RU2175941C2 - Method of setting up and operation of underground gas storage in oil-gas condensate deposits - Google Patents

Abstract

FIELD: gas and oil producing industry; operation of underground gas storages on basis of depleted oil and oil-gas condensate deposits. SUBSTANCE: method includes gas injection and extraction through injection wells in pool roof part, and oil withdrawal through oil producing wells from reservoirs of pool bottom part. In this case, zones of maximum oil reserves are singled out and horizontal part of bore of oil producing wells in these zones are located with consideration of zones with the best permeability of reservoir and surface of gas-oil contact. Conditions of maximum distance of any point of bore horizontal part from bottom-holes of the nearest gas injection wells are to be observed. EFFECT: higher efficiency of oil recovery. 2 cl, 2 dwg

Description

 The invention relates to the gas and oil industries and is intended for the operation of underground gas storages (UGS) based on depleted oil and gas condensate fields.

 The closest to the technical essence of this invention is a method of creating and operating UGS facilities in a depleted oil and gas condensate formation, including pumping and taking gas through gas injection wells in the near-water part of the formation and taking oil from oil producing wells from reservoirs of the lower part of the reservoir (USSR, US Pat. No. 1743130 , IPC B 65 G 5/00, dated April 14, 89).

 The disadvantage of this method is that in the specified invention the question of optimizing the placement of gas injection and oil wells in the area of the reservoir, which contributes to an increase in the oil recovery coefficient of the deposits, has not been worked out.

 The task of the invention is to increase the efficiency of oil recovery during the creation and operation of underground gas storage in oil and gas condensate fields.

 The problem is solved due to the fact that in the method of creating and operating UGS facilities in oil and gas condensate fields, including pumping and taking gas through gas injection wells in the near-water part of the reservoir and taking oil from the oil producing wells from reservoirs of the lower part of the reservoir, the zones of the largest oil reserves are allocated and the horizontal part is located the bore of oil wells in these zones, taking into account the zones of the best permeability of the reservoir and the gas-oil contact surface, as well as the conditions for observing the greatest distance of any point of the horizontal part of the trunk from the bottom of the nearest gas injection wells.

 In addition, when placing the horizontal part of the trunk of oil wells, the location of the "old" production wells and the maximum possible drainage of reserves over the area are taken into account.

 In FIG. 1 shows a diagram of the creation and operation of underground gas storage in oil and gas condensate fields.

 In FIG. 2 shows a scheme for opening an oil and gas condensate field with gas injection and oil producing wells.

 The figures show: gas injection wells 1, horizontal sections of oil production wells (Fig. 1), oil production wells (Fig. 2) 2, wells of the “old” stock 3, the zone of the largest residual oil reserves 4, the zone of the best permeability of the reservoir 5, oil circuit 6, gas-oil contact 7.

 When UGS facilities are created in oil and gas condensate fields, gas injection wells (vertical or deviated) are located mainly in the near-water part of the structure and the upper part of the reservoir is opened. Gas is injected and taken through these wells. An artificial gas cap is formed in the oil (oil and gas condensate) reservoir, the reservoir pressure of which increases during the gas injection period. This increases the mutual solubility of gas and oil. Oil becomes more mobile and under pressure of the gas cap is pushed to the bottom of the reservoir, from which it is selected by oil producing wells (mainly horizontal), because this increases the degree of coverage of the oil reservoir. The alternating UGS operation also contributes to an increase in oil mobility. During gas injection, light oil fractions dissolve in the injected gas. Enriched gas is also pushed to the lower part of the reservoir. Oil recovery due to all these processes will increase significantly.

 To increase the efficiency of oil recovery during the creation and operation of UGS facilities, it is necessary to identify the zones of the largest residual oil reserves. To determine the zones of maximum residual oil reserves, a detailed analysis of the previous field operation is carried out and, based on these data, a map of oil production is constructed based on actual data from existing ("old") production wells. According to the constructed map, the influence areas of each well are distinguished and, taking into account the specific oil reserves of each well and the area of these sections, the initial oil reserves of these sections are determined. The difference between the initial oil reserves of each section and its production by wells will make it possible to determine the residual oil reserves of the allocated sections and the distribution of reserves by area. Based on these data, zones of maximum residual oil reserves are distinguished by the area of the reservoir.

 To increase the efficiency of oil recovery, zones of the best permeability of the reservoir are also distinguished. For this, according to the results of the analysis of the previous operation of the field, maps of the specific production rates of individual wells are built, where the zones of maximum production will correspond to the zones of the best permeability of the reservoir.

 When UGS facilities were created in a proven oil (oil and gas condensate) field that was not previously involved in the development, the zones of maximum oil reserves are determined by the specific oil reserves of each well, and the zones of the best permeability of the reservoir are determined by the results of well studies.

 To maximize the coverage of the oil reservoir by the displacement process, oil producing wells are located based on the condition that the greatest distance of any point of the horizontal part of the trunk from the bottom of the nearest gas injection wells is observed and taking into account the surface of the gas-oil contact (GOC).

To maximize oil recovery, the optimal position of the horizontal part of the shafts of oil wells in the area of the reservoir is chosen, given:
- opening of zones with the largest residual oil reserves;
- the location of the maximum possible part of the horizontal section of the trunk in the zones of the best permeability of the reservoir;
- the greatest distance from any point of the horizontal well from the bottom of the nearest gas injection wells;
- location of the surface of the gas-oil contact.

 In addition, it is necessary to consider the location of the trunk between the faces of the "old" production wells and the maximum possible drainage of reserves over the area.

 The method is as follows. An underground gas storage is created at the oil (oil and gas condensate) field, while simultaneously providing an increase in the oil recovery coefficient of the field. To implement the combined process, two categories of wells are drilled: gas injection 1 (vertical or inclined) located in the near-water part of the reservoir, pumping and taking gas into the near-bed part of the reservoir, and oil producing 2 (mainly horizontal) from which oil is produced, with horizontal arrangement parts of the trunk in the lower part of the oil reservoir, where oil is displaced during the creation and operation of the UGS facility.

 According to the results of the analysis of the exploitation (or exploration) of the field, zones of maximum residual (or balance) oil reserves 4 and zones of the best permeability of the reservoir are distinguished 5. Designate the oil contour of the field 6. Determine the surface of the gas-oil contact 7. Given the greatest distance from any points of the horizontal part of the oil producing shafts wells 2 from the bottom of the nearest gas injection wells 1 and the location of the "old" production wells 3 and the maximum possible drainage of reserves by area, placing The horizontal part of the trunk of oil wells in the selected zones of maximum reserves is taken into account, taking into account the zones of the best permeability of the reservoir and the gas-oil contact surface.

 The proposed method for creating and operating an underground gas storage in an oil and gas condensate field by optimizing the location of oil producing wells by the area of the deposit allows us to successfully solve both the problems of increasing the reliability of gas supply and significantly increase the oil recovery coefficient of fields, which is equivalent to discovering new fields without the cost of developing them.

Claims (2)

 1. A method of creating and operating an underground gas storage in oil and gas condensate fields, including pumping and sampling gas through gas injection wells in the near-water part of the deposit and oil extraction by oil producing wells from reservoir reservoirs of the lower part of the reservoir, characterized in that the zones of the largest oil reserves are allocated and horizontal part of the barrel of oil wells in these zones, taking into account the zones of the best permeability of the reservoir and the gas-oil contact surface, as well as compliance with and the greater distance of any point of the horizontal part of the trunk from the bottom of the nearest gas injection wells.  2. The method according to claim 1, characterized in that when placing the horizontal part of the barrel of oil wells, the location of the "old" production wells and the maximum possible drainage of reserves by area are taken into account.

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