Large oil and gas fields are located. Oil and gas complexes

Oil and gas potential and characteristics of individual largest deposits. Exploration work carried out to date shows that oil and gas deposits within the North Sea have a fairly wide stratigraphic range. Industrial accumulations of hydrocarbons are established in sediments from the Lower Permian to the Tertiary. There are ideas that oil and gas can also be found in older rocks, in particular in the Devonian.

The most ancient deposits in which industrial gas deposits are currently found are Permian Rothligendes deposits. The main gas reserves in the Anglo-German basin are associated with them. Rothliegendes collectors are covered with zechstein evaporites, which have a significant thickness and, therefore, are an almost perfect seal. Rotliegendes sandstones and Zechstein carbonates are oil-bearing in the Norwegian Basin.

The gas content of Triassic deposits has so far been established only at the Hewitt field, where the deposits are associated with Lower Triassic sandstones. Small gas reserves are also known here in Zechstein carbonates. Oil from Triassic sandstones was obtained from the Josephine field.

The main deposits of oil and gas in the Jurassic deposits are found in the East Shetland basin. The reservoirs here are predominantly Middle Jurassic sandstones. The depth of the reservoirs is 2600–3200 m, and their thickness is about 100 m. Dissolved gas occurs in the Jurassic deposits in the amount of 40 to 300 m 3 /t.

The oil and gas potential of the Upper Cretaceous (Danish) deposits has been established at the fields of the Ekofisk group (Norwegian basin), where oil is associated with carbonate reservoirs.

In Tertiary deposits, oil and gas are confined to Paleocene sandstones, which have high porosity and permeability. These deposits are oil and gas bearing within the Norwegian basin and the southern part of the East Shetland.

In accordance with the geological structure, the age of productive horizons and the distribution of oil and gas accumulations within the North Sea, three oil and gas areas can be distinguished: South (Anglo-German), Norwegian (Central North Sea) and East Shetland (North). In addition, several isolated fields have been discovered in the North Sea (Figure 2.7).

Southern oil and gas region is predominantly gaseous. In geological terms, it coincides with the Anglo-German basin of the North Sea. The main gas-bearing horizon here, with the exception of Hewitt fields, are the Rotliegendes sandstones. This productive horizon occurs at depths of 1,800–4,000 m, its thickness reaches 250 m. The porosity of the sandstone is 10–20%, and the permeability is relatively low (1–10 mD) due to secondary cementation processes. The total recoverable gas reserves of the Southern gas-bearing region are about 1.2 trillion m 3 . The composition of the gas is mainly methane with an admixture of nitrogen and heavy hydrocarbons. The deposits are associated with anticlines.

To date, several large gas fields have been discovered in the Southern Region, of which the Leman field is one of the largest offshore gas fields in the world.

Rice. 2.7. Gas fields and wells that gave gas inflows in the southern part of the North Sea. Place of Birth: 1 – Raf, 2 – West Soul, 3 – Amethyst, 4 – Swart Bank, 5 – Eni
6 – Viking North, 7 – wash south, 8 - IndividualGable, 9 — Broken Bank, 10 — Hewitt North, 11 — Deborah, 12 – Leman, 13 – Sean, 14 – hewitt, 15 – dotty, 16 – Placid, 17 – Groningen
Leman field– the largest gas field on the shelf of the southern part of the North Sea; its dimensions are about 28.8 km long and 12.8 km wide. The deposit is a gently sloping northwest-trending anticline parallel to the dominant strike of the Hercynian structures. The anticline is broken by several faults or fault systems. It lies on the southeast flank of the West Soul Trough, which experienced subsidence during the Triassic, Jurassic, and Early Cretaceous and then rapid uplift, inversion, and erosion during the late Cretaceous. These movements can be judged from the erosion section of the Upper Cretaceous writing chalk. Writing chalk is absent in the northwestern part of the structure. The territory of the Leman deposit, especially its southeastern part, was probably also affected by late Cimmerian uplift and erosion, resulting in the absence of Jurassic and Upper Triassic deposits. The superimposition of the Laramian erosion on the Cimmerian phase makes it difficult to reconstruct the exact history of the tectonic development of the deposit. The deposit was discovered in 1966 by well 49/26-1; productive horizon – rotligendes sandstones, thickness 236 m; porosity of aquatic sandstones 11–20%, permeability 0.5–30 mD; porosity of eolian sandstones 11–23%, permeability 10–100 mD; porosity of sandstones of temporary flows (wadi) 7–18%, permeability 1–30 mD; recoverable reserves 330 bcm; production - six platforms, each with 12-14 production wells; transportation - pipeline 41 km long, 76 cm in diameter to Beckton.

Deposit Indifitigable-viking is a series of fault-limited structures that together form a northwest-trending anticline. The Indifitigable area has a total length of about 19 km, and each block is about 3.2 km wide. The size of the Viking North deposit is 16×4.8 km. The Indyfightable and Viking Squares were subjected to intense uplift during the Cimmerian era. The uplift appears to have been most intense in the southeast. Erosion resulted in the occurrence of Lower Cretaceous deposits on the Caper, Muschelkalk, and Bunter (Triassic). In the Late Cretaceous, block motions manifested themselves more mildly and, apparently, had the opposite direction. The gradual subsidence in a southeasterly direction (i.e., towards the Broad Fortins trough) resulted in an increase in the thickness of the Upper Cretaceous writing chalk in this direction. The productive horizon of the Rotliegendes is intensively disturbed by faults as a result of Late Jurassic (Cimmerian) tectonic movements, and the amplitude of faults often reaches several hundred meters. These displacements exceed the thickness of the Rotliegendes productive horizon (46 m), as a result of which individual blocks often have different gas-water contacts. In general, the amplitude of the faults and the depth of the gas-water contact in the northwest direction gradually increase. The Indifitigable field was discovered in 1966 by well 49/18-1; productive horizon – rotligendes sandstones; thickness 16–35 m; production - three platforms, each with eight wells; transportation - a pipeline with a length of 135 km, a diameter of 76 cm to Beckton through the Lehman field. The Viking North field was discovered in 1968 by well 49/12-2; productive horizon - rotliegendes sandstones with a total thickness of 150 m, effective 99–135 m, recoverable reserves - 140 billion m 3; production – one platform with ten wells; transportation - a pipeline 98 km long, 71 cm in diameter to Tedlethorn (Lincolnshire).

The most typical for the southern region is West Soul field, confined to the anticline fold, elongated from the northwest to the southeast along the Lower Permian deposits. The latter lie with unconformity on the Upper Carboniferous rocks. According to its features, the gas deposit can be classified as a massive one. The main productive horizon is associated with the Rotliegendes sandstones, occurring at a depth of about 3,000 m. They form a salt dome, which is shifted to the northeast with respect to the Lower Permian uplift by 5 km. Disturbances, apparently, of the Jurassic age, affected carbon, rotligendes and zechstein, and the integrity of the latter turned out to be undisturbed. The West Soul field was discovered in December 1965 by well 48/6-1, recoverable gas reserves - 67 billion m 3, inflow during sampling 0.3 million m 3 /day; production from fractured and local permeability zones; four fixed platforms, each with five or six production wells; transportation - a pipeline 64 km long and 40 cm in diameter to Easington on the Yorkshire coast.

The listed deposits lie in the southwest of the Southern Region and are located in the British sector of the North Sea. In the same area, 100 km east of the Indefatigable deposit in the Netherlands sector, the L/10 deposit (Placid) was discovered. The productive horizon of the L/10 deposit is Rotliegendes sandstones; they lie at a depth of about 4,000 m. The gas deposit is confined to a large flat fold oriented in a direction close to the meridional one. Its reserves are not less than 150 billion m 3 .

Hewitt field somewhat different from those described. It is associated with an anticlinal fold elongated in the northwest direction, located in the immediate vicinity of the Leman deposit. The Hewitt field has three productive horizons, the lower of which is associated with zechstein dolomites and occurs at a depth of 1,400 m. Two main gas-bearing formations are located in the Lower Triassic and occur at depths of 1,250 and 900 m, respectively. Triassic reservoirs are sandstones with good reservoir properties – 25% porosity and 1,000 mD permeability. The accumulation of gas in the Triassic deposits of this field is explained by the fact that it lies outside the development of saline rocks of the zechstein, which “quench” disjunctive disturbances, therefore, the presence of faults contributed to the vertical migration of gas upward through the Permian rocks. The upper gas deposit is characterized by an admixture of hydrogen sulfide. The field was discovered on October 20, 1966 by well 48/29-1; recoverable gas reserves - 98 bcm, production - four stationary platforms, each with eight wells; transportation - a pipeline 29 km long and 76 cm in diameter to Bexton on the Norfolk coast.

The interest of oil companies in the North Sea shelf is directly related to the discovery Groningen deposits in the northeastern part of the Netherlands in 1959 by borehole 1 Slochteren. Thick Lower Permian gas-bearing sandstones penetrated by the discovery well were also noted in Delftziel well 1, which was supposed to be drilled on a separate structure. Subsequently, it turned out to be part of one large gas field. The intervals of Tertiary deposits and Upper Cretaceous writing chalk are variable in thickness due mainly to the salt tectonics of the zechstein; Jurassic and Upper Triassic rocks are absent, probably due to late Cimmerian erosion. Zechstein, represented by four complete evaporite cycles, varies in thickness due to the manifestation of salt tectonics. However, it has a minimum thickness of about 600 m and serves as a very effective seal for the underlying gas containing reservoir. Large faults traversing Rothliegendes and older rocks are attenuated in plastic salt beds and therefore do not serve as migration paths for accumulated gas.

The Slochterene unit, the main gas-bearing horizon of the Groningen field, gradually increases in thickness from 82 m in the south to 201 m in the north. Conglomerates are usually present in the lower part; the overlying dune sandstones are often loose, poorly compacted, with excellent porosity and permeability. However, interbedded layers of sediments of temporary flows have less favorable reservoir properties. Rotligendes is underlain by deltaic sandstones, shales and coals of the Upper Carboniferous, which are gas-conducting deposits. The structure of the Groningen gas field is controlled by faults. The northwest strike of Late Cimmerian (Late Jurassic) faults with an amplitude exceeding 300 m predominates. Some of these faults may have had an older origin and became active during the Late Cimmerian tectonic phase. There are indications that the structure of the Groningen deposit had already been partially formed by that time, but it is certain that the late Cimmerian movements changed it, giving more or less modern look, and subsequent erosion destroyed the deposits of the Jurassic and Upper Triassic age. Subsequently, the structure was buried under the Cretaceous rocks, and the Laramian and Alpine phases of the earth's crustal movements had little effect on it.

Characteristics of the Groningen deposit: porosity 15–20%; permeability - usually from 100 to 1,000 mD; gas composition - methane 81%, nitrogen - 14%, carbon dioxide - 1%; proven gas reserves 2 trillion m 3 .

It is noteworthy that the discovery of this field occurred after drilling 200 unsuccessful exploration wells. The history of the formation of the deposit is very interesting. According to experts, the gas originally contained in the anticlinal trap escaped into the atmosphere. An additional source of hydrocarbon gas was required. Such a source was the thickness of the Carboniferous deposits, lying significantly below the productive horizons. During the Cenozoic era, new portions of gas began to enter the anticline trap along the faults of the earth's crust until the unique Slochteren field was formed. This example shows how important it is to be able to correctly decipher the history of the development of geological objects.

In the east of the Southern Region, oil non-industrial deposits associated with the Jurassic deposits were also discovered. The non-industrial nature of the deposits is due to the fact that they lie shallow from the surface, and the sediments containing them are eroded over most of the southern region.

Norwegian oil and gas region geologically coincides with the Norwegian Basin. It is located between the Southern Region in the south and East Shetland in the north. As indicated above, geologically, the area under consideration is a large Tertiary trough. It is characterized by a wide range of oil and gas content: from Permian to Tertiary sediments. Currently, 22 oil and 5 gas fields are known here. The largest oil fields: Fortis, Ekofisk, Piper, Montrose, etc. The fields are associated with large gentle brachianticlinal folds. Reservoir type is both terrigenous and carbonate.

Fortis field is the largest in the described zone, it is located in the central part of the Norwegian basin. Structurally, Fortis is a large flat fold, elongated in the latitudinal direction. According to the Paleocene deposits, its size is 16 × 8 km, with a ratio of width and length of 1:2. The area of ​​the fold along the lowermost closed isoline is 90 km 2 , and its amplitude is 155 m. The eastern pericline of the fold is complicated by a low amplitude drop. An uplift in Tertiary deposits is positioned congruently over an uplift in Cretaceous deposits that overlies a basalt igneous outcrop. In sediments overlying the Paleocene, the fold gradually flattens out; it is not recorded in the Upper Miocene and Pliocene rocks, which have a monoclinal dip in the southeast direction.

An analysis of the geological history of the Fortis field shows that in the early Tertiary time its structure was relatively uplifted, which contributed to the early migration of hydrocarbons. The main productive horizon of this deposit is Paleogene sandstones, with Paleocene clays and mudstones serving as a cap, the carbonate content of which varies over the area. The thickness of the Paleocene seal rocks is about 50 m. In the lower part they are composed of dark gray silty clay, and in the upper part they are composed of greenish gray weakly carbonate mudstone. The productive formation is not homogeneous over the entire area of ​​the field, but is characterized by facies variability. In the south and east of the structure, sandstones are replaced by green and gray clays and siltstones. However, the main part of the productive formation is composed of a sandstone unit 35–80 m thick with rare clay interbeds; carbonate cementation is developed in some areas. Pebble layers are also observed. Sorting of sandstones is poor to medium, but their reservoir properties are good: porosity 25–30%, permeability up to 3,900 mD.

The oil deposit in the Fortis field is massive, the height of the deposit is 155 m. The oil occurs in the depth interval of 2,100–2,200 m and is characterized by a low content of sulfur and paraffin. There is no gas cap in the field; the dissolved gas content is relatively low (about 70 m 3 /t). The geological reserves of the field are about 700 million tons, and the recoverable reserves (with an oil recovery factor of 40%) are about 280 million tons.

Ecofisk- the second largest oil field in the Norwegian oil and gas region. It is located in the submerged part of the Norwegian depression and is the largest of the deposits established in this area, which are its "satellites". Structurally, Ekofisk is a two-peak domed uplift along the Upper Cretaceous deposits. It is located above the salt dome in the Permian deposits. The structure is oriented in the meridional direction and has dimensions of 12×7 km; area - 55 km 2.

The carbonate rocks of the Danish stage of the Upper Cretaceous are oil and gas bearing, and the clays of the Paleocene and overlying deposits are the caps. The thickness of the productive horizon is 120 m, and the effective thickness is 119 m. It lies on average at a depth of 3,000 m. %) Cretaceous rocks of the Danish stage of the North Sea have low permeability (up to 1 mD). However, at the Ekofisk field, due to tectonic fracturing caused by the growth of a salt dome, the permeability of Danish carbonates averages 10–12 mD. Oil reserves of the field are 600 million tons, and recoverable reserves are 150 million tons with an oil recovery factor of 25%; dissolved gas reserves are 100 billion m 3 .

It is assumed that the field will continue to supply oil to the UK and other countries of Western Europe. Potential annual production of 90 million tons of oil.

Western European experts associate great prospects with further exploration of deposits in the North Sea. Even huge costs do not cool the ardor of search engines. French economist J. Chevalier estimates the development of an oil field in the most "inhabited" part of the sea at 250 million pounds sterling (that is, approximately $ 375 million), which corresponds to the cost of one trip to the moon. The development of the gas giant Troll in the northern part of the sea will cost $10 billion.

Troll deposit opened in 1979 and located 65 km from the coast of Norway (terminal Kollsness). The field's recoverable gas reserves are about 1.3 trillion m 3 , gas condensate - 31.6 million tons. Annual production averages about 26.4 billion m 3 of gas and 0.55 million tons of gas condensate. So far, 106 production wells have been drilled at the field; 36 of them are multilateral. The well that discovered the new reservoir was drilled at a sea depth of 341 m to a final depth of 2,055 m from the seabed.

Montrose field was the first oil field discovered in the British sector. The first well was drilled at the end of 1969. The oil producing zone of the field is relatively thin, and at first there were doubts about its commercial value. Currently, three wells have been drilled at the field, and it is being prepared for exploitation.

The Montrose field is confined to an anticline complicated by three domes. The oil reservoir is composed of thick porous sandstones of the Paleocene, i.e. the age of the productive horizon is the same as in the larger Fortis field, located to the northwest. The average oil-water contact depth is 2,520 m below sea level, 281 m deeper than at the Fortis field. The structure of the Montrose deposit appears to be a sediment-compensated buried block, which may be a southeastern continuation of the Fortis deposit block. It is not clear whether the Montrose production sandstones are shallow deltaic formations, as in the Fortis field, or whether they are deeper water sandstones deposited by turbidite flows.

Description of the deposit: discovered on December 28, 1969 by well 28/8-1; the productive horizon is Paleocene sandstones with a maximum thickness of 57 m.

In addition to the Ekofisk and Montrose fields, smaller fields have been identified in this area of ​​the Norwegian Basin, which are geologically similar to Ekofisk, i.e. they have the same oil and gas bearing horizon, similar in features geological structure structures, but much smaller sizes and, accordingly, smaller stocks. These are the Zapadny Ekofisk, Torfelt, Eda, Albustkel, etc. fields. The total recoverable reserves of the entire group of fields, including Ekofisk, are 350–400 million tons.

Three deposits were discovered in the south of the Norwegian region in the Danish sector of the North Sea, of which the largest is Dan. In terms of structure and oil and gas content, it resembles the birthplace of the Ekofisk group. Danish limestones are also productive here, which occur at a depth of 1,830–2,000 m. The height of the oil deposit is 90 m, and the gas cap is 75 m. However, during the development of the field, a sharp decrease in well flow rate was observed, which raises the question of the expediency of its further exploitation.

In the immediate vicinity of the Ekofisk group of fields in the axial zone of the Norwegian Basin, there are Josephine deposits, Ok and Argil. They are relatively small, with oil reserves from 10 to 30 million tons, differ from the group described above in the older age of productive horizons (Lower Permian sandstones, Zechstein carbonates and Mesozoic sandstones). At the Josephine field, oil was obtained from Triassic sandstones from a depth of 3,600–3,700 m. Oil from these fields apparently migrated from the Jurassic deposits of the axial part of the basin. Geologically, these deposits are fault-line anticlines formed above uplifted basement blocks. On these blocks, there is an unconformable overlay of Cretaceous deposits on older ones as a result of pre-Cretaceous movements and erosion.

To the north of the Montrose field is the Morin field, confined to the axial zone of the Norwegian Basin. As in Montrose, the productive horizons here are associated with Paleocene sandstones. The recoverable reserves of this deposit are estimated at several tens of millions of tons.

And, finally, the last large oil field of the Norwegian Basin, located in the northwestern marginal part of the basin of the same name, is Piper deposit. This is a relatively small structure like a structural nose with an area of ​​about 25 km 2 . In structure, it somewhat resembles the fold of the Fortis deposit. The field has two productive horizons associated with Jurassic sandstones. The main productive reservoir with a minimum thickness of 90 m lies at a depth of 2,440 m. A second one, with a thickness of 15 m, lies 300 m below this horizon. The deposit's recoverable reserves are 120 million tons, it has not yet been fully delineated.

In the same area is Claymore deposit located 24 km to the west.

Very limited stocks Brim and Bristling deposits located in the east of the Norwegian depression in the Norwegian sector. Productive horizons in them lie at depths of more than 4 km.

In addition to oil and oil and gas fields in the Norwegian oil and gas region, gas condensate Cod field, Lomond gas and others. They have deposits in the Lower Tertiary deposits and are relatively small in size.

East Shetland oil and gas region is the northernmost in the North Sea and was discovered in 1972–1973. It coincides with the East Shetland Trough. In terms of area, this area is much smaller than those described, but it has the largest reserves of oil and gas. Currently, more than 15 oil and gas fields have been discovered here, the productive horizons of which are located in the Middle Jurassic and Paleocene deposits. Largest number large deposits located in the northern part of the East Shetland Trough; they form a group of Brent fields confined to the platform block of the same name. In this area, located east-northeast of the Shetland Islands, 10 oil fields are known, the total recoverable reserves of which are about 1.5 billion tons. All of them, with the exception of the Statfjord field, are located in the British sector of the North Sea. Discovered deposits in this area are located literally one next to the other, and it is often unclear whether the deposits are independent or represent a single deposit.

The area under consideration cannot currently be considered fully explored. The intelligence of the Norwegian sector is at the initial stage, and in the British sector several more structures have not been introduced into intelligence. Despite the harsh climatic conditions, there are very active search oil.

One of the largest deposits in the North Sea is fieldBrent. Structurally, it is 20 × 8 km in size. This fold is expressed in the Tertiary and Cretaceous rocks, and in the Jurassic and underlying deposits it is an uplifted block, bounded from the west and east by faults. The Cretaceous deposits rest unconformably on the Jurassic rocks as a result of erosion that took place during the Cimmerian. The main reservoirs are represented by Jurassic sandstones. These deposits occur at a depth of 3–3.5 km. There are several horizons in the Jurassic. In addition, deposits of hydrocarbons are assumed in sediments from the Devonian to the Carboniferous. The recoverable oil reserves in the Jurassic deposits are about 350 million tons. The field was discovered in June 1971 by well 211/29-1, which was not tested for a long time due to the upcoming "fourth round" of licensing; the productive horizon is Middle Jurassic sandstones (brent) with a thickness of approximately 240 m, porosity 7–37%, permeability up to 8 D, Lower Jurassic - Rhaetian sandstones (statfjord) with a thickness of 176 m, porosity up to 26%. Brent sandstones contain gas (floor - 76 m) and oil (floor - 144 m); oil density - 0.83 g / cm 3, gas factor 300 m 3 / t; statfjord sandstones: gas-bearing level - 150 m; oil-bearing floor - 130 m; oil density - 0.85 g / cm 3, gas factor 600 m 3 / t.

In close proximity is Nainian deposit, resembling the Brent field in its structure. There is also a fold in Tertiary deposits above an uplifted basement block, the same productive horizon is Middle Jurassic sandstones; their depth is about 3 km. The proven recoverable reserves of this horizon are 180–270 million tons.

Dunlin and Thistle fields located immediately north of the Brent field. They have a complex structure and, in addition to longitudinal faults, are complicated by transverse faults that break up single structures into a number of blocks. The productive horizon here, as in the Brent field, is the Middle Jurassic sandstone, the effective thickness of which is 100–120 m. The main oil and gas bearing horizon occurs at a depth of 2,700 m. mostly water with some oil. The recoverable reserves of the Dunlin deposit are 100–150 million tons; approximately the same amount is concentrated in the Thistle field.

Not far from the Brent field in 1974 was discovered field statfjord(Figure 2.8) in the Norwegian sector of the East Shetland Trough. This giant offshore field in the North Sea has been in development for over 30 years. In structure, it resembles the Brent field. Middle and Lower Jurassic sandstones are productive here. The first oil was produced on November 24, 1979. Although the remaining recoverable reserves are small compared to the initial reserves of the field, they look impressive in comparison with the newly discovered deposits on the North Sea shelf.

As a result of work on well repair, additional drilling of the field and the use of the method of alternate injection of water and gas, oil recovery in the whole field increased from the previously planned 48% to the current 66%. The operation of the Statfjord field will continue until 2020, despite some difficulties.

Smaller deposits are also known within the northern part of the East Shetland Basin - Kormorant, Alvin, Magnus, etc. Their recoverable reserves are less than the reserves of the described deposits (with the exception of the Kormorant deposit), the estimate of which ranges from 13 to 100 million tons. These deposits are also associated with Middle Jurassic deposits, and the folds have a block structure. In the southern part of the East Shetland Trough, there is a large gas condensate field Frigga. This is a large dome-shaped uplift of pre-Tertiary rocks with an area of ​​175 km2. The productive horizon is the Paleocene sandstones,

Rice. 2.8. Scheme of the structure of the Statfjord deposit
the reservoir properties of which are close to the reservoir properties of the Paleocene deposits of the Fortis field. The depth of the productive horizon in the crest of the structure is 1,800 m. The effective thickness of the Paleocene deposits is 130 m. The reserves of gas are about 300 billion m3, gas condensate is 100 million tons. It is not entirely clear why some structures in the East Shetland Trough are gas-saturated, while others are oil-saturated . It is possible that the gas content of the Frigga uplift is due to the fact that the gas field is located above the zone of development of Mesozoic deposits, which have a significant thickness and depth of subsidence. Due to this, here hydrocarbons are formed in the high pressure zone and are in a gaseous state. When migrating upwards, they do not change the phase state.

In 2004, gas production at the North Sea Frigga field was discontinued. Over 26 years of operation of the field, 190 billion m 3 have been produced. The depletion of the deposit was predicted as early as the late 1980s, but the introduction of improved mining technology has helped extend the life of the deposit. Immediately to the south is the Heimdal field with productive horizons in the Paleocene. The depth of the productive horizon is 1,800–2,130 m, its thickness is about 180 m. Commercial gas inflows were obtained immediately to the north and east of the Frigg field. Thus, the discovery of several gas and gas condensate fields can be expected in this area.

In the southern part of the East Shetland Trough, in addition to gas condensate fields, oil fields have been discovered. These include the Beryl field with recoverable reserves of 70–80 Mt and block 2/5 with reserves of 50–70 Mt, located in the British sector. Oil inflows were also obtained in block 2/5 of the Norwegian sector, immediately south of the Heimdal field.

The presented data indicate that the North Sea is a fairly large oil and gas province (Table 2.3). Explored geological reserves were estimated at 9.6 billion tons of standard fuel (using coal equivalent conversion factors). The recoverable reserves amounted to more than 25 trillion m 3 of gas and about 3 billion tons of oil and condensate. As already mentioned, these resources are concentrated in a wide stratigraphic range, from the Permian to the Paleogene. The stratigraphic distribution of reserves shows that about half of the explored geological reserves are confined to the Jurassic deposits, approximately 20% to the Permian (Rotligendes) and Paleocene, and the rest of the reserves to the Upper Cretaceous (Danish Stage) and Triassic. If we consider the distribution by area, we can see that more than 50% of the oil reserves (geological and recoverable) are concentrated in the East Shetland Basin, superimposed on the ancient buried zone of the Caledonian uplifts. About 50% of the gas reserves are confined to the Rotliegendes deposits and are concentrated in the Anglo-German depression. Here, the main largest deposits are associated with the side zone of the Anglo-Brabant massif. To date, most of the explored hydrocarbon reserves are located in the British sector of the North Sea. It accounts for about 80% of the explored recoverable oil reserves and more than half of the gas reserves. Then the big rates were achieved in the Norwegian sector of the North Sea.

It should be noted that deposits of natural resources are located unevenly. The main areas of their location:

• Far East - 45 on Sakhalin Island and 12 on Sakha Island in Yakutia.
• Western Siberia - about 500 fields, which is 70% of Russian oil reserves.
• Russian Arctic - Novoportovskoye field and Gazprom Neft.

Oil fields in Russia

The total number of oil fields is more than 2 thousand. The largest are the following:

• Tuymazinsky. This oil field is located in the Republic of Bashkiria and is one of the largest places where oil is produced in Russia. The process of oil production here began in 1937 and continues to this day.
• Samotlor. This field located near the lake Samotlor. Oil production has been carried out here since the middle of the last century. Now the oil and gas company Rosneft is engaged in production.
• Romashkinskoe. It is one of the oldest oil fields. Location - Republic of Tatarstan. Its reserves are about 5 billion tons. Their extraction is carried out by the Tatneft company.
• Priobskoye. According to the average daily oil production, it ranks first in Russia. Approximately 100 thousand tons of oil are produced per day. The work is being carried out by Gazprom Neft and Rosneft.
• Lyantorskoe. The daily volume of oil produced is 26 thousand tons. Surgutneftegaz is a mining company in this area.
• Fedorovskoye. The total mineral reserves are approximately 2 billion tons.

Prospects for the oil industry in Russia

• It is predicted that in the coming years due to the increase in the number of road transport in the world and in Russia in particular, the oil industry will only develop.
• Implementation modern technologies and reducing losses at all stages of the oil production process will greatly increase the profitability of the industry.
• The position of Russian oil companies in the markets of other countries is being strengthened. Russian government is aimed at increasing production volumes, which in the future will lead to the expansion of fuel exports to other countries near and far abroad.

Natural gas fields in Russia

Russia ranks 8th in the world in terms of natural gas production. The main deposits are:

• Urengoy. Its volume is approximately 16 trillion cubic meters of gas.
• Yamburgskoye. The volume of natural gas reserves is about 8 trillion cubic meters.
• Bovanenkovo. Approximately 5 trillion cubic meters is the volume of this deposit.
• Shtokman. The volume of natural gas reserves here is approximately 4 trillion cubic meters.
• Leningrad. One of the promising places for gas production. The volume is about 3 trillion. cubic meters.

There are 26 underground gas storage facilities in Russia to store blue fuel. Kasimovskoye (Ryazan region) is the most powerful and spacious. Its approximate volume is 11 billion cubic meters. m.

It should be noted that the world's largest natural gas processing plant, the Orenburg Gas Processing Plant, is located in Russia. In addition to this plant, several other enterprises operate in the country - Urengoy, Sosnogorsk, Astrakhan gas processing plants and several dozens of small ones.

Actual problems of oil and gas production in Russia

• Low rate of mining and a significant increase in the cost of work.
• The deposits are located in hard-to-reach places.
• Depreciation of oil production equipment and the use of outdated energy-intensive technologies.
• Low rates of introduction of innovations in the field of oil production.
• Irrational use of oil and gas.

The total area of ​​the entire Arctic shelf exceeds 26 million km2. The area of ​​the prospective water area of ​​the Russian sector of the Arctic is at least 5 million km2. Almost the entire space of the Arctic is located on a block of the pre-Riphean continental crust. According to another point of view, the existence of the pre-Riphean platform is denied. If the existence of the pre-Riphean platform is proved, then a significant part of the Arctic Ocean will go to Russia. Thus, the question of the pre-Riphean platform has not only scientific, but also economic significance.

Subsequent events (rifting, formation of Caledonian zones, Mesozoic tectogenesis, opening of oceanic basins, etc.) determined the formation of the modern structure of this region. Two large blocks of the earth's crust have emerged within the Arctic shelf. The Eurasian (Norwegian-Barents-Kara) block covers the seas of the same name, the western part of the Laptev Sea, archipelagos and islands (Svalbard, Franz Josef Land, Severnaya Zemlya, Novaya Zemlya, etc.). The Amerasian block includes the eastern part of the Laptev Sea, the East Siberian Sea with the New Siberian Islands, and the Chukchi Sea with the Wrangel and Herald Islands. The blocks are separated by the rift zone of the underwater Gakkel Ridge, branches of this zone in the south, as well as deep-sea basins adjacent to the ridge. The regime and features of the oil and gas content of the sedimentary basins identified within these blocks were significantly affected by rifting.

Within the Arctic waters, large subsided areas with increased thickness of sediments and uplifts are distinguished, promising for the search for oil and gas fields. On the basis of tectonic and lithological-stratigraphic analyzes, areas have been identified that can be considered as separate provinces that include these sedimentary basins. Some of them are proven oil and gas bearing, others are considered as very promising.

The oil and gas bearing basins of the western (Eurasian) block contain significant oil and gas resources, which is proved by the discovery of the unique Shtokman gas field in the Barents Sea, oil and gas fields in the Pechora Sea (Prirazlomnoye, Severo-Dolginskoye and others), gas fields in the Kara Sea (Rusanovskoye and Leningradskoye). In the Norwegian sector of the Barents Sea, hydrocarbon deposits are confined to the Snovit oil and gas field and the Golias oil field. According to estimates made by VNIIOkeangeologiya, VNIGRI and other organizations, Russian part of the Western Arctic shelf, including the Barents, Pechora and Kara Seas, is more than 75% of the explored reserves of the entire Russian shelf - 8.2 billion tons of conventional units. fuel. Within the eastern (Amerasian) sector of the Russian Arctic, not a single well has yet been drilled and not a single oil and gas field has been discovered, but there are prospects, judging by the presence of large deposits in similar strata of adjacent regions of Alaska. In the eastern part of the shelf of the Chukchi Sea, American companies have drilled several wells that have shown signs of oil potential.

According to the point of view accepted in Russia, the main part of the water area of ​​the Arctic Ocean and the adjacent land area of ​​the Arctic is located on the pre-Riphean crust of the continental type. The depth of the base of the earth's crust (Mohorovichich boundary) varies from 40-42 km, decreasing under the zones of continental rifting to 33-35, sometimes up to 25 km. The Konrad boundary is fixed at a depth of 20-25 km.

In the geological history of the Arctic basins in remote areas, several stages of rifting, often synchronous, are distinguished. The synchronism of rifting manifestations makes it possible to outline regional geological zones stretching for hundreds and thousands of kilometers and characterized by a similar geological history. As a result, it is possible to make a forecast of oil and gas content in tectonic blocks that are, at first glance, disconnected.

Figure 5 shows a geomorphological map of the Arctic Ocean.

Rice. 5.

In terms of oil and gas potential, each sedimentary rock basin corresponds to an oil and gas basin. Within the Western Arctic shelf, the Barents Sea, Timan-Pechora, South Kara, West Siberian, North Kara, Yenisei-Khatanga, South Laptev oil and gas basins are distinguished, in the territory of the eastern sector of the Russian Arctic - East Siberian and Chukchi.

The Barents Sea oil and gas basin is the most studied, only gas and gas condensate fields (Shtokmanovskoye, Ledovoye, Ludlovskoye, Severo-Kildinskoye and Murmanskoye) have been discovered within its boundaries.

Within the water area of ​​the Timan-Pechora oil and gas basin, the identified deposits are confined to the zones of continuation of aulacogens: Varandey-Adzvinskoye (Varandey-sea, Medynskoye-sea, Dolginskoye and Prirazlomnoye) and Pechoro-Kolvinskoye (Pomorskoye gas). The Severo-Gulyaevskoye oil and gas field is associated with the offshore extension of the Khoreyver depression, and the Peschanoozerskoye and Izhemko-Tarkskoye oil fields are associated with the offshore extension of the Malozemelsko-Kolguevskaya monocline.

Within the South Kara and north of the West Siberian oil and gas basins, unique and large onshore fields of the Yamal Peninsula were discovered, and in the offshore part two unique gas fields (Rusanovskoye and Leningradskoye) were discovered in the Ob and Taz Bays.

The most favorable for the formation of the oil and gas potential of the basin are the zones of rift troughs and the "superdeep depressions" formed in their place.

Mostly gas fields are associated with inversion anticlinal uplifts. They are located in chains within the shafts and form linear zones of oil and gas accumulation. Such promising zones within the Barents Sea rifting zone include all inversion structures (Demidov-Ludlovsky megaswell, Shtokman saddle, uplifts Central banks and Fersman).

Within the South Kara-Yamal zone of rifting, inversion swells (Nurminsky, Malyginsky, Yamburgsky, Gydansky, Preobrazhensko-Zelenomysovsky, Novoportovsky, Urengoysky, Tazovsky, Chaselsky, Verkhne-Tolkinsky, Kharampursky) are the most promising for the search for oil and gas fields.

Interesting, from the point of view of oil and gas potential, is the area of ​​development of salt tectogenesis within the Central Barents zone of rifting. Salt domes can be associated with gas accumulations in the pre-salt complex or small oil accumulations in the post-salt sediment complex.

For the formation of oil accumulations, the most favorable are the side sections of large troughs or individual arched uplifts within the zones of rifting, which have undergone a significant uplift, which could be repeated several times during the geological history of the basin. As a result, the thick Mesozoic section turned out to be eroded, and the Paleozoic section of the sedimentary cover lies at a depth accessible for drilling. Such promising structures for oil include the Fedynsky arch, as well as the side sections of the Admiralteysky shaft. The possibility of preserving oil in Paleozoic rocks is evidenced by the finds of liquid bitumen in them in the extreme north of Novaya Zemlya, on Pioner Island, in the western part of the Yenisei-Khatanga trough, on Severnaya Zemlya and Taimyr.

Within the limits of superdeep depressions, "tectonic nodes" have the maximum productivity, that is, areas that fall into the area of ​​intersection of zones of continental rifting of different directions, and possibly of different ages. These "tectonic nodes" reflect the intersection of zones with high deep energy, which causes anomaly in all processes occurring in them, including oil and gas formation and the subsequent migration of hydrocarbons. Such areas within the Barents Sea basin include the area of ​​intersection of the Paleozoic sublatitudinal zone of rifting and the submeridional zone of Triassic rifting superimposed on it, stretching along the Novaya Zemlya folded area and forming the South Barents and North Barents depressions. The giant Shtokmanovskoye and two large gas fields (Ludlovskoye and Ledovoe) fall into this area.

Within the South Kara-West Siberian basin, such tectonic knots include the intersections of the Yenisei-Khatanga trough with both the South Kara-Yamal rifting zone and the Laptev Sea rift. Within Western Siberia, most of the gas giants of Yamal are confined to such a tectonic knot.

In the western part of the Laptev Sea, the most promising for prospecting work for oil and gas, the zone of intersection of two riftogenic troughs, the rifting zone of the Laptev Sea and the eastern part of the Yenisei-Khatanga trough.

Near the intersections of the rift troughs, there is a large Trofimov uplift, located partly in the Lena delta, and other favorable structures are outlined.

The prospects for the North Chukotka trough in the eastern sector of the Russian Arctic are assessed mainly by analogy with Alaska, based on the assumed similarity of the nature of the sections. In the northern part of Alaska, about 40 fields are known, of which about 10 are being developed. The largest field in the basin of the Arctic slope is the Prudhoe Bay field, confined to an uplift 21 × 52 km2 in size. The initial commercial reserves of this field amounted to 1.78 billion tons of oil and 735 billion m3 of gas. The main reservoir is in Permo-Triassic, Triassic sandstones, and lower Jurassic horizons (Ivishak Formation of the Sadlerochit Group and the overlying Shublik and Sag River Formations). Around Prudhoe Bay there is a whole group of smaller satellite deposits. To the west is the Kuparuk River field, the oil reserves in the Neocomian sandstones are estimated at 200 million tons. Popcorn and Daimon; from the Triassic Ivishak Formation in the well The Klondike received inflows of oil. Numerous oil shows are noted above the Cretaceous unconformity in the rocks of the Pebble Shale, Torok and Nanushuk formations.

In the section of the Chukchi Sea, favorable structures are distinguished, including large linear uplifts, which may be associated with zones of oil and gas accumulation. Zones of wedging out and stratigraphic cutting are widely developed. Within the North Chukotka trough, there are structural forms of many types favorable for oil and gas accumulation (folds, zones of lithological wedging out, stratigraphic shearing, possibly diapiric folds), which are objects of oil and gas exploration. This trough can be considered as an oil and gas basin, which is of the greatest interest in the eastern sector of the Russian Arctic. The prospects for oil and gas potential should be associated with the thrusts of the Wrangel-Gerald uplift zone, where the Triassic and Upper Paleozoic deposits can be exposed at an accessible depth. Albian clay rocks (Torok Formation in Alaska) serve as an effective seal.

The prospects for the North Chukchi, East Siberian troughs, the Podvodnikov Basin and, possibly, the Amundsen and other superdeep basins of the Eastern Arctic are associated primarily with the Upper Cretaceous and Cenozoic deposits. Their thickness exceeds 10 km. In addition to the central parts of the troughs, their side zones, such as the slopes of the De Long and North Chukchi uplifts, also have prospects. In addition, the inversion uplifts of the Paleozoic troughs also have high prospects, where they are available for drilling (the Wrangel-Herald zone of uplifts).

The above review shows that the main potential resources of gas and oil are concentrated in the central, most subsided parts of the sedimentary basins of the Arctic. The most subsided parts of the basins are predominantly gas-bearing due to the displacement of oil fluids by gas fluids into the side zones of the troughs. The oil content is associated with the Meso-Cenozoic complex of the northeastern shelf, as well as with relatively uplifted blocks that have not experienced subsidence to a depth of 5-6 km in the western sector of the Arctic. These patterns within individual structures of different nature can only be identified with a regional, broad approach to the study of the Arctic and considering it as a whole over a long history of geological development.

The West Siberian oil and gas province occupies the territory of the West Siberian Lowland. The first gas field, Berezovskoye, was discovered in 1953.

The platform of the West Siberian province is located on the basement of the Paleozoic age, represented by Meso-Cenozoic sandy-gynous deposits, the thickness of which reaches 4000-5000 m.

The West Siberian oil and gas province includes several oil and gas regions:

§ Sredneobskaya;

§ Vasyuganskaya;

§ Frolovskaya;

§ Severo-Tyumenskaya;

§ Berezovo-Shaimskaya.

Sredneobskaya oil and gas region It is represented by the Samotlor field, which is unique in terms of oil reserves. The richest oil fields also include Mamontovskoye, Sovetskoye, Ust-Balykskoye, Pravdinskoye, Zapadno-Surgutskoye.

Oil and gas potential has been established in the Tyumen, Vasyugan, Megion and Vart suites. The main oil reserves are associated with deposits of the Vartovskaya and upper Megion suites. More than 30 permeable sand layers are distinguished in their section, of which almost 20 have proven commercial oil and gas potential. Significant accumulations of oil are enclosed in sandy and sandy-clayey formations of group "A" in the top part of the Vartovskaya suite. Their thickness is variable and often replaced by clays and siltstones.

At the base of the sedimentary cover lies the Tyumen Formation (Lower + Middle Jurassic), 200–300 m thick. It is expressed by intercalation of sandstones, siltstones, and clays. The Upper Jurassic within the Surgut and Nizhnevartovsk arches is represented by the Vasyugan and Georgievskaya suites, consisting of alternating sandstones and mudstones with a thickness of 50-110 m.

The Megion and Vartov suites (Valangin and Hauteriv-Barrem) are composed of sandstone beds separated by mudstones with a thickness of 265-530m.

The oil of the Sredneobskaya region has a density of 0.854-0.901 g/cm 3 , a sulfur content of 0.8-1.9%. The highest sulfur content in the oils of the fields of the Surgut region. All oils are low paraffinic 1.9-5.3%.

North Tyumen gas and oil region includes more than ten fields, including the largest such as Urengoyskoye, Zapolyarnoye, Medvezhye.

The main features of the geological structure. The thickness of the sedimentary cover is more than 4000 m, but the lower part of the section has not been studied by drilling. The Lower-Middle Jurassic deposits are represented by alternating sandstones, siltstones and mudstones with a thickness of 220-445 m. The Upper Jurassic deposits are composed of mudstones with a thickness of 100-150 m. Turonian-Paleogene clays with a thickness of 1000 m serve as a cover.

Huge gas reserves are concentrated in the Valanginian-Cenomanian sandstones with good reservoir properties (porosity 26-34%, permeability up to 3000-6000 mD).

The gases of the Cenomanian deposits consist mainly of 98-99.6% methane. At most fields, condensate is practically absent. The gases of the Valanginian deposit contain a large number of heavy hydrocarbons up to 9.5% and methane up to 88.5%.

The Urengoyskoye field is the largest in the world in terms of gas reserves. It is confined to a gently sloping brachianticlinal fold, the size of which is 95x25 km. The gas reservoir is composed of interbedded sandstones, siltstones, and clays. The total thickness of gas-saturated reservoirs in the arch of the structure is 80-100 m. The porosity of the reservoirs is 20-35%, the permeability is 600-1000 mD.

Test questions:

1. Name the reservoir properties of rocks.

2. What determines the porosity and permeability of rocks?

3. What are the types of porosity and permeability?

4. What is the elemental composition of oil.

5. Talk about physical properties oil.

6. What are the main properties natural gas?

7. Hypotheses of organic and inorganic origin of oil.

8. Characteristics of rocks - collectors.

Russia is one of the world's major oil and gas exporters.

Mineral deposits are mainly located in the central, northern and eastern parts of the country.

History of hydrocarbon production in Russia

In Russia, the development of oil and gas fields has been carried out since the beginning of the 20th century. The first hydrocarbon reserves were discovered in the North Caucasus, on the territory of modern Adygea and Chechnya. These deposits are associated with the oil basins of Kazakhstan and Azerbaijan, which began to be developed after the formation Soviet Union.

In the first half of the 1940s, the USSR needed additional oil and gas to supply the military-industrial complex. The development of oil and gas fields began, located in the Cis-Urals and the Volga region, and then in the north-east of the European part of modern Russia.

In the 1960s, the deposits of Western Siberia began to develop at a rapid pace. Within a few years, a number of large deposits were discovered, including near Urengoy and Yamburg.

It was from here that pipeline systems were subsequently laid, through which hydrocarbon raw materials were delivered not only to the regions of the Soviet Union, but also to Eastern European countries. In the 1980s, the length of the oil and gas transportation system was increased, which made it possible to supply hydrocarbons to the states of Western Europe.

A powerful impetus for the development of the economy of the Far East was the discovery of deposits in the Khabarovsk Territory. Works on oil and gas wells in this region have been carried out since the early 1980s.

Already in the 20th century, the development of deposits in the Barents and Kara Seas began.

Oil and gas regions of the Russian Federation

There are six main oil and gas bearing regions on the territory of Russia:

1. Pacific (Far East).
2. East Siberian.
3. West Siberian.
4. North Caucasian.
5. Volga-Ural.
6. Timano-Pechorsky.

The listed deposits are concentrated not only on the mainland - some of the deposits are located in the shelf zones.

The largest oil and gas fields in Russia

List of largest oil fields Russia is headed by:

1. Priobskoye. It was opened in 1982. It produces about 100 thousand tons of oil daily.
2. Samotlor. Started to be developed in 1965. More than 50 thousand tons of oil are produced per day.
3. Tevlinsko-Russkinskoye. One of the youngest deposits. The daily rate of oil production is 30 thousand tons.
4. Small-balyk. According to 2016 data, up to 30 thousand tons of oil are produced per day.
5. Lyantorskoye, Urengoyskoye and Fedorovskoye. Their development began in the second half of the 1960s. Each of them produces about 25 thousand tons of oil daily.

Gas fields are concentrated on the territory of Siberia. The leader among them is Urengoy. According to the international classification, it belongs to the super giant fields - gas reserves in it exceed 5 trillion cubic meters.

Also, large gas reserves can boast of such fields as:

• Shtokmanovskoye;
• Yamburgskoye;
• Leningradskoye;
• Bovanenkovo;
• Bear;
• Zapolyarnoe;
• Rusanovskoe.

Russian oil and gas companies

Development of the largest oil and gas fields in Russian Federation are run by several companies of different forms of ownership - some are wholly owned by the state (for example, the main player in this market segment is Gazprom), in others controlling stakes are concentrated in the hands of private individuals (Lukoil).

List of major Russian oil and gas companies:

• Gazprom;
• Lukoil;
• Rosneft;
• Tatneft;
• Surgutneftegaz;
• Bashneft;
• TNK-BP;
• Samotlorneftegaz;
• Russneft;
• Yamal LNG.