Priobskoye deposit. Priobskoye oil field South Priobskoye field how to get there
New technologies and a competent policy of Yuganskneftegaz have improved the condition of the Priobskoye oil field, whose geological reserves are at the level of 5 billion tons of oil.
Priobskoye NM is a giant oil field in Russia. This hard-to-reach and remote field is located 70 km from the city of Khanty-Mansiysk and 200 kilometers from the city of Nefteyugansk. It is included in the West Siberian oil and gas province. About 80% of the Priobsky NM is located directly in the floodplain of the Ob River and is divided by water into two parts. A feature of Priobskoye is flooding during periods of floods.
Main geological and physical characteristics of the deposit
A distinctive feature of the Priobskoye is a complicated geological structure, characterized by multi-strata and a low degree of productivity. The reservoirs of the main productive formations are characterized by low permeability, low net-to-gross ratio, high level of clay content and high dissection. These factors suggest the use of hydraulic fracturing technologies in the development process.
The location of the deposits is not deeper than 2.6 km. Oil density indicators are 0.86–0.87 tons per m³. The amount of paraffins is moderate and does not exceed 2.6%, the amount of sulfur is about 1.35%.
The field is classified as sour and has class II oil in accordance with GOST for refineries.The deposits are lithologically screened and have the elasticity and isolation of the natural regime. The reservoir thickness indicators range from 0.02 to 0.04 km. The formation pressure has initial values of 23.5–25 MPa. The temperature regime of the reservoirs remains in the range of 88–90°С. The reservoir type of oil has stable viscosity parameters and has a dynamic coefficient of 1.6 MPa s, as well as the effect of oil saturation at a pressure of 11 MPa.
The presence of paraffin content and low resin content of the naphthenic series are characteristic. The initial daily volume of operating oil wells varies from 35 to 180 tons. The type of wells is based on the cluster location, and the maximum recovery factor is 0.35 units. The Priobskoye oilfield produces crude oil with a significant amount of light hydrocarbons, which entails the need to stabilize or separate APG.
Start of development and stocks
Priobskoe NM was opened in 1982. In 1988, the development of the left-bank part of the field began, and eleven years later, the development of the right bank began.
The amount of geological reserves is 5 billion tons, and the proven and recoverable amount is estimated at almost 2.5 billion tons.
Features of production at the field
The duration of development under the terms of the Production Sharing Agreement was assumed to be no more than 58 years. The maximum level of oil production is almost 20 million tons in 16 years from the moment of development.
Financing at the initial stage was planned at the level of $1.3 billion. The capital expenditure accounted for $28 billion, and the cost of operational work amounted to $27.28 billion. It was planned to attract the Latvian city of Ventspils, Odessa, Novorossiysk.
According to 2005 data, the field has 954 production wells and 376 injection wells.Companies developing the field
In 1991, Yuganskneftegaz and Amoso began discussing the prospects of joint developments in the northern 
the bank of the NM Priobskoye.
In 1993, the Amoso company won the competition and received the exclusive right to develop the Priobskoye oilfield together with Yuganskneftegaz. A year later, the companies prepared and submitted to the government a project agreement on the distribution of products, as well as an environmental and feasibility study of the developed project.
In 1995, the government got acquainted with an additional feasibility study, which reflected new data on the Priobskoye field. By order of the Prime Minister, a government delegation was formed, including representatives of the Khanty-Mansi Autonomous Okrug, as well as some ministries and departments, in order to negotiate a Production Sharing Agreement in the context of the development of the northern segment of the Priobskoye field.
In the middle of 1996, a statement was heard in Moscow by a joint Russian-American commission on the priority of design innovations in the energy industry, including on the territory of the Priobskoye oilfield.
In 1998, the partner of Yuganskneftegaz in the development of NM Priobskoye, the American company Amoso, was taken over by the British company British Petroleum, and an official statement was received from BP / Amoso about the termination of participation in the project for the development of the Priobskoye field.
Then a subsidiary of the state company Rosneft, which received control over the central asset of Yukos, Yuganskneftegaz, LLC RN-Yuganskneftegaz, was involved in the development of the field.
In 2006, specialists from NM Priobskoye and Newco Well Service performed the largest hydraulic fracturing of an oil reservoir in the Russian Federation, into which 864 tons of proppant were pumped. The operation lasted seven hours, the live broadcast could be watched through the Internet office of Yuganskneftegaz.Currently, RN-Yuganskneftegaz LLC is working steadily on the development of the northern part of the Priobskoye oil field, and Gazpromneft-Khantos LLC, which belongs to Gazpromneft, is developing the southern segment of the field. The southern segment of the Priobskoye NM has license areas that are insignificant in area. The development of the Sredne-Shapshinskiy and Verkhne-Shapshinskiy segments has been carried out since 2008 by NAK AKI OTYR, which belongs to OAO Russneft.
Prospects for the Priobsky NM
A year ago, Gazpromneft-Khantos became the owner of a license to conduct a geological study of parameters related to deep oil-saturated horizons. The southern part of the NM Priobskoe, including the Bazhenov and Achimov formations, is subject to study.
Last year was marked by the analysis of geographical data on the territory of the Bazheno-Abalaksky complex of the Yuzhno-Priobsky oilfield. The combination of specialized core analysis and evaluation of this class of reserves involves the drilling of four deviated prospecting and appraisal wells.
Horizontal wells will be drilled in 2016. To estimate the volume of recoverable reserves, a multi-stage hydraulic fracturing is envisaged.
The impact of the deposit on the ecology of the area
The main factors affecting the environmental situation in the area of the deposit are the presence of emissions into the atmosphere. 
layers. These emissions are petroleum gas, products of combustion of oil, components of evaporation from light hydrocarbon fractions. In addition, spills of oil products and components onto the soil are observed.
The unique territorial feature of the deposit is due to its location on floodplain river landscapes and within the water protection zone. Making special demands on development is based on high value. In this situation, floodplain lands are considered, with characteristic high dynamism and complex hydrological regime. This territory was chosen for nesting by migratory birds of semiaquatic species, many of which are included in the Red Book. The deposit is located on the territory of migration routes and wintering grounds for many rare representatives of the ichthyofauna.
Even 20 years ago, the Central Commission for the development of NM and NGM under the Ministry of Fuel and Energy of Russia, as well as the Ministry for Environmental Protection and Natural Resources of Russia, approved the exact scheme for the development of NM Priobskoye and the environmental part of all preliminary design documentation.
The Priobskoye deposit is cut into two parts by the Ob River. It is swampy and during the flood most of it is flooded. It was these conditions that contributed to the formation of fish spawning grounds on the territory of the NM. The Ministry of Fuel and Energy of Russia submitted materials to the State Duma, on the basis of which a conclusion was made about the complication of the development of the Priobskoye oilfield due to the existing natural factors. Such documents confirm the need for additional financial resources in order to use only the latest and environmentally friendly technologies in the field, which will allow highly efficient implementation of environmental protection measures.
Priobskoye is a giant oil field in Russia.
Located in the Khanty-Mansiysk Autonomous Okrug, near Khanty-Mansiysk. Opened in 1982. 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 - in 1999.
Geological reserves are estimated at 5 billion tons. Proved and recoverable reserves are estimated at 2.4 billion tons.
The field belongs to the West Siberian oil and gas province. Opened in 1982. Deposits at a depth of 2.3-2.6 km. Oil density 863-868 kg/m³, moderate paraffin content (2.4-2.5%) and sulfur content 1.2-1.3%.
As of the end of 2005, there were 954 producing and 376 injection wells in the field, of which 178 wells were drilled during the last year.
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.
At present, the northern part of the field (SLT) is being developed by RN-Yuganskneftegaz LLC, owned by Rosneft, and the southern part (YULT) is being developed by Gazpromneft-Khantos LLC, owned by Gazprom Neft. Also, in the south of the field, there are relatively small Verkhne-Shapshinskiy and Sredne-Shapshinskiy license blocks, which have been developed since 2008 by NAK AKI OTYR, owned by JSC Russneft.
At the beginning of November 2006, the largest in Russia hydraulic fracturing of an oil reservoir. 864 tons of proppant were pumped into the reservoir. The operation lasted seven hours and was broadcast live via the Internet to the office of Yuganskneftegaz.
Priobskoye oil field
§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 is widely used 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)
The initial flow rate of operating oil wells is from 35 tons / 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 site, 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 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 the bottoms 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 (an 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, the above methods for the Priobskoye field can be excluded from the above: thermal methods and polymer flooding (as a method of oil displacement from reservoirs). 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).
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Search and evaluation of reservoirs in the sediments of the Aptian-Albian-Cenomanian aquifer for injection of drilling waste, industrial and domestic wastewater in the southern part of the Priobskoye field.
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3D seismic survey in the Eastern area of the southern part of the Priobskoye field (season 2011-2012). in the amount of 150 sq. km.
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Geological report Year of compilation - 2010
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Geological report Year of compilation - 2009
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Priobskoye oil field
| §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 is widely used 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)
The initial flow rate of operating oil wells is from 35 tons / 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 site, 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 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 the bottoms 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 (an 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, the above methods for the Priobskoye field can be excluded from the above: thermal methods and polymer flooding (as a method of oil displacement from reservoirs). 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 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 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.
After reviewing the technologies available on the Russian market and the results of their implementation, the specialists of Gazpromneft-Khantos LLC 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 formation, 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, we can note the successful implementation of foam hydraulic fracturing using nitrogen in the wells of the AC10 and AC12 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 performed. 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 field, 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 facilities 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 intended for infield 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 a 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 Great Britain 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 successively passes through electric dehydrators 5 and 6, in which the bulk of 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.
The fuel oil is pumped by a pump through a system of heat exchangers into a tubular 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 furnace for heating raw materials, 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 is used to simultaneously obtain a high-octane base component of motor gasolines, aromatic hydrocarbons and hydrogen-containing gas.
For Priobskoy oil, the reforming is carried out on the fraction that boils away in the range of 85-180 0 C, and an increase in the end of the boiling point promotes coke formation and is therefore undesirable.
Preparation of reforming feedstock - rectification to separate fractions, hydrotreatment 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 reforming catalysts and, consequently, the need for its efficient use. This is facilitated by the use of alumina as a carrier, which has long been known as the best carrier 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
