Geology of the Priobskoe deposit (Priobka)

Now LLC RN-Yuganskneftegaz is steadily working on the development of the northern part of the Priobskoye oil field, and the development of the southern segment of the field is being carried out by Gazpromneft-Khantos LLC, which belongs to the Gazpromneft company. The southern segment of the Priobskoe oil field has small licensed areas. Since 2008, the development of the Sredne-Shapshinsky and Verkhne-Shapshinsky segments has been carried out by NAC AKI OTYR, which belongs to OJSC Russneft.

Prospects for Priobskoye NM

A year ago, the Gazpromneft-Khantos company became the owner of a license to conduct geological research of parameters related to deep oil-saturated horizons. The southern part of the Priobskoye oil deposit, including the Bazhenov and Achimov formations, is subject to research.

Last year was marked by the analysis of geographic data on the territory of the Bazheno-Abalak complex of the South Priobsky oil field. A set of specialized core analysis and assessment of this class of reserves involves the procedure of drilling four exploration and appraisal wells with an inclined direction.

Horizontal wells will be drilled in 2016. To estimate the volume of recoverable reserves, multi-stage hydraulic fracturing is planned.

Impact of the deposit on the ecology of the area

The main factors influencing the environmental situation in the field area are the presence of emissions into the atmosphere layers. These emissions include petroleum gas, oil combustion products, and 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 specific development requirements is based on high value. In this situation, floodplain lands are considered, with characteristic high dynamism and complex hydrological regime. This territory is chosen for nesting by migratory birds of semi-aquatic 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 ichthyofauna.

Even 20 years ago, the Central Commission for the Development of NM and GPS under the Ministry of Fuel and Energy of Russia, as well as the Ministry of Environmental Protection and Natural Resources of Russia, approved the exact scheme for the development of the Priobskoye NM 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 a flood, most of it is flooded. It was precisely 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 presented materials to the State Duma, on the basis of which it was concluded that the development of the Priobskoye oil pipeline is complicated due to existing natural factors. Such documents confirm the need for additional financial resources in order to use only the latest and environmentally friendly technologies on the territory of the field, which will allow highly efficient implementation of environmental protection measures.

The Priobskoye field appeared on the map of the Khanty-Mansi Autonomous Okrug in 1985, when its left bank part was discovered with well number 181. Geologists received a gush of oil with a volume of 58 cubic meters per day. Four years later, drilling began on the left bank, and commercial operation of the first well on the right bank of the river began 10 years later.

Priobskoye field characteristics

The Priobskoye field lies close to the borders of the oil and gas bearing regions of Salymsky and Lyaminsky.

The characteristics of the oil from the Priobskoye field make it possible to classify it as low-resin (paraffins at the level of 2.4-2.5 percent), but at the same time with a high sulfur content (1.2-1.3 percent), which requires additional purification and reduces profitability. The viscosity of reservoir oil is at the level of 1.4-1.6 mPa*s, and the thickness of the layers reaches from 2 to 40 meters.

The Priobskoye field, whose characteristics are unique, has geologically justified reserves of five billion tons. Of these, 2.4 billion are classified as proven and recoverable. As of 2013, the estimate of recoverable reserves at the Priobskoye field was over 820 million tons.

By 2005, daily production reached high figures - 60.2 thousand tons per day. In 2007, over 40 million tons were produced.

To date, about a thousand production wells and almost 400 injection wells have been drilled at the field. The reservoir deposits of the Priobskoye oil field are located at a depth of 2,3,2,6 kilometers.

In 2007, the annual production of liquid hydrocarbons at the Priobskoye field reached 33.6 million tons (or more than 7% of all production in Russia).

Priobskoye oil field: development features

The peculiarity of drilling is that the bushes of the Priobskoye field are located on both sides of the Ob River and most of them are located in the river floodplain. On this basis, the Priobskoye deposit is divided into South- and North-Priobskoye. In the spring and autumn, the field area is regularly flooded with flood waters.

This arrangement is the reason that its parts have different owners.

On the northern bank of the river, development is carried out by Yuganskneftegaz (a structure that passed to Rosneft after YUKOS), and on the southern bank there are areas that are being developed by the Khantos company, a structure of Gazprom Neft (in addition to Priobsky, it is also involved in the Palyanovsky project). In the southern part of the Priobskoye field, Russneft’s subsidiary, the Aki Otyr company, has been allocated small license areas for the Verkhne- and Sredne-Shapshinsky areas.

These factors, along with the complex geological structure (multiple layers and low productivity), make it possible to characterize the Priobskoye field as difficult to access.

But modern hydraulic fracturing technologies, by pumping large amounts of water mixture underground, can overcome this difficulty. Therefore, all newly drilled pads of the Priobskoye field begin to be exploited only with hydraulic fracturing, which significantly reduces operating costs and capital investments.

In this case, three oil layers are fracturing simultaneously. In addition, the main part of the wells is laid using the progressive cluster method, when lateral wells are directed at different angles. In cross-section, it resembles a bush with branches pointing downwards. This method saves on the arrangement of surface drilling sites.

The cluster drilling technique has become widespread because it allows preserving the fertile soil layer and only has a minor impact on the environment.

Priobskoye field on the map

The Priobskoye field on the map of Khanty-Mansi Autonomous Okrug is determined using the following coordinates:

• 61°20′00″ north latitude,
• 70°18′50″E.

The Priobskoye oil field is located just 65 km from the capital of the Autonomous Okrug - Khanty-Mansiysk and 200 kilometers from the city of Nefteyugansk. In the field development area there are areas with settlements of indigenous small nations:

• Khanty (about half the population),
• Nenets,
• Muncie,
• Selkups.

Several natural reserves have been formed in the area, including Elizarovsky (republican significance), Vaspukholsky, and Shapshinsky cedar forest. Since 2008, in the Khanty-Mansi Autonomous Okrug - Yugra (the historical name of the area with its center in Samarovo), a natural monument “Lugovskie Mammoths” was established with an area of ​​161.2 hectares, on the site of which fossil remains of mammoths and hunting tools dating back from 10 to 15 thousand years were repeatedly found. back.

Oil fields of Russia
http://www.kommersant.ru/doc-rss.aspx?DocsID=1022611

The northern three quarters of the field was controlled by YUKOS via an its daughter-company Yuganskneftegaz, and began oil production in 2000. In 2004 Yuganskneftegaz was bought by Rosneft, which is now the operating company for that portion of the field. The southern quarter of the field was controlled by Sibir energy, which began a joint venture with Sibneft to develop the field, with volume production beginning in 2003. Sibneft subsequently acquired complete control of the field via a corporate maneuver to dilute Sibir's holding. Sibneft is now majority controlled by Gazprom and renamed Gazprom Neft.
http://en.wikipedia.org/wiki/Priobskoye_field

Priobskoye field (KhMAO)
Reserves, million tons
ABC1 - 1061.5
C2 - 169.9
Production in 2007, million tons - 33.6

For many years, the Samotlor field was the largest in terms of both reserves and oil production volumes. In 2007, for the first time it lost first place to the Priobskoye field, oil production from which reached 33.6 million tons (7.1% of Russian production), and proven reserves increased compared to 2006 by almost 100 million tons (taking into account redemption at production).
http://www.mineral.ru/Facts/russia/131/288/index.html

Abdulmazitov R.D. Geology and development of the largest and unique oil and oil and gas fields in Russia.
http://geofizik.far.ru/book/geol/geol009.htm
http://rutracker.org/forum/viewtopic.php?t=1726082

http://www.twirpx.com/file/141095/
http://heriot-watt.ru/t2588.html

Priobskoye is a giant oil field in Russia. Located in the Khanty-Mansiysk Autonomous Okrug, near Khanty-Mansiysk. Opened in 1982. Divided by the Ob River into two parts - left and right banks. Development of the left bank began in 1988, the right - in 1999.

Geological reserves are estimated at 5 billion tons. Proven and recoverable reserves are estimated at 2.4 billion tons.

The deposit belongs to the West Siberian province. Opened in 1982. Deposits at a depth of 2.3-2.6 km. Oil density is 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 are 954 production and 376 injection wells in the field, of which 178 wells were drilled over the past 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.

Currently, the development of the northern part of the field is carried out by RN-Yuganskneftegaz LLC, owned by Rosneft, and the southern part by Gazpromneft-Khantos LLC, owned by Gazprom Neft.
http://ru.wikipedia.org/wiki/Priobskoye_oil_field

http://www.blackbourn.co.uk/databases/hydrocarbon-province-maps/west-siberia.pdf

PRIOBSKOE: THERE ARE 100 MILLION! (Rosneft: Company Bulletin, September 2006) -
On May 1, 1985, the first exploration well was drilled at the Priobskoye field. In September 1988, production production began on its left bank using the flowing method from well No. 181-R with a flow rate of 37 tons per day. On the last day of July 2006, Priobsky oil workers reported the production of the 100 millionth ton of oil.

The license for the development of the field belongs to OJSC Yuganskneftegaz.
The largest field in Western Siberia - Priobskoye - is administratively located in the Khanty-Mansiysk region at a distance of 65 km from Khanty-Mansiysk and 200 km from Nefteyugansk. Priobskoye was discovered in 1982. It is divided by the Ob River into two parts - the left and right banks. Development of the left bank began in 1988, the right - in 1999.

According to the Russian classification, proven oil reserves amount to 1.5 billion tons, recoverable reserves amount to more than 600 million.
According to the analysis prepared by the international auditing company DeGolyer & MacNaughton, as of December 31, 2005, the oil reserves of the Priobskoye field according to the SPE methodology are: proven 694 million tons, probable - 337 million tons, possible - 55 million tons.

Reserves for the field according to Russian standards as of January 1, 2006: NGZ (Oil and Gas Reserves) - 2476.258 million tons.

Oil production at the Priobskoye field in 2003 amounted to 17.6 million tons, in 2004 - 20.42 million tons, in 2005 - 20.59 million tons. In the company's strategic development plans, the Priobskoye deposit is given one of the main places - by 2009 it is planned to produce up to 35 million tons here.
On the last day of July 2006, Priobsky oil workers reported the production of the 100 millionth ton of oil. 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.

History of the Priobskoye field:
In 1985, industrial oil reserves were discovered; testing of well 181r resulted in an influx of 58 m3/day
In 1989, drilling of 101 clusters began (Left Bank)
In 1999 - commissioning of wells in 201 clusters (Right Bank)
In 2005, daily production amounted to 60,200 tons/day, the production stock of 872 wells, 87,205.81 thousand tons produced since the beginning of development.

In recent years alone, using directional drilling, 29 underwater crossings have been completed in the field, including 19 new ones built and 10 old ones reconstructed.

Site facilities:
Booster pumping stations - 3
Multiphase pumping station Sulzer - 1
Cluster pumping stations for pumping working agent into the formation - 10
Floating pumping stations - 4
Oil preparation and pumping workshops - 2
Oil separation unit (OSN) - 1

In May 2001, a unique Sulzer multiphase pumping station was installed at the 201st cluster 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 Rosskor pumping station was installed at the Priobskoye field in 2000. It is designed for in-field pumping of multiphase liquid without the use of flares (to avoid flaring of associated gas in the floodplain part of the Ob River).

The drill cuttings processing plant on the right bank of the Priobskoye field produces sand-lime brick, which is used as a building material for the construction of roads, well pads, etc. To solve the problem of utilization of associated gas produced at the Priobskoye field, the first gas turbine power plant in the Khanty-Mansi Autonomous Okrug was built at the Prirazlomnoye field, providing electricity to the Priobskoye and Prirazlomnoye fields.

The power transmission line built across the Ob River has no analogues; its span is 1020 m, and the diameter of the wire, specially manufactured in the UK, is 50 mm.
http://vestnik.rosneft.ru/47/article4.html

November 5, 2009 became another significant day in the history of Yuganskneftegaz - the 200 millionth ton of oil was produced at the Priobskoye field. Let us remember that this giant oil field was discovered in 1982. The field is located near Khanty-Mansiysk and is divided into two parts by the Ob River. Development of the left bank began in 1988, the right - in 1999. The 100 millionth ton of oil was produced at the field in July 2006.
http://www.uralpolit.ru/86/econom/tek/id_160828.html

03/24/2010 NK Rosneft plans to produce 29.6 million tons of oil at the Priobskoye field in 2010, which is 12.4% less than what was produced in 2009, according to a statement from the company’s information department. In 2009, Rosneft produced 33.8 million tons of oil from the field.

In addition, according to the message, today Rosneft commissioned the first stage of a gas turbine power plant (GTPP) at the Priobskoye oil and gas field. The capacity of the first stage of the GTPP is 135 MW, the second stage is planned to be commissioned in May 2010, the third - in December. The total capacity of the station will be 315 MW. Construction of the station along with auxiliary facilities will cost Rosneft 18.7 billion rubles. At the same time, according to the report, due to the abandonment of hydraulic structures and the installation of steam power equipment, capital costs for the construction of gas turbine power plants were reduced by more than 5 billion rubles.

The head of Rosneft, Sergei Bogdanchikov, noted that the commissioning of the Priobskaya GTPP solves three problems simultaneously: utilization of associated gas (APG), providing electricity to the field, as well as the stability of the region’s energy system.

In 2009, Rosneft produced more than 2 billion cubic meters from the Priobskoye field. m of associated petroleum gas (APG), but used only a little more than 1 billion cubic meters. m. By 2013, the picture will change: despite the reduction in APG production to 1.5 billion cubic meters. m, its use will reach 95%, the report notes.

According to S. Bogdanchikov, Rosneft is considering the possibility of providing Gazprom Neft with its pipe for transporting associated petroleum gas from the Priobskoye field for utilization at the Yuzhno-Balyksky gas processing complex of the SIBUR company. RBC reports this.
http://www.oilcapital.ru/news/2010/03/241042_151839.shtml

Rosneft provides up to 30% of its energy consumption with its own facilities. Power plants operating on associated gas have been built: at the Priobskoye field, at Vankor, in the Krasnodar Territory.
http://museum.rosneft.ru/future/chrono/year/2020/

19/12/2009
Gazprom Neft has launched the first stage of the Yuzhno-Priobskaya gas turbine power plant (GTPP) at the Priobskoye field (KhMAO), built by the company for its own production needs, the company said in a statement.
The capacity of the first stage of the gas turbine power plant was 48 MW. The volume of capital investments for the introduction of the first stage is 2.4 billion rubles.
Currently, Gazpromneft-Khantos' electricity needs amount to about 75 MW of electricity and, according to calculations by company specialists, by 2011 energy consumption will increase to 95 MW. In addition, in the coming years, the tariffs of the Tyumen energy system will increase significantly - from 1.59 rubles per kWh in 2009 to 2.29 rubles per kWh in 2011.
The launch of the second stage of the power plant will increase the energy generating capacity of Gazpromneft-Khantos to 96 MW and will fully satisfy the enterprise's electricity needs.

The Priobskoye field is a key asset of Gazprom Neft, occupying almost 18% of the company’s production structure.
http://www.rian.ru/economy/20091219/200247288.html
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Disaggregation of development objects as a method for increasing oil recovery
At the Priobskoye field, three formations are being developed jointly - AC10, AS11, AS12, and the permeability of the AC11 formation is an order of magnitude higher than the permeability of the AC10 and AS12 formations. To effectively develop reserves from low-permeability AC10 and AC12 formations, there is no other alternative than the introduction of ORRNEO technology, primarily at injection wells.
http://www.neftegaz.ru/science/view/428

Methodology for integrated interpretation of well logging results used at OJSC ZSK TYUMENPROMGEOFIZIKA when studying terrigenous sections
http://www.tpg.ru/main.php?eng=&id=101&pid=85

Frolovskaya facies zone of the Neocomian of Western Siberia in the light of assessing the prospects for oil and gas potential
http://www.neftegaz.ru/science/view/486
http://www.oilnews.ru/magazine/2005-15-09.html
Literature

Regional stratigraphic schemes of Mesozoic deposits of the West Siberian Plain. - Tyumen. - 1991.
Geology of oil and gas in Western Siberia // A.E. Kontorovich, I.I. Nesterov, V.S. Surkov et al. - M.: Nedra. - 1975. - 680 p.
Catalog of stratigraphic breakdowns // Tr. ZapSibNIGNI.-1972.- Issue. 67.-313 p.
Argentovsky L.Yu., Bochkarev V.S. and others. Stratigraphy of Mesozoic deposits of the platform cover of the West Siberian plate // Problems of geology of the West Siberian oil and gas province / Tr. ZapSibNIGNI.- 1968.- Issue 11.- 60 p.
Sokolovsky A.P., Sokolovsky R.A. Anomalous types of sections of the Bazhenov and Tutleim formations of Western Siberia // Bulletin of the subsoil user of the Khanty-Mansi Autonomous Okrug. - 2002.-11.- P. 64-69.

Efficiency of oil field development
In Russia, both horizontal wells and hydraulic fracturing are used in sufficient quantities in low-permeability reservoirs, for example, in the Priobskoye field, where the permeability is only from 1 to 12 millidarcy and hydraulic fracturing is simply not possible.
http://energyland.info/analitic-show-neft_gaz-neftegaz-52660

A new environmental scandal in the Khanty-Mansiysk Autonomous Okrug. Once again, its participant was the well-known company Rosekoprompererabotka, which became famous for polluting the Vakh River in the domain of TNK-BP.
http://www.ura.ru/content/khanti/15-07-2010/articles/1036255339.html

Improving the quality of cementing casing strings at the Yuzhno-Priobskoye field
http://www.burneft.ru/archive/issues/2009-12/6

Thermal gas impact and deposits of Siberia
http://www.energyland.info/analitic-show-52541
Thermal gas method and the Bazhenov formation
http://energyland.info/analitic-show-50375

Introduction of simultaneous separate injection at the Priobskoye field
http://www.oil-info.ru/arxivps/pdf/ORZ_N.pdf
Conversion of Priobskoe field wells to an adaptive electric centrifugal pump control system
http://www.elekton.ru/pdf/adaptive%20exploitation.pdf

Analysis of ESP failures at Russian fields
http://neftya.ru/?p=275

Interruptions during the formation of Neocomian clinoforms in Western Siberia
http://geolib.narod.ru/Journals/OilGasGeo/1993/06/Stat/01/stat01.html

Improving the technology of simultaneous-separate injection for multi-layer fields
http://www.rogtecmagazine.com/rus/2009/09/blog-post_1963.html

LLC "Mamontovsky KRS"
Work at the fields of Mamontovsky, Maysky, Pravdinsky, Priobsky regions
http://www.mkrs.ru/geography.aspx

28.01.2010
Even before the New Year, environmental inspections were completed at the two largest fields in Ugra, Samotlor and Priobskoye. Based on the results, disappointing conclusions were drawn: oil workers not only destroy nature, but also underpay at least 30 billion rubles a year to budgets at various levels.
http://www.t-i.ru/article/13708/

"Siberian Oil", No. 4(32), April 2006. "There is room to move"
http://www.gazprom-neft.ru/press-center/lib/?id=685

BP/AMOCO Withdraws from Priobskoye Project, 1999-03-28
http://www.russiajournal.com/node/1250

Photo
Priobskoye field
http://www.amtspb.ru/map.php?objectID=15
"Priobskoye field, Khanty-Mansi Autonomous Okrug. SGK-Burenie company."
http://nefteyugansk.moifoto.ru/112353
Yuzhno-Priobskoye field

They are located in Saudi Arabia, even a high school student knows. Just like the fact that Russia is right behind it in the list of countries with significant oil reserves. However, in terms of production level we are inferior to several countries.

There are the largest ones in Russia in almost all regions: in the Caucasus, in the Ural and West Siberian districts, in the North, in Tatarstan. However, not all of them have been developed, and some, such as Techneftinvest, 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 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 carried out by several companies 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 on both the left and right banks. 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 contains over 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 a Priobskaya gas turbine power plant near the field, operating exclusively on associated fuel. This station not only fully meets the demands of the field. It is capable of supplying produced electricity to the Khanty-Mansiysk Okrug for the needs of residents.

Today, several companies are developing the Priobskoye field.

Some believe that during production, finished, purified oil comes out of the ground. This is a deep misconception. Reservoir fluid that comes out to

the surface (crude oil) enters the workshops, where it is cleaned of impurities and water, the amount of magnesium ions is normalized, and associated gas is separated. This is a large and highly precise job. To carry it out, 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 the biggest problem for the field today: so many of them have accumulated that it is not yet possible to eliminate them.

The enterprise, created specifically for recycling, today processes only the “freshest” waste. Expanded clay, which is in great demand in construction, is made from sludge (as they call it at the enterprise). However, so far only access roads for the deposit are built from the resulting expanded clay.

The deposit has another significance: it provides stable, well-paid work for several thousand workers, among whom there are highly qualified specialists and unskilled workers.

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Introduction

1 Geological characteristics of the Priobskoye field

1.1 General information about the field

1.2 Lithostratigraphic section

1.3 Tectonic structure

1.4 Oil content

1.5 Characteristics of productive formations

1.6 Characteristics of aquifer complexes

1.7 Physico-chemical properties of 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 development of the Priobskoye field

2.2 Analysis of the main technical and economic indicators of development

2.3 Development features affecting well operation

3. Applied methods for enhancing oil recovery

3.1 Selecting a method of influencing an oil deposit

3.2 Geological and physical criteria for the applicability of various impact methods in the Priobskoye field

3.2.1 Reservoir flooding

3.3 Methods of influencing the bottomhole zone of a well to intensify 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 influencing 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 pressing problem today. Oil resources are gradually being 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 primary task is the search and commissioning of young and promising fields, one of which is the Priobskoye field (in terms of reserves, it is one of largest deposits in Russia).

Balance oil reserves approved by the State Reserves Committee for category C 1 are 1827.8 million tons, recoverable reserves are 565.0 million tons. with an oil recovery factor of 0.309, taking into account reserves in the protective zone under the floodplains of the Ob and Bolshoy Salym rivers.

The balance oil reserves of category C 2 are 524,073 thousand tons, recoverable reserves are 48,970 thousand tons with an oil recovery factor of 0.093.

The Priobskoye field has a number of characteristic features:

large, multi-layer, 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 territory of the deposit, dividing it into right-bank and left-bank parts.

The field is characterized by a complex structure of productive horizons. The AS10, AS11, and AS12 formations are of industrial interest. The reservoirs of horizons AC10 and AC11 are classified as medium and low productive, and AC12 are classified as abnormally low productive. The exploitation of the AC12 formation should be identified as a separate development problem, because , the AC12 formation is also the most significant in terms of reserves of all formations. This characteristic indicates the impossibility of developing the field without actively influencing its productive strata.

One of the ways to solve this problem is to implement measures to intensify oil production.

1 . Geological characteristicsPriobskydeposits

1.1 General information about the field

The Priobskoye oil field is administratively located in the Khanty-Mansiysk region of the Khanty-Mansiysk Autonomous Okrug of the Tyumen Region.

The work area is located 65 km east of the city of Khanty-Mansiysk, 100 km west of the city of Nefteyugansk. Currently, the area is one of the most economically developing in the Autonomous Okrug, which became possible due to the increase 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 close proximity, Pravdinskoye - 57 km to the southeast.

To the southeast of the field are the routes of the Urengoy - Chelyabinsk - Novopolotsk gas pipeline and the Ust-Balyk-Omsk oil pipeline.

The northern part of the Priobskaya area is located within the Ob floodplain - a young alluvial plain with the accumulation of Quaternary sediments of relatively large thickness. The absolute elevations of the relief are 30-55 m. The southern part of the area gravitates towards a flat alluvial plain at the level of the second terrace above the floodplain with weakly expressed forms of river erosion and accumulation. The absolute elevations 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 of Malaya Berezovskaya and Pola with the large and full-flowing Ob channel of Bolshoy Salym. The Ob River is the main waterway of the Tyumen region. There are a large number of lakes in the region, the largest of which are Lake Olevashkina, Lake Karasye, Lake Okunevoe. The swamps are impassable, freeze by the end of January and are the main obstacle to vehicle movement.

The climate of the area 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 -19.5 degrees C). The absolute minimum is -52 degrees C. The warmest month is July (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% occurring in the warm season. Snow cover is established in the second half of October and continues until the beginning of 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 region 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 mainly sandy, and in some places clayey. The flora is diverse. Coniferous and mixed forests predominate.

The area is located in a zone of isolated occurrence of near-surface and relict permafrost rocks. Near-surface frozen soils occur on watersheds under peatlands. Their thickness is controlled by the groundwater level and reaches 10-15 m, the temperature is constant and close to 0 degrees C.

In the adjacent territories (permafrost has 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. The lower, more clayey part of the Novomikhailovskaya and a small part of the Atlym formations are often frozen.

The largest settlements closest to the work area are the cities of Khanty-Mansiysk, Nefteyugansk, Surgut and smaller settlements - the villages of Seliyarovo, Sytomino, Lempino and others.

1.2 Lithostratigraphiccut

The geological section of the Priobskoye field is composed of a thick layer (more than 3000 m) of terrigenous deposits of the sedimentary cover of Mesozoic-Cenozoic age, overlying rocks of the pre-Jurassic complex, represented by weathering crust.

Pre-Jurassic education (Pz)

In the section of the pre-Jurassic strata, two structural floors are distinguished. The lower one, confined to the consolidated crust, is represented by highly dislocated graphite-porphyrites, gravelites and metamorphosed limestones. The upper floor, identified as an intermediate complex, consists of less dislocated effusive-sedimentary deposits of Permian-Triassic age up to 650 m thick.

Jurassic system (J)

The Jurassic system is represented by all three divisions: lower, middle and upper.

Its composition includes the Tyumen (J1+2), Abalak and Bazhenov formations (J3).

Sediments Tyumen the formations lie at the base of the sedimentary cover on 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 Tyumen formation sediments varies from 40 to 450 m. Within the field they were discovered at depths of 2806-2973 m. The deposits of the Tyumen formation are conformably overlain by the Upper Jurassic deposits of the Abalak and Bazhenov formations. Abalakskaya The formation is composed of dark gray to black, locally calcareous, glauconitic mudstones with siltstone interlayers in the upper part of the section. The thickness of the formation ranges from 17 to 32 m.

Sediments Bazhenovskaya The formations are represented by dark gray, almost black, bituminous mudstones with interlayers of weakly silty mudstones and organogenic clayey carbonate rocks. The thickness of the formation 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.

In the lower section, from bottom to top, the Akhskaya, Cherkashinskaya, Alymskaya, Vikulovskaya and Khanty-Mansiysk formations are distinguished, and in the upper section, the Khanty-Mansiysk, Uvatskaya, Kuznetsovskaya, Berezovskaya and Gankinskaya formations.

Bottom part awesome Formation (K1g) is represented mainly by mudstones with subordinate thin interlayers of siltstones and sandstones, combined into the Achimov sequence.

In the upper part of the Akh Formation, a mature member of finely pulverized, dark gray, approaching gray Pim clays is distinguished.

The total thickness of the formation varies from west to east from 35 to 415 m. In sections located to the east, a group of layers BS1-BS12 are confined to this strata.

Cut Cherkashinskaya formation (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 are distinguished in the formations AC7, AC9, AC10, AC11, AC12.

The thickness of the formation varies from 290 to 600 m.

Above are dark gray to black clays Alymskaya formation (K1a), in the upper part with interlayers of bituminous mudstones, in the lower part - siltstones and sandstones. The thickness of the formation varies from 190 to 240 m. Clays are the regional seal for hydrocarbon deposits throughout the Middle Ob oil and gas region.

Vikulovskaya Formation (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 formation ranges from 264 m in the west to 296 m in the northeast.

Khanty-Mansiysk Formation (K1a-2s) is represented by uneven interbedding of sandy-clayey rocks with a predominance of the former in the upper part of the section. The rocks of the formation are characterized by an abundance of carbonaceous detritus. The thickness of the formation varies from 292 to 306 m.

Uvatskaya Formation (K2s) is represented by uneven alternation 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 Formation (K2k-st-km) is divided into two subformations. The lower one, consisting of gray montmorellonite clays, opoka-like interlayers with a thickness of 45 to 94 m, and the upper one, represented by gray, dark gray, siliceous, sandy clays, 87-133 m thick.

Gankinskaya Formation (K2mP1d) consists of gray, greenish-gray clays turning into marls with glauconite grains and siderite nodules. Its thickness is 55-82m.

Paleogene system (P2)

The Paleogene system includes rocks of the Talitsky, Lyulinvor, Atlym, Novomikhailovsky and Turtas formations. The first three are represented by marine deposits, the rest - continental.

Talitskaya The formation is composed of thick dark gray clays and silty areas. Peritized plant remains and fish scales are found. The thickness of the formation is 125-146 m.

Lyulinvorskaya The formation is represented by yellowish-green clays, in the lower part of the section they are often opokoid with opokoid interlayers. The thickness of the formation is 200-363 m.

Tavdinskaya The formation that completes the marine Paleogene section is made of gray, bluish-gray clays with interlayers of siltstone. The thickness of the formation is 160-180 m.

Atlymskaya The formation is composed of continental alluvial-marine sediments, consisting of sands, gray to white, predominantly quartz with interlayers of brown coal, clays and siltstones. The thickness of the formation is 50-60 m.

Novomikhailovskaya formation - represented by uneven interlayering of sands, gray, fine-grained, quartz-feldspathic with clays and gray and brownish-gray siltstones with interlayers of sand and brown coals. The thickness of the formation does not exceed 80 m.

Turtasskaya The formation consists of clays and greenish-gray siltstones, thin-layered with interlayers of diatomites and quartz-glauconite sands. The thickness of the formation is 40-70 m.

Quaternary system (Q)

It is present everywhere and is represented in the lower part by alternating sands, clays, loams and sandy loams, in the upper part by swamp and lake facies - silts, loams and sandy loams. The total thickness is 70-100 m.

1.3 Tectonicstructure

The Priob structure is located in the junction zone of the Khanty-Mansi depression, the Lyaminsky megatrough, the Salym and West Lempinsky groups of uplifts. The first-order structures are complicated by swell-shaped and dome-shaped uplifts of the second order and individual local anticlinal structures, which are objects of prospecting and exploration work for oil and gas.

The modern structural plan of the pre-Jurassic foundation has been studied using 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 there are the Seliyarovskoye, West Sakhalin, and Svetloye uplifts. In the northwestern part there are East Seliyarovskoye, Krestovoe, Zapadno-Gorshkovskoye, Yuzhno-Gorshkovskoye, complicating the eastern slope of the West Lempinsky uplift zone. In the central part there is the Western Sakhalin trough, to the east of it the Gorshkovsky and Sakhalin uplifts, complicating the Middle Lyaminsky swell and the Sakhalin structural nose, respectively.

Along the reflecting horizon “Db”, confined to the roof of the Bystrinskaya member, the Priobskoye dome-shaped uplift, the West Priobskoye low-amplitude uplift, the West Sakhalin, Novoobskaya structures can be traced. In the west of the area the Khanty-Maniya uplift is outlined. To the north of the Priobsky uplift, the Svetloye 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 outlined by an open seismic isohypse - 2280 m. Near well 606 a low-amplitude isometric structure can be traced. The Seliyarovskaya area is covered by a rare network of seismic profiles, on the basis of which a positive structure can be conditionally predicted. The Seliyarovsky uplift is confirmed by a 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, conditionally, a dome-shaped nameless uplift is identified.

1.4 Oil content

At the Priobskoye field, the oil-bearing level covers significant thicknesses of sedimentary cover from the Middle Jurassic to the Aptian age and is more than 2.5 km.

Non-industrial oil inflows and cores with signs of hydrocarbons were obtained from 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 is currently not sufficiently substantiated.

Commercial oil content has been established in the Neocomian formations of the AS group, where 90% of proven reserves are concentrated. The main productive strata are located between the Pimskaya and Bystrinskaya clay packs. The deposits are confined to lens-shaped sand bodies formed in Neocomian shelf and clinoform deposits, the productivity of which is not controlled by the modern structural plan and is determined almost exclusively 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 units are closed lens-shaped bodies completely filled with oil, and the contours of the deposits for each sand layer are determined by the boundaries of its distribution. The exception is the AS 7 formation, where inflows of formation water were obtained from sand lenses filled with water.

As part of the productive Neocomian deposits, 9 counting 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. The deposits of the AC 7 and AC 9 layers are not of industrial interest.

The geological profile is presented in Fig. 1.1

1.5 Characteristicsproductivelayers

The main oil reserves in 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 clastic terrigenous material from the east and southeast. The formation of the Neocomian megacomplex of sedimentary rocks occurred in a whole series of paleogeographic conditions: continental sedimentation, coastal-marine, shelf and very slow deposition of sediments in the open deep sea.

As you move from east to west, there is a tilt (in relation to the Bazhenov formation, which is a regional benchmark) of both clayey mature members (zonal benchmark) and the sandy-siltstone rocks contained between them.

According to the determinations made by ZapSibNIGNI specialists 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 Pima Member. They are indexed as an AS group, therefore, at the Priobskoye field, formations BS 1-5 were re-indexed to AS 7-12.

When calculating reserves within the megacomplex of productive Neocomian deposits, 11 productive formations were identified: AS12/3, AS12/1-2, AS12/0, AS11/2-4, AS11/1, AS11/0, AS10/2-3, AS10/ 1, AC10/0, AC9, AC7.

The AS 12 reservoir unit lies at the base of the megacomplex and is the most deep-water part from the point of view of formation. The composition includes three layers AS 12/3, AS 12/1-2, AS 12/0, which are separated from each other by relatively consistent clays over most of the area, the thickness of which ranges from 4 to 10 m.

The deposits of the AS 12/3 formation are confined to a monoclinal element (structural nose), within which there are low-amplitude uplifts and depressions with transition zones between them.

The main deposit AS12/3 was discovered at depths of 2620-2755 m and is lithologically screened on all sides. In terms of area, it occupies the central terrace-like, most elevated part of the structural nose and is oriented from southwest to northeast. Oil-saturated thicknesses vary from 12.8 m to 1.4 m. Oil flow rates range from 1.02 m 3 /day, Hd=1239m to 7.5 m 3 /day with Hd=1327m. The dimensions of the lithologically screened deposit are 25.5 km by 7.5 km, height 126 m.

The AS 12/3 deposit was discovered at depths of 2640-2707 m and is confined to the Khanty-Mansi local uplift and the zone of its eastern subsidence. The deposit is controlled from all sides by reservoir replacement zones. Oil flow rates are low and amount to 0.4-8.5 m 3 /day at various dynamic levels. The highest elevation in the arched part is recorded at -2640 m, and the lowest at (-2716 m). The deposit dimensions are 18 by 8.5 km, height 76 m. Lithologically screened type.

The main deposit AS12/1-2 is the largest in the field. It was discovered 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 (towards the East 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 thickness (more than 12 m) covers the central part of the reservoir, as well as the eastern part. The dimensions of the lithologically screened deposit are 45 km by 25 km, height 176 m.

In the AS 12/1-2 formation, deposits of 7.5 by 7 km, 7 m high, and 11 by 4.5 km, 9 m high, were discovered. Both deposits are of lithologically screened type.

The AS 12/0 formation has a smaller development zone. The main deposit AS 12/0 is a lens-shaped body oriented from southwest to northeast. Its dimensions are 41 by 14 km, height 187 m. Oil flow rates vary from the first units of m 3 / day at dynamic levels up to 48 m 3 / day.

The cap of the AC 12 horizon is formed by a thick (up to 60 m) layer of clayey rocks.

Higher up the section lies the AS 11 pack of productive strata, which includes AS 11/0, AS 11/1, AS 11/2, AS 11/3, AS 11/4. The last three are connected into a single counting object, which has a very complex structure both in section and in area. In the reservoir development zones, which gravitate toward near-crest 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 layer, in the central part - by the AS 11/3 layer, in the north - by the AC 11/2-4 layer.

The main deposit AS11/1 is the second largest within the Priobskoye field. The AS11/1 formation is developed in the near-crest part of a swell-like uplift of submeridional strike, complicating the monocline. On three sides the deposit is limited by clay zones, and in the south the border is drawn conditionally. The dimensions of the main deposit are 48 by 15 km, height 112 m. Oil flow rates vary from 2.46 m 3 /day at a dynamic level of 1195 m to 11.8 m 3 /day.

The AS 11/0 formation was identified in the form of isolated lens-shaped 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 of lithologically screened type. They are characterized by oil inflows from 4 to 14 m 3 /day at a dynamic level. The AC 10 horizon was penetrated by almost all wells and consists of three layers AC 10/2-3, AC 10/1, AC 10/0.

The main deposit AS 10/2-3 was discovered at depths of 2427-2721 m and is located in the southern part of the field. Type of deposit - lithologically screened, dimensions 31 by 11 km, height up to 292 m. 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 dimensions of the deposit are 38 by 13 km, height up to 120 m. The southern boundary is drawn tentatively. Oil-saturated thicknesses vary 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 6.4 m 3 /day.

The section of the AS 10 formation is completed by the AS 10/0 productive formation, within which three deposits were identified, located in the form of a chain of submeridial strike.

Horizon AC 9 has a limited distribution and is presented in the form of separate fascial zones located in the northeastern and eastern sections of the structure, as well as in the area of ​​the southwestern plunge.

The Neocomian productive deposits are completed by the AS 7 formation, which has a mosaic pattern in the distribution of oil-bearing and aquifer fields.

The largest in area, the Eastern deposit, was discovered at depths of 2291-2382 m. It is oriented from southwest to northeast. Oil inflows are 4.9-6.7 m 3 /day at dynamic levels of 1359-875 m. Oil-saturated thicknesses vary from 0.8 to 67.8 m. The dimensions of the deposit are 46 by 8.5 km, height 91 m.

A total of 42 deposits have been discovered within the field. The maximum area is the main deposit in the AS 12/1-2 formation (1018 km 2), the minimum (10 km 2) is the deposit in the AC 10/1 formation.

Summary table of parameters of productive formations within the production area

Table 1.1

geological production deposit oil bearing formation

1.6 Characteristicsaquiferscomplexes

The Priobskoye field is part of the hydrodynamic system of the West Siberian artesian basin. Its peculiarity is the presence of waterproof clayey deposits of the Oligocene-Turonian, the thickness of which reaches 750 m, dividing the Mesozoic-Cenozoic section into upper and lower hydrogeological levels.

The upper floor combines sediments of Turonian-Quaternary age and is characterized by free water exchange. In hydrodynamic terms, a floor is an aquifer whose groundwater and interstratal waters are interconnected.

The upper hydrogeological stage includes three aquifers:

1- aquifer of Quaternary sediments;

2- aquifer of Novomikhailovsky deposits;

3- aquifer of Atlym sediments.

A comparative analysis of aquifers showed that the Atlym aquifer can be accepted as the main source of 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 level is represented by sediments of the Cenomanian-Jurassic age and watered rocks of the upper part of the pre-Jurassic basement. At great depths, in an environment of difficult, and in some places almost stagnant, thermal highly mineralized waters are formed, having 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. In its section there are four aquifer complexes. All complexes and aquitards can be traced over a considerable distance, but at the same time, at the Priobskoye field, clayization of the second complex is observed.

For flooding of oil reservoirs in the Middle Ob region, underground waters of the Aptian-Cenomanian complex are widely used, composed of a layer of weakly cemented, loose sands, sandstones, siltstones and clays of the Uvat, Khanty-Mansi and Vikulov formations, well-consistent in area and fairly homogeneous within the area. The waters are characterized by low corrosive ability due to the absence of hydrogen sulfide and oxygen in them.

1.7 Physico-chemicalpropertiesreservoirfluids

Reservoir oils from productive formations AC10, AC11 and AC12 do not have significant differences in their properties. The nature of the change in the physical properties of oils is typical for deposits that do not reach the surface and are surrounded by marginal water. In reservoir conditions of oil of average gas saturation, the saturation pressure is 1.5-2 times lower than reservoir pressure (high degree of compression).

Experimental data on the variability of oils across the section of the field's production facilities indicate insignificant heterogeneity of oil within the deposits.

The oils of the AS10, AS11, and AS12 formations are close to each other, the lighter oil is in the AS11 formation, the molar fraction of methane in it is 24.56%, the total content of hydrocarbons C2H6 -C5H12 is 19.85%. Oils from all layers are characterized by a predominance of normal butane and pentane over isomers.

The amount of light hydrocarbons CH4 - C5H12 dissolved in degassed oils is 8.2-9.2%.

Oil gas of standard separation is high-fat (fat content coefficient more than 50), the molar fraction of methane in it is 56.19 (AS10 formation) - 64.29 (AS12 formation). The amount of ethane is much less than propane, the C2H6 / C3H8 ratio is 0.6, which is typical for gases from oil deposits. The total content of butanes is 8.1-9.6%, pentanes 2.7-3.2%, heavy hydrocarbons C6H14 + higher 0.95-1.28%. The amount of carbon dioxide and nitrogen is small, about 1%.

Degassed oils of all layers are sulphurous, paraffinic, low-resin, and of medium density.

The oil of the AS10 formation is of medium viscosity, with a content of fractions up to 350_C greater than 55%, the oils of the AS11 and AS12 formations are viscous, with a content of fractions up to 350_C from 45% to 54.9%.

Technological code of oils from formation AS10 - II T1P2, formations AS11 and AS12 - II T2P2.

The assessment of parameters determined by the individual characteristics of oils and gases was carried out in accordance with the most likely conditions for the collection, preparation and transportation of oil in the field.

The separation conditions are as follows:

1st stage - pressure 0.785 MPa, temperature 10_C;

Stage 2 - pressure 0.687 MPa, temperature 30_C;

Stage 3 - pressure 0.491 MPa, temperature 40_C;

Stage 4 - pressure 0.103 MPa, temperature 40_C.

Comparison of average porosity and permeability values ​​of reservoirsAS10-AS12 layers based on core and GIS

Table 1.2

1.8 Estimation of oil reserves

The assessment of oil reserves of the Priobskoye field was carried out as a whole for reservoirs without differentiation by deposits. Due to the lack of formation water in lithologically limited deposits, reserves were calculated based on purely oil zones.

The balance oil reserves of the Priobskoye field were estimated using the volumetric method.

The basis for calculating reservoir models was the results of GIS interpretation. At the same time, the following estimates of reservoir parameters were taken as reservoir-non-reservoir boundary values: K op 0.145, permeability 0.4 mD. Zones of formations in which the values ​​of these parameters were less than standard were excluded from reservoirs and, therefore, reserve calculations.

When calculating reserves, the method of multiplying maps of three main calculation parameters was used: effective oil-saturated thickness, open porosity coefficients and oil saturation. Effective oil-saturated volume was calculated separately for reserve categories.

The allocation of categories of reserves was carried out in accordance with the “Classification of deposit reserves...” (1983). Depending on the level of exploration of the deposits of the Priobskoye field, the reserves of oil and dissolved gas in them are calculated according to categories B, C 1, C 2. Category B reserves are identified within the last wells of the production series on the left bank drilled section of the field. Category C 1 reserves were identified in areas studied by exploration wells in which commercial oil flows were obtained or positive logging information was available. Reserves in areas of deposits that have not been studied by drilling were classified into category C 2. The boundary between categories C 1 and C 2 was drawn at a distance of double spacing of the operational grid (500x500 m), as provided for by the “Classification...”.

The reserve assessment was completed by multiplying the obtained volumes of oil-saturated reservoirs for each layer and within the selected categories by the density of oil degassed during stepwise separation and the conversion factor. It should be noted that they are somewhat different from those previously adopted. This is due, firstly, to the exclusion from the calculations of wells located far beyond the license area, and, secondly, to changes in the indexation of formations in individual exploration wells as a result of a new correlation of productive deposits.

The accepted calculation parameters and the obtained results of calculating oil reserves are given below.

1.8.1 Reservesoil

As of January 1, 1998, oil reserves on the VGF balance sheet are listed as follows:

Recoverable 613,380 thousand tons.

Recoverable 63,718 thousand tons.

Recoverable 677,098 thousand tons.

Oil reserves by reservoir

Table 1.3

For the drilled section of the left bank part of the Priobskoye field, the Party of Yuganskneftegaz JSC reserves calculation was carried out.

The drilled part contains 109,438 thousand tons. balance and 31131 thousand tons. recoverable oil reserves with an oil recovery factor of 0.284.

According to the drilled part, the reserves are distributed by seam as follows:

Formation AS10 balance 50%

Recoverable 46%

Formation AS11 balance 15%

Recoverable 21%

Formation AS12 balance 35%

Recoverable 33%

In the territory under consideration, the main volume of reserves is concentrated in the AC10 and AC12 formations. This area contains 5.5% of oil reserves. 19.5% of AS10 reservoir reserves; 2.4%-AC11; 3.9%-AC12.

Priobskoem/r (left bankPart)

ReservesoilByzoneoperation

Table 1.4

*) For part of the territory of category C1 from which oil is produced

2 . Extraction methods, equipment used

The development of each production facility AS 10, AS 11, AS 12 was carried out by placing wells according to a linear three-row triangular pattern with a grid density of 25 hectares/well, with all wells drilled to the AS 12 formation.

In 2007, SibNIINP prepared an “Addendum to the technological scheme for the pilot industrial development of the left-bank part of the Priobskoye field, including the floodplain section N4,” which included adjustments for the development of the left-bank part of the field with the inclusion of new clusters N140 and 141 in the floodplain part of the field . In accordance with this document, it is envisaged to implement a three-row block system (grid density - 25 hectares/sq.m.) with a subsequent transition to a closed block system at a later stage of development.

The dynamics of the main technical and economic indicators of development are presented in Table 2.1

2. 1 DynamicsmainindicatorsdevelopmentPriobskydeposits

table 2.1

2. 2 Analysismaintechnical and economicindicatorsdevelopment

The dynamics of development indicators based on Table 2.1 are presented in Fig. 2.1.

The Priobskoye field has been developed since 1988. Over 12 years of development, as can be seen from Table 3, oil production has been constantly growing.

If in 1988 it amounted to 2,300 tons of oil, then by 2010 it reached 1,485,000 tons, liquid production increased from 2,300 to 1,608,000 tons.

Thus, by 2010, accumulated 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 stock was 132 wells, and water injection increased from 100 to 2362 thousand tons. by 2010. As injection increases, the average oil production rate of operating wells increases. By 2010, the flow rate increases, which is explained by the correct choice of the amount of injected water.

Also, from the moment the injection fund is put into operation, the water cut of the product begins to increase 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 were wells extracting products using mechanized methods. By 2010, the accumulated 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,influencingonexploitationwells

The field is characterized by low well flow rates. The main problems of field development were the low productivity of production wells, low natural (without fracturing formations with injected water) injectivity of injection wells, as well as poor redistribution of pressure across the deposits during reservoir pressure maintenance (due to weak hydrodynamic connection of individual sections of the formations). The exploitation of the AC 12 formation should be highlighted as a separate problem of field development. Due to low flow rates, many wells in this formation must be shut down, which could lead to significant oil reserves being mothballed indefinitely. One of the ways to solve this problem in the AS 12 reservoir is to implement measures to intensify oil production.

The Priobskoye field is characterized by a complex structure of productive horizons both in area and in section. The reservoirs of horizons AS 10 and AS 11 are classified as medium and low productive, and AS 12 are classified as abnormally low productive.

The geological and physical characteristics of the productive strata of the field indicate the impossibility of developing the field without active influence on its productive strata and without the use of production intensification methods.

This is confirmed by the experience of developing the operational section of the left bank part.

3 . Applied methods for enhancing oil recovery

3.1 Choicemethodimpactonoildeposit

The choice of a method of 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 capabilities of implementing the method in a given field and economic criteria. The methods of influencing the formation listed above have numerous modifications and are fundamentally 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.

Among the methods of intensifying oil production by influencing the bottom-hole zone of a well, the most widely used are:

hydraulic fracturing;

acid treatments;

physical and chemical treatments with various reagents;

thermophysical and thermo-chemical treatments;

pulse-shock, vibroacoustic and acoustic effects.

3.2 Geological and physical criteria for the applicability of various impact methods at 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 formations - 2400-2600 m,

deposits are lithologically screened, natural regime is elastic closed,

the thickness of the AS 10, AS 11 and AS 12 layers is up to 20.6, 42.6 and 40.6 m, respectively.

initial reservoir pressure - 23.5-25 MPa,

reservoir temperature - 88-90 0 C,

low permeability of reservoirs, average values ​​according to the results of core studies - for the AS 10, AS 11 and AS 12 layers, respectively, 15.4, 25.8, 2.4 mD,

high lateral and vertical heterogeneity of formations,

reservoir oil density - 780-800 kg/m 3,

reservoir oil viscosity - 1.4-1.6 mPa*s,

oil saturation pressure 9-11 MPa,

naphthenic oil, paraffinic and low-resin.

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 following methods for the Priobskoye field can be excluded from the methods listed above: thermal methods and polymer flooding (as a method of displacing oil from formations). Thermal methods are used for deposits with high-viscosity oils and at depths of up to 1500-1700 m. Polymer flooding is preferably used in formations 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 C ( For higher temperatures, expensive polymers with special compositions are used).

3.2.1 Reservoir flooding

Experience in the development of domestic and foreign fields shows that waterflooding turns out to be a fairly effective method of influencing low-permeability reservoirs, subject to strict compliance with the necessary requirements for the technology of its implementation.

Among the main reasons causing a decrease in the efficiency of waterflooding of low-permeable formations are:

deterioration of the filtration properties of the rock due to:

swelling of the clay components of the rock upon contact with injected water,

clogging of the collector with fine mechanical impurities found in the injected water,

precipitation of salts in the porous medium of the reservoir during the chemical interaction of injected and formation water,

reduction in reservoir coverage by flooding due to the formation of fractures around injection wells and their propagation deep into the formation (for discontinuous formations, a slight 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 the precipitation of paraffins.

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 patterns and technological operating modes of wells, injection of water of the required type and composition into the formations, its appropriate mechanical, chemical and biological treatment, as well as the addition of special components to the water.

For the Priobskoye field, waterflooding should be considered as the main stimulation method.

Application of surfactant solutions at the field was rejected, primarily due to the low efficiency of these reagents in low-permeability reservoir conditions.

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 reservoirs. Clay aggregates are represented by kaolinite, chlorite and hydromica. The interaction of alkali with clay material can lead not only to the swelling of clays, 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 high concentration solutions (reducing the swelling of clays) activates the process of rock destruction. In addition, clays with high ion exchange capacity can adversely affect the alkaline solution rim by replacing sodium with hydrogen.

Highly developed heterogeneity of the formation and a large number of interlayers, leading to low coverage of the formation with alkali solution.

The main obstacle to use emulsion systems The impact on the deposits of the Priobskoye field is due to the low filtration characteristics of the field's reservoirs. 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 extraction.

3.3 Methods of influencing the bottomhole formation zone to intensify production

3.3.1 Acid treatments

Acid treatments of formations are carried out both to increase and to restore the permeability of the reservoir in the near-wellbore zone of the well. Most of this work was carried out when converting wells to injection and subsequently increasing their injectivity.

Standard acid treatment at the Priobskoye field consists of 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. Response time is approximately 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. Acid treatment of CCD in injection wells turns out to be a fairly effective method of restoring their injectivity. As an example, Table 3.1 presents the results of treatments for a number of injection wells.

Results of treatments in injection wells

Table 3.1

An analysis of the treatments performed shows that the composition of hydrochloric and hydrofluoric acid improves the permeability of the wells. The injectivity of wells increased from 1.5 to 10 times, the effect can be seen from 3 months to 1 year.

Thus, based on the analysis of acid treatments carried out at the field, we can conclude that it is advisable 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 (fracturing) is one of the most effective methods for intensifying oil production from low-permeability reservoirs and increasing the production of oil reserves. Hydraulic fracturing is widely used in both domestic and foreign oil production practices.

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 intensification for the field, despite the significant rate of decline in production rate 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 undrained oil reserves in intermittent reservoirs of the field. Secondly, this type of impact makes it possible to extract an additional volume of oil from the low-permeability AC 12 formation within an acceptable period of field operation.

Gradeadditionalproductionfromcarrying outhydraulic fracturingonPriobskyfield.

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 (61% of the fund) were carried out at the field. The main number of hydraulic fracturing operations 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 for the year. Moreover, the majority of the additional production was oil from the AS-12 reservoir - 78.8% of all production in the reservoir and 32.4% of production in general. For the AS11 reservoir - 30.8% of the total production for the reservoir and 4.6% of the production as a whole. For the AS10 formation - 40.5% of the total production for the formation and 11.3% of the production as a whole.

As you can see, 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 of 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, are presented in Table 3.2

Table 3.2

A significant increase in oil production due to hydraulic fracturing is obvious. 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 increase was in 2009 (701,000 tons). By 2010, the value of additional production dropped to 606,000 tons, which is 5,000 tons lower than in 2008.

Thus, hydraulic fracturing should be considered the main method of increasing oil recovery in the Priobskoye field.

3.3.3 Improving perforation efficiency

An additional means of increasing well productivity is to improve perforation work, as well as the formation of additional filtration channels during perforation.

Improving CCD perforation can be achieved by using more powerful perforation charges to increase the depth of perforation channels, increase perforation density and use phasing.

Methods for creating additional filtration channels may include, for example, the technology of creating a system of cracks during the secondary opening of the formation with perforators on pipes - the system of fractured formation perforation (FFS).

This technology was first used by Marathon (Texas, USA) in 2006. Its essence lies in perforating the productive formation with powerful 85.7 mm perforators with a density of about 20 holes per meter while pressing the formation, followed by securing the perforation channels and cracks with a proppant - bauxite fraction from 0.42 to 1.19 mm.

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