7 layer, which has a mosaic pattern in the distribution of oil and water fields.
The Eastern deposit, the largest in area, was discovered at depths of 2291-2382 m. It is oriented from the southwest to the northeast. Oil inflows are 4.9-6.7 m 3 /day at dynamic levels of 1359-875 m. Oil-saturated thickness varies from 0.8 to 67.8 m. The size of the deposit is 46 by 8.5 km, the height is 91 m.
A total of 42 deposits have been discovered within the field. The main deposit in the AS 12/1-2 formation (1018 km 2) has the maximum area, the minimum (10 km 2) is the deposit in the AS 10/1 formation.
Summary table of reservoir parameters within the production area
Table 1.1
|
depth, m |
Average thickness |
open Porosity. % |
Oil saturation..% |
Coefficient grittiness |
dismemberment |
|||
geological production field oil-bearing reservoir
1.6 Characterizationaquiferscomplexes
The Priobskoye field is part of the hydrodynamic system of the West Siberian artesian basin. Its peculiarity is the presence of water-resistant clay deposits of the Oligocene-Turon, the thickness of which reaches 750 m, dividing the Meso-Cenozoic section into the upper and lower hydrogeological floors.
The upper floor combines Turonian-Quaternary sediments and is characterized by free water exchange. In hydrodynamic terms, the floor is an aquifer, the groundwater and interlayer waters of which are interconnected.
The composition of the upper hydrogeological stage includes three aquifers:
1- Quaternary aquifer;
2 - aquifer of Novomikhailovsky deposits;
3 - aquifer of the Atlym deposits.
A comparative analysis of aquifers showed that the Atlymsky aquifer can be taken as the main source of a large centralized domestic and drinking water supply. However, due to a significant reduction in operating costs, the Novomikhailovsky horizon can be recommended.
The lower hydrogeological stage is represented by Cenomanian-Jurassic deposits and flooded rocks of the upper part of the pre-Jurassic basement. At great depths, in an environment of difficult, and in some places almost stagnant conditions, thermal highly mineralized waters are formed, which have a high gas saturation and an increased concentration of trace elements. The lower floor is distinguished by reliable isolation of aquifers from surface natural and climatic factors. Four water-bearing complexes are distinguished in its section. All complexes and aquicludes can be traced at a considerable distance, but at the same time, claying of the second complex is observed at the Priobskoye field.
Groundwater of the Aptian-Cenomanian complex is widely used for flooding oil reservoirs in the Middle Ob region. Waters are characterized by low corrosivity due to the absence of hydrogen sulfide and oxygen in them.
1.7 Physical and chemicalpropertiesreservoirfluids
Reservoir oils in productive formations AC10, AC11 and AC12 do not have significant differences in their properties. The nature of the change physical properties oil is typical for deposits that do not have access to the surface and are surrounded by marginal water. In the reservoir conditions of oil of medium gas saturation, the saturation pressure is 1.5-2 times lower than the reservoir pressure (high degree of cross-clamping).
Experimental data on the variability of oils along the section of the production facilities of the field indicate a slight heterogeneity of oil within the deposits.
The oils of the AC10, AC11, and AC12 reservoirs are close to each other, the lighter oil in the AC11 reservoir, the molar fraction of methane in it is 24.56%, the total content of hydrocarbons С2Н6 -С5Н12 is 19.85%. Oils of all formations are characterized by the predominance of normal butane and pentane over isomers.
The amount of light hydrocarbons CH4 - C5H12 dissolved in degassed oils is 8.2-9.2%.
Petroleum gas of standard separation is high-fat (fat content more than 50), the mole fraction of methane in it is 56.19 (layer AS10) - 64.29 (layer AS12). The amount of ethane is much less than that of propane, the C2H6 /C3H8 ratio is 0.6, which is typical for the gases of oil deposits. The total content of butanes is 8.1-9.6%, pentanes 2.7-3.2%, heavy hydrocarbons С6Н14 + higher 0.95-1.28%. The amount of carbon dioxide and nitrogen is small, about 1%.
Degassed oils of all formations are sulphurous, paraffinic, low-resinous, of medium density.
The oil of the AC10 reservoir is of medium viscosity, with a content of fractions up to 350_C more than 55%, the oils of the AC11 and AC12 reservoirs are viscous, with a content of fractions up to 350_C from 45% to 54.9%.
Technological code for oils of the AS10-II T1P2 formation, AS11 and AS12-II T2P2 formations.
The estimation of the parameters determined by the individual characteristics of oils and gases was carried out in accordance with the most probable conditions for the collection, preparation and transport of oil in the field.
Separation conditions are as follows:
1 stage - pressure 0.785 MPa, temperature 10_C;
2 stage - pressure 0.687 MPa, temperature 30_C;
3 stage - pressure 0.491 MPa, temperature 40_C;
Stage 4 - pressure 0.103 MPa, temperature 40_C.
Comparison of average values of porosity and reservoir permeabilitylayers AC10-AC12 according to core and logging
Table 1.2
|
samples |
||||||||
1.8 Estimation of oil reserves
Estimation of oil reserves of the Priobskoye field was carried out as a whole for the reservoirs without differentiation by deposits. Due to the absence of formation waters in lithologically limited deposits, the reserves were calculated for purely oil zones.
The balance oil reserves of the Priobskoye field were estimated by the volumetric method.
The basis for calculating reservoir models was the results of logging interpretation. At the same time, the following estimates of reservoir parameters were taken as the boundary values of the reservoir-non-reservoir: K op 0.145, permeability 0.4 mD. From reservoirs and, consequently, from the calculation of reserves, zones of reservoirs were excluded, in which the values of these parameters were less than the standard ones.
When calculating the reserves, the method of multiplying maps of three main calculation parameters was used: effective oil-saturated thickness, open porosity coefficients and oil saturation. The effective oil saturated volume was calculated separately for reserves categories.
The allocation of categories of reserves was made in accordance with the "Classification of reserves of deposits ..." (1983) . Depending on the degree of knowledge of the deposits of the Priobskoye field, the reserves of oil and dissolved gas in them are calculated in categories B, C 1 , C 2 . Category B reserves have been identified within the last wells of production rows on the left-bank drilled section of the field. Reserves of category C 1 were identified in areas studied by exploration wells, in which commercial oil inflows were obtained or there was positive information from well logging. The reserves in the unexplored zones of the deposits were classified as category C 2 . The boundary between categories C 1 and C 2 was drawn at a distance of a double step of the operational grid (500x500 m), as provided for by the "Classification ...".
The estimation of the reserves was completed by multiplying the obtained volumes of oil-saturated reservoirs for each layer and within the selected categories by the density of the oil degassed during the staged separation of oil and the conversion factor. It should be noted that they are somewhat different from those previously accepted. This is due, firstly, to the exclusion from the calculations of wells located far outside the licensed area, and, secondly, to changes in the reservoir indexation in individual exploration wells as a result of a new correlation of productive deposits.
The accepted calculation parameters and the obtained results of the calculation of oil reserves and are given below.
1.8.1 Stocksoil
As of 01.01.98, the VGF reserves of oil are listed in the amount of:
Recoverable 613380 thousand tons.
Recoverable 63718 thousand tons.
Recoverable 677098 thousand tons.
Oil reserves by reservoirs
Table 1.3
|
balance sheet |
balance sheet |
Extract. |
Balance sheet |
Extract. |
||||||
On the drilled section of the left-bank part of the Priobskoye field, the Party of calculating the reserves of Yuganskneftegaz JSC was carried out.
109438 thousand tons are concentrated in the drilled part. balance and 31131 thousand tons. recoverable oil reserves at an oil recovery factor of 0.284.
For the drilled part, the reserves are distributed by layers as follows:
Layer AC10 balance 50%
Retrievable 46%
Plast AS11 balance 15%
Retrievable 21%
Layer AC12 balance 35%
Recoverable 33%
In the territory under consideration, the main volume of reserves is concentrated in the layers AS10 and AS12. This area contains 5.5% of oil reserves. 19.5% of the reserves of the AC10 formation; 2.4% - AC11; 3.9% - AC12.
Priobskoem / r (left-bankpart)
Stocksoilonzoneexploitation
Table 1.4
|
Oil reserves, thousand tons |
CIN shares units. |
||||
|
balance sheet |
recoverable |
||||
*) For part of the territory of category C1, from which oil is produced
2 . Mining methods, equipment used
The development of each production facility AS 10 , AS 11 , AS 12 was carried out with the placement of wells according to a linear three-row triangular pattern with a grid density of 25 ha/well, with drilling of all wells up to the AS 12 formation.
In 2007, SibNIINP prepared an "Addendum to technological scheme pilot development of the left-bank part of the Priobskoye field, including the floodplain section N4", in which adjustments were made for the development of the left-bank part of the field with the connection to the work of new pads N140 and 141 in the floodplain part of the field. In accordance with this document, the implementation of a block three-row system ( grid density - 25 ha/well) with the transition in the future at a later stage of development to a block-closed system.
The dynamics of the main technical and economic indicators of development is presented in Table 2.1
2. 1 DynamicsmajorindicatorsdevelopmentPriobskyPlace of Birth
table 2.1
2. 2 Analysismajortechnical and economicindicatorsdevelopment
The dynamics of development indicators based on Table 2.1 is shown in fig. 2.1.
The Priobskoye field has been developed since 1988. Over the 12 years of development, as can be seen from Table 3, oil production has been constantly growing.
If in 1988 it was 2300 tons of oil, then by 2010 it reached 1485000 tons, the production of liquid increased from 2300 to 1608000 tons.
Thus, by 2010, the cumulative oil production amounted to 8583.3 thousand tons. (table 3.1) .
Since 1991, to maintain reservoir pressure, injection wells have been put into operation and water injection has begun. At the end of 2010, the injection well stock was 132 wells, and water injection increased from 100 to 2362 thousand tons. by 2010. With an increase in injection, the average flow rate of operating wells for oil increases. By 2010, the flow rate is increasing, which is explained by the right choice the amount of water injected.
Also, since the commissioning of the injection fund, the growth of water cut in production begins and by 2010 it reaches 9.8%, the first 5 years the water cut is 0%.
By 2010, the stock of producing wells amounted to 414 wells, of which 373 wells producing products by mechanized method By 2010, the cumulative oil production amounted to 8583.3 thousand tons. (table 2.1) .
The Priobskoye field is one of the youngest and most promising in Western Siberia.
2.3 Peculiaritiesdevelopment,influencingon theexploitationwells
The field is characterized by low well flow rates. The main problems in the development of the field were low productivity of production wells, low natural (without fracturing the formations with injected water) injectivity of injection wells, as well as poor redistribution of pressure over the deposits during the reservoir pressure maintenance (due to the weak hydrodynamic connection of individual sections of the reservoirs). The exploitation of the AS 12 formation should be singled out as a separate problem of field development. Due to low flow rates, many wells in this formation must be shut down, which may lead to the conservation of significant oil reserves indefinitely. One of the directions for solving this problem in the AS 12 formation is the implementation of measures to intensify oil production.
The Priobskoye field is characterized by a complex structure of productive horizons both in terms of area and section. The reservoirs of horizons AS 10 and AS 11 are medium and low productive, and AS 12 are abnormally low productive.
The geological and physical characteristics of the productive strata of the field indicate the impossibility of developing the field without actively influencing its productive strata and without using methods of production intensification.
This confirms the experience of developing the operational section of the left-bank part.
3 . Applied methods of enhanced oil recovery
3.1 Choicemethodimpacton theoildeposit
The choice of a method for influencing oil deposits is determined by a number of factors, the most significant of which are the geological and physical characteristics of the deposits, the technological possibilities of implementing the method in a given field, and economic criteria. The methods of formation stimulation listed above have numerous modifications and, at their core, are based on a huge set of compositions of the working agents used. Therefore, when analyzing existing stimulation methods, it makes sense, first of all, to use the experience of developing fields in Western Siberia, as well as fields in other regions with reservoir properties similar to the Priobskoye field (primarily low reservoir permeability) and formation fluids.
Of the methods of intensifying oil production by influencing the bottomhole zone of the well, the most widely used are:
hydraulic fracturing;
acid treatments;
physical and chemical treatments with various reagents;
thermophysical and thermo-chemical treatments;
pulse-impact, vibroacoustic and acoustic impact.
3.2 Geological and physical criteria for the applicability of various stimulation methods in the Priobskoye field
The main geological and physical characteristics of the Priobskoye field for assessing the applicability of various impact methods are:
depth of productive layers - 2400-2600 m,
the deposits are lithologically screened, the natural regime is elastic closed,
the thickness of the AS 10, AS 11 and AS 12 seams is up to 20.6, 42.6 and 40.6 m, respectively.
initial reservoir pressure - 23.5-25 MPa,
reservoir temperature - 88-90 0 С,
low reservoir permeability, average values according to the results of the core study - for the layers AC 10, AC 11 and AC 12, respectively, 15.4, 25.8, 2.4 mD,
high lateral and vertical reservoir heterogeneity,
reservoir oil density - 780-800 kg / m 3,
formation oil viscosity - 1.4-1.6 mPa*s,
oil saturation pressure 9-11 MPa,
oil of the naphthenic series, paraffinic and low-resinous.
Comparing the presented data with the known criteria for the effective use of reservoir stimulation methods, it can be noted that, even without a detailed analysis, thermal methods and polymer flooding (as a method of oil displacement from reservoirs) can be excluded from the above methods for the Priobskoye field. Thermal methods are used for reservoirs with high-viscosity oils and at depths up to 1500-1700 m. Polymer flooding is preferably used in reservoirs with a permeability of more than 0.1 µm 2 to displace oil with a viscosity of 10 to 100 mPa * s and at temperatures up to 90 0 С ( for higher temperatures, expensive, special polymers are used).
3.2.1 Water flooding
Experience in the development of domestic and foreign fields shows that waterflooding is a fairly effective method of influencing low-permeability reservoirs with strict observance of the necessary requirements for the technology of its implementation.
Among the main reasons causing a decrease in the efficiency of waterflooding of low-permeability formations are:
deterioration of the filtration properties of the rock due to:
swelling of the clay components of the rock upon contact with the injected water,
clogging of the collector with fine mechanical impurities in the injected water,
precipitation of salt deposits in the porous medium of the reservoir during the chemical interaction of injected and formation water,
reduction of reservoir coverage by flooding due to the formation of fractures around the injection wells and their propagation into the depth of the reservoir (for discontinuous reservoirs, some increase in reservoir coverage along the section is also possible),
Significant sensitivity to the nature of rock wettability by the injected agent Significant reduction in reservoir permeability due to paraffin precipitation.
The manifestation of all these phenomena in low-permeability reservoirs causes more significant consequences than in high-permeability rocks.
To eliminate the influence of these factors on the flooding process, appropriate technological solutions are used: optimal well patterns and technological modes of well operation, injection of water of the required type and composition into the reservoirs, its appropriate mechanical, chemical and biological treatment, as well as the addition of special components to the water.
For the Priobskoye field, flooding should be considered as the main treatment method.
The use of surfactant solutions at the field was rejected, primarily due to the low efficiency of these reagents in low-permeability reservoirs.
For the Priobskoye field and alkaline flooding cannot be recommended for the following reasons:
The main one is the predominant structural and layered clay content of the reservoirs. Clay aggregates are represented by kaolinite, chlorite and hydromica. The interaction of alkali with clay material can lead not only to swelling of the clay, but also to the destruction of the rock. An alkaline solution of low concentration increases the swelling coefficient of clays by 1.1-1.3 times and reduces the permeability of the rock by 1.5-2 times compared to fresh water, which is critical for low-permeability reservoirs of the Priobskoye field. The use of solutions of high concentration (reducing the swelling of clays) activates the process of destruction of the rock. In addition, high ion exchanger clays can adversely affect the liquor slug by exchanging sodium for hydrogen.
Strongly developed formation heterogeneity and a large number of interlayers, leading to low formation coverage with alkali solution.
The main obstacle to the use emulsion systems for the impact on the deposits of the Priobskoye field are the low filtration characteristics of the reservoirs of the field. The filtration resistance created by emulsions in low-permeability reservoirs will lead to a sharp decrease in the injectivity of injection wells and a decrease in the rate of oil recovery.
3.3 Methods of influencing the bottomhole formation zone to stimulate production
3.3.1 Acid treatments
Acid treatment of formations is carried out both to increase and to restore the permeability of the reservoir of the bottomhole zone of the well. Most of these works were carried out during the transfer of wells to injection and subsequent increase in their injectivity.
Standard acid treatment at the Priobskoye field consists in preparing a solution consisting of 14% HCl and 5% HF, with a volume of 1.2-1.7 m 3 per 1 meter of perforated formation thickness and pumping it into the perforation interval. The response time is about 8 hours.
When considering the effectiveness of the impact of inorganic acids, injection wells with long-term (more than one year) water injection before treatment were taken into account. As an example, Table 3.1 presents the results of treatments for a number of injection wells.
Treatment results in injection wells
Table 3.1
|
date of processing |
Injectivity before processing (m 3 / day) |
Injectivity after treatment (m 3 / day) |
Injection pressure (atm) |
Acid type |
||
The analysis of the treatments performed shows that the composition of hydrochloric and hydrofluoric acid improves the permeability of the wellbore zone. The injectivity of wells increased from 1.5 to 10 times, the effect can be traced from 3 months to 1 year.
Thus, based on the analysis of the acid treatments carried out at the field, it can be concluded that it is expedient to carry out acid treatments of the bottomhole zones of injection wells in order to restore their injectivity.
3.3.2 Hydraulic fracturing
Hydraulic fracturing (HF) is one of the most effective methods intensification of oil production from low-permeability reservoirs and increase in the production of oil reserves. Hydraulic fracturing is widely used both in domestic and foreign oil production practice.
Significant hydraulic fracturing experience has already been accumulated at the Priobskoye field. The analysis performed at the hydraulic fracturing field indicates the high efficiency of this type of production stimulation for the field, despite the significant rate of production decline after hydraulic fracturing. Hydraulic fracturing in the case of the Priobskoye field is not only a method of intensifying production, but also increasing oil recovery. Firstly, hydraulic fracturing allows you to connect non-drained oil reserves in intermittent reservoirs of the field. Secondly, this species impact allows you to select an additional volume of oil from the low-permeability formation AS 12 for an acceptable time of field operation.
Gradeadditionalpreyfromholdinghydraulic fracturingon thePriobskyfield.
The introduction of the hydraulic fracturing method at the Priobskoye field began in 2006, as one of the most recommended stimulation methods in these development conditions.
During the period from 2006 to January 2011, 263 hydraulic fracturing operations were carried out at the field (61% of the fund). The main number of hydraulic fracturing was carried out in 2008 - 126.
At the end of 2008, additional oil production due to hydraulic fracturing already amounted to about 48% of all oil produced during the year. Moreover, most of the additional production was oil from the AS-12 reservoir - 78.8% of the total production from the reservoir and 32.4% of the production as a whole. For the AC11 reservoir - 30.8% of the total production for the reservoir and 4.6% of the production in general. For the AC10 reservoir - 40.5% of the total production for the reservoir and 11.3% of the production in general.
As can be seen, the main target for hydraulic fracturing was the AS-12 formation as the most low-productive and containing most of the oil reserves in the left-bank zone of the field
At the end of 2010, additional oil production due to hydraulic fracturing amounted to more than 44% of oil production from all oil produced during the year.
The dynamics of oil production for the field as a whole, as well as additional oil production due to hydraulic fracturing, is presented in Table 3.2
Table 3.2
A significant increase in oil production due to hydraulic fracturing is evident. Since 2006, additional production from hydraulic fracturing has amounted to 4,900 tons. Every year, the increase in production from hydraulic fracturing is growing. The maximum growth value is 2009 (701,000 tons). By 2010, the value of additional production drops to 606,000 tons, which is 5,000 tons lower than in 2008.
Thus, hydraulic fracturing should be considered the main way to increase oil recovery at the Priobskoye field.
3.3.3 Improving perforation efficiency
An additional means of increasing the productivity of wells is the improvement of perforation operations, as well as the formation of additional filtration channels during perforation.
Improvement in CCD perforation can be achieved by using more powerful perforation charges to increase perforation depth, increase perforation density, and use phasing.
The methods of creating additional filtration channels can include, for example, the technology of creating a system of cracks during the secondary opening of the reservoir with perforators on pipes - the system of fractured perforation of the reservoir (FSPP).
This technology was first used by Marathon (Texas, USA) in 2006. Its essence lies in the perforation of the productive formation with powerful 85.7 mm perforators with a density of about 20 holes per meter during repression on the formation, followed by fixing the perforation channels and cracks with a proppant - bauxite fraction from 0.42 to 1.19 mm.
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The Priobskoye oil and gas field is geographically located on the territory of the Khanty-Mansiysk Autonomous District of the Tyumen Region of the Russian Federation. The city closest to the Priobskoye field is Nefteyugansk (located 200 km east of the field).
The Priobskoye field was discovered in 1982. The field is characterized as multi-layer, low-productive. The territory is cut by the Ob River, swampy and mostly flooded during the flood period; here are spawning grounds for fish. As noted in the materials of the Ministry of Fuel and Energy of the Russian Federation submitted to the State Duma, these factors complicate the development and require significant financial resources to apply the latest highly efficient and environmentally friendly technologies.
The license for the development of the Priobskoye field belongs to a subsidiary of OAO Rosneft, the company Rosneft-Yuganskneftegaz.
According to specialists' calculations, the development of the deposit under the existing taxation system is unprofitable and impossible. Under the terms of the PSA, oil production over 20 years will amount to 274.3 million tons, state income - $48.7 billion.
The recoverable reserves of the Priobskoye field are 578 million tons of oil, gas - 37 billion cubic meters. The development period under the PSA is 58 years. Peak production level - 19.9 million tons. tons in the 16th year of development. Initial funding was planned at $1.3 billion. Capital costs - 28 billion dollars, operating costs - 27.28 billion dollars. Probable directions of oil transportation from the field are Ventspils, Novorossiysk, Odessa, Druzhba.
The possibility of joint development of the northern part of the Priobskoye field was discussed by Yugansneftegaz and Amoso in 1991. In 1993, Amoso took part in an international tender for the right to use the subsoil in the fields of the Khanty-Mansi Autonomous Okrug and was recognized as the winner of the competition for the exclusive right to become a foreign partner in the development of the Priobskoye field together with Yuganskneftegaz.
In 1994, Yuganskneftegaz and Amoso prepared and submitted to the government a draft agreement on production sharing and Tenico-economic and environmental justification of the project.
In early 1995, an additional feasibility study was submitted to the government, which was amended in the same year in the light of new data on the deposit.
In 1995, the Central Commission for the Development of Oil and Oil and Gas Fields of the Ministry of Fuel and Energy of the Russian Federation and the Ministry of Protection environment and Natural Resources of the Russian Federation approved an updated scheme for the development of the field and the environmental part of the pre-project documentation.
On March 7, 1995, the then Prime Minister Viktor Chernomyrdin issued an order on the formation of a government delegation from representatives of the Khanty-Mansi Autonomous Okrug and a number of ministries and departments to negotiate a PSA in the development of the northern part of the Priobskoye field.
In July 1996, in Moscow, a joint Russian-American commission on economic and technical cooperation issued a joint statement on the priority of projects in the energy field, among which the Priobskoye field was specifically named. The joint statement indicates that both governments welcome the commitment to conclude a production sharing agreement for this project by the next meeting of the commission in February 1997.
At the end of 1998, Yuganskneftegaz's partner in the Priobskoye field development project, the American company Amoso, was taken over by the British company British Petroleum.
In early 1999, BP/Amoso officially announced its withdrawal from participation in the Priobskoye field development project.
Ethnic history of the Priobskoye deposit
Since ancient times, the area of the deposit was inhabited by the Khanty. The Khanty developed complex social systems, called principalities and by the XI-XII centuries. they had large tribal settlements with fortified capitals, which were ruled by princes and defended by professional troops.
The first known contacts of Russia with this territory took place in the 10th or 11th century. At this time, trade relations began to develop between the Russians and the indigenous population of Western Siberia, which brought cultural change into the life of the aborigines. Iron and ceramic household utensils and fabrics appeared and became a material part of the life of the Khanty. The fur trade acquired great importance as a means of obtaining these goods.
In 1581 Western Siberia was annexed to Russia. The princes were replaced by the tsarist government, and taxes were paid into the Russian treasury. In the 17th century, tsarist officials and servicemen (Cossacks) began to settle in this territory, and contacts between Russians and Khanty gained further development. As a result of closer contacts, Russians and Khanty began to adopt the attributes of each other's way of life. The Khanty began to use guns and traps, some, following the example of the Russians, took up the breeding of cattle and horses. The Russians borrowed some hunting and fishing techniques from the Khanty. The Russians acquired lands and fishing grounds from the Khanty, and by the 18th century most of the Khanty land had been sold to Russian settlers. Russian cultural influence expanded in the early 18th century with the introduction of Christianity. At the same time, the number of Russians continued to increase, and by the end of the 18th century, the Russian population in this area outnumbered the Khanty by five times. Most of the Khanty families borrowed knowledge from the Russians Agriculture, cattle breeding and horticulture.
The assimilation of the Khanty into Russian culture accelerated with the establishment of Soviet power in 1920. The Soviet policy of social integration brought to the region single system education. Khanty children were usually sent from families to boarding schools for a period of 8 to 10 years. Many of them, after graduating from school, could no longer return to the traditional way of life without having the necessary skills for this.
The collectivization that began in the 1920s had a significant impact on the ethnographic character of the territory. In the 50-60s, the formation of large collective farms began and several small settlements disappeared as the population united into larger settlements. By the 1950s, mixed marriages between Russians and Khanty became widespread, and almost all Khanty born after the 1950s were born in mixed marriages. Since the 1960s, as Russians, Ukrainians, Belarusians, Moldavians, Chuvashs, Bashkirs, Avars and representatives of other nationalities migrated to the region, the percentage of Khanty decreased even more. Currently, the Khanty make up a little less than 1 percent of the population of the Khanty-Mansi Autonomous Okrug.
In addition to the Khanty, the Mansi (33%), Nenets (6%) and Selkups (less than 1%) live on the territory of the Priobskoye field.
The Priobskoye oil field was discovered in 1982 by well No. 151 of Glavtyumengeologiya.
Refers to the distributed subsoil fund. The license was registered by OOO Yuganskneftgegaz and NK Sibneft-Yugra in 1999. It is located on the border of the Salym and Lyaminsky oil and gas regions and is confined to the local structure of the same name in the Sredneobskaya oil and gas region. According to the reflecting horizon "B", the rise is contoured by an isoline - 2890 m and has an area of 400 km2. The foundation was opened by borehole No. 409 in the depth interval 3212 - 3340 m and is represented by metamorphoses. rocks of greenish color. Lower Jurassic deposits lie on it with angular unconformity and erosion. The main platform section is composed of Jurassic and Cretaceous deposits. The Paleogene is represented by the Danish Stage, Paleocene, Eocene and Oligocene. The thickness of the Quaternary deposits reaches 50 m. The bottom of permafrost is noted at a depth of 280 m, the roof - at a depth of 100 m. yuteriva and barrel lenses. The reservoir is granular sandstones with interlayers of clays. Belongs to the unique class.
