A method for designing a gas-drive balanced displacement liquid control production system for a heterogeneous oil reservoir

Abstract

The application provides a non-homogeneous oil reservoir gas drive balanced displacement liquid control production system design method. The non-homogeneous oil reservoir gas drive balanced displacement liquid control production system design method comprises the following steps: obtaining various types of calculation parameters of each injection-production connected region in the plane within a single well group; determining the influence index of various types of calculation parameters on the production allocation scheme design; calculating the liquid production proportion scheme of different production wells in the single well group according to various types of calculation parameters and the influence index; determining the total liquid production speed target of the single well group; and calculating the liquid production speed control scheme of each production well according to the total liquid production speed target of the single well group and the liquid production proportion scheme of each production well in the single well group, so that balanced displacement in each direction of the plane is realized, and the development effect is greatly improved. The application solves the problems of uneven gas sweep in each injection-production direction within the single well group range caused by the reservoir heterogeneity and injection-production well spacing difference in the non-homogeneous oil reservoir gas drive process in the prior art, and poor overall development effect and easy gas channeling.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development technology, and more specifically, to a method for designing a gas-driven equilibrium displacement and fluid control production system for heterogeneous oil reservoirs. Background Technology

[0002] Continental sedimentary reservoirs generally exhibit planar heterogeneity, leading to uneven gas sweep across the reservoir during gas drive, severely impacting development effectiveness. For a typical gas drive development block, a conventional vertical injection-production well group may cover a planar area of ​​several hundred meters. Variations in geological conditions such as sedimentary microfacies and fractures within the well group can result in significant differences in reservoir properties across different areas. Furthermore, due to early development well network design and well abandonment / renewal, the well spacing between injection wells and production wells in different directions within the same well group may also vary. Differences in reservoir properties and well spacing across different planar injection-production interconnected areas significantly affect the sweep efficiency of injected gas within the well group, potentially causing severe uneven gas sweep across different injection-production directions and impacting overall sweep efficiency. In some directions, gas sweep is rapid, leading to rapid gas production in those directions, increasing not only ineffective gas circulation but also the risk of gas channeling; in other directions, gas sweep is slow and inefficient, resulting in low reservoir utilization. Therefore, effectively promoting balanced displacement across all directions in planar heterogeneous reservoirs is crucial.

[0003] To achieve the above goals, there is currently a lack of low-cost and effective reservoir engineering design methods. At present, oilfield sites typically allocate production wells simply based on the overall production target of the development block. For adjacent areas, especially within the same well group, production wells often use the same or similar production rates. This conventional production allocation scheme is simple to operate, convenient for field management, and can achieve the expected production in the early stages of development. However, due to the existence of planar heterogeneity, as development progresses, the injected gas gradually becomes unevenly distributed in all directions, severely affecting the development results in the mid-to-late stages.

[0004] Some scholars have proposed two solutions, but both have certain problems. The first solution is to adopt a pressure-controlled production mode, which involves controlling the production pressure of different production wells within the well group, resulting in different injection-production pressure differentials in different injection-production directions, thereby promoting balanced displacement. However, this method has two drawbacks: First, the imperfect field technology makes implementation extremely difficult. Currently, most oil wells rely on mechanical pumping for production, and achieving pressure-controlled production in mechanical pumping wells is extremely difficult in terms of technology. Second, the design of related pressure control schemes is difficult. Since the formation pressure system continuously changes during development, dynamic pressure control schemes need to be matched to different development time points, and there is a lack of corresponding design methods. The second solution is to adopt a periodic injection-production well switching mode, that is, to selectively open or close injection wells or production wells during the development cycle in order to change the seepage channel and improve the impact effect. However, this method also has two major drawbacks: First, it will seriously sacrifice the working time of injection and production wells. Reduced gas injection time will affect the formation energy replenishment efficiency, and reduced oil production time will affect the stage production. Second, this method will significantly increase the workload and construction costs on site, and frequent well opening and closing will also cause process problems.

[0005] Therefore, in the existing technology, the gas wave in the plane in different injection and production directions is uneven due to the difference in reservoir properties and injection-production well distance in different areas of the well group during the gas drive process of heterogeneous reservoirs. This makes it impossible to reach each production well synchronously, resulting in a large amount of gas circulating ineffectively, which leads to poor overall development effect and easy gas channeling. Moreover, there is a lack of low-cost and effective reservoir engineering design methods to solve this problem. Summary of the Invention

[0006] The main objective of this invention is to provide a design method for a gas-driven balanced displacement and fluid control production system in heterogeneous reservoirs, in order to solve the problem of uneven gas spread in different injection and production directions caused by differences in reservoir properties and injection-production well spacing during gas-driven processes in heterogeneous reservoirs in the prior art.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for designing a gas-driven, balanced displacement, and fluid-controlled production system for heterogeneous reservoirs is provided, comprising: obtaining various calculation parameters of each injection-production interconnected region within a single well group; determining the influence index of each calculation parameter on the production allocation scheme design; calculating a reasonable fluid production ratio scheme for production wells in different injection-production directions (locations) within the single well group based on the various calculation parameters and their influence indices in each region; and determining the target total fluid production rate for the single well group. Based on the production ratio of each production well within a single well group and the target total production rate of the single well group. A reasonable production rate control scheme for each production well is calculated, thereby forming a fluid control production system with balanced displacement as the goal.

[0008] Furthermore, the calculation parameters include: effective sand body thickness H, porosity Permeability K and injection-production well spacing L.

[0009] Furthermore, the influencing indices include: the influencing index of effective sand body thickness. Porosity Influence Index Penetration rate impact index Influence index of injection and production well spacing .

[0010] Furthermore, within the range of conventional heterogeneity (where the effective thickness difference between different injection-production interconnected zones does not exceed 3 within a single well group), the sand body effective thickness influence index... The value is 1.0.

[0011] Furthermore, within the range of typical heterogeneity (where the porosity difference between different injection-production interconnected zones does not exceed 3 within a single well group), the porosity influence index... The value is 1.0.

[0012] Furthermore, within the range of typical heterogeneity (where the permeability difference between different injection-production interconnected zones does not exceed 3 within a single well group), the permeability influence index... The value is 0.5.

[0013] Furthermore, when the difference in injection well spacing between injection wells and production wells in different directions within a single well group does not exceed 3, the injection-production well spacing influence index... The value is 2.0.

[0014] Furthermore, the reasonable production ratio of the i-th producing well within a single well group is: .

[0015] Furthermore, a reasonable production rate control scheme for the i-th production well. satisfy: .

[0016] Furthermore, the single-well group is a conventional vertical well development well group with 1 injection and N production.

[0017] Applying the technical solution of this embodiment, various calculation parameters of each injection-production interconnection zone in the plane within a single well group are obtained. Combined with their influence indices, the reasonable production ratio of each production well in the single well group, with the goal of achieving balanced displacement, is calculated. Then, based on the target total production rate of the single well group... This method allocates production to each production well proportionally, thereby obtaining a reasonable production rate control scheme for each production well. For the reservoir range covered by a single well group, this method quantifies the impact of reservoir properties and well spacing differences between different injection-production interconnected areas within the well group on the gas sweep uniformity. Different production rate control schemes are designed for production wells in different interconnected areas to guide the injected gas to advance uniformly to different production wells, ensuring it reaches each production well as synchronously as possible. This effectively alleviates problems such as uneven gas sweep, high ineffective circulation rate, low overall recovery, and easy gas channeling caused by reservoir heterogeneity, thus improving the overall gas drive development effect. Therefore, the gas drive balanced displacement controlled fluid production system design method for heterogeneous reservoirs in this application effectively solves the problem of uneven gas sweep in different injection-production directions in the plane due to differences in reservoir properties and well spacing during gas drive in heterogeneous reservoirs, resulting in poor overall development effect and easy gas channeling. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A schematic diagram of a planar heterogeneous reservoir injection-production well network development according to a specific embodiment of this application is shown (where the dashed box represents the range of a single well group, which contains 1 injection well and 2 production wells, i.e. 2 injection-production connected areas).

[0020] Figure 2 This invention illustrates a model of the sand body effective thickness heterogeneity in a specific embodiment of the present application for analyzing the wave effect of injected gas in response to the planar heterogeneity of the sand body effective thickness.

[0021] Figure 3 This paper illustrates a comparison of the injected gas sweep efficiency of different schemes for the planar heterogeneity of the effective thickness of the sand body in a specific embodiment of this application (the different schemes shown in the figure are the overall CO2 sweep efficiency concentration field when the production well on one side of the well group just sees gas, and the unit in the figure is kilomol / m³).

[0022] Figure 4 This application illustrates a porosity heterogeneity model for analyzing the ripple effect of injected gas in response to porosity planar heterogeneity in a specific embodiment of the present application.

[0023] Figure 5 This paper illustrates a comparison of the injected gas sweep efficiency under different schemes for porosity planar heterogeneity in a specific embodiment of this application (the different schemes shown in the figure are all overall CO2 sweep efficiency field diagrams when the production wells on one side of the well group just see gas, and the units in the figure are kilomol / m³).

[0024] Figure 6 This application illustrates a permeability heterogeneity model for analyzing the sweeping effect of injected gas in a specific embodiment of permeability plane heterogeneity.

[0025] Figure 7 This paper illustrates a comparison of the injected gas sweep efficiency of different schemes for permeability plane heterogeneity in a specific embodiment of this application (the different schemes shown in the figure are all overall CO2 sweep efficiency field diagrams when the production wells on one side of the well group just see gas, and the units in the figure are kilomol / m³).

[0026] Figure 8 This application illustrates a specific embodiment of the injection-production well distance difference model for analyzing the injected gas sweep effect when performing injection-production well distance difference analysis between injection wells and production wells in different directions;

[0027] Figure 9 This paper illustrates a comparison of the injected gas sweep effect obtained by using different schemes for the difference between injection and production wells in a specific embodiment of this application (the different schemes shown in the figure are all overall CO2 sweep concentration field diagrams when the production well on one side of the well group just sees gas, and the unit in the figure is kilomol / m³).

[0028] Figure 10 A flowchart illustrating a specific embodiment of the method for designing a gas-drive equilibrium displacement and controlled-fluid production system for heterogeneous oil reservoirs is shown. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0032] To address the problems in existing technologies where uneven gas flow in different directions within a well group due to differences in reservoir properties and injection-production well spacing during gas drive in heterogeneous reservoirs leads to gas fronts failing to reach production wells in each direction synchronously, resulting in a large amount of ineffective gas circulation, poor overall development performance, and susceptibility to gas channeling, this application provides a design method for a balanced displacement and controlled fluid production system in gas drive for heterogeneous reservoirs.

[0033] like Figure 10 As shown, the design method for a gas-driven, balanced displacement, and fluid-controlled production system in heterogeneous reservoirs in this application includes: obtaining various calculation parameters for each injection-production interconnected region within a single well group; determining the influence index of each calculation parameter on the production allocation scheme design; calculating a reasonable fluid production ratio scheme for each injection-production direction (location) production well within the single well group based on the balanced displacement target; and determining the total fluid production rate target for the single well group. Based on the production ratio of each production well within a single well group and the target total production rate of the single well group. A reasonable production rate control scheme for each production well was calculated.

[0034] The “reasonable” scheme in the above-mentioned “reasonable liquid production ratio scheme” and “reasonable liquid production rate control scheme” refers to a scheme designed to achieve the goal of balanced displacement.

[0035] By acquiring various calculation parameters of each injection-production interconnected area within a single well group and combining them with their influence indices, the reasonable production ratio of each production well within the single well group is calculated. Then, based on the total production rate target of the single well group, production is allocated to each production well proportionally, thereby obtaining a reasonable production rate control scheme for each production well. This method, targeting the reservoir range covered by the single well group, quantifies the impact of reservoir properties and well spacing differences between different injection-production interconnected areas within the well group on the gas sweep uniformity within the well group. Different production rate control schemes are designed for production wells in different interconnected areas to guide the injected gas to advance uniformly to different production wells, ensuring that it reaches each production well as synchronously as possible. This effectively alleviates problems such as uneven gas sweep, high ineffective circulation rate, low overall recovery rate, and easy gas channeling caused by reservoir planar heterogeneity, thus improving the overall development effect of gas drive. Therefore, the gas drive balanced displacement and fluid control production system design method for heterogeneous reservoirs in this application effectively solves the problems of uneven gas distribution in different injection and production directions, poor overall development effect, and easy gas channeling caused by differences in reservoir properties and injection-production well spacing during the gas drive process of heterogeneous reservoirs in the prior art.

[0036] Specifically, the calculation parameters include: effective sand body thickness H, porosity Permeability K and injection-production well spacing L.

[0037] Specifically, the indices include: the effective thickness of the sand body influence index. Porosity Influence Index Penetration rate impact index Influence index of injection and production well spacing .

[0038] Specifically, within the range of conventional heterogeneity (within a single well group, the reservoir property difference between different injection-production interconnected areas does not exceed 3, and the difference in injection-production well spacing in different directions does not exceed 3), the sand body effective thickness influence index The possible value is 1.0. Porosity Influence Index The possible value is 1.0. Penetration rate influence index. A possible value is 0.5. Injection-production well spacing influence index. A value of 2.0 is acceptable. In special cases of strong heterogeneity (high grade difference), using the above value to calculate and design production allocation schemes can also achieve a significant effect in promoting balanced displacement. When the grade difference is too large, the influence index can be further optimized and adjusted through numerical simulation methods.

[0039] Specifically, the reasonable production ratio of the i-th producing well within a single well group is: .

[0040] Specifically, the reasonable fluid production rate control scheme for the i-th production well. satisfy: .

[0041] Specifically, the single-well group is a conventional vertical well development well group with 1 injection and N production.

[0042] This application comprehensively considers the differences in reservoir properties such as effective sand body thickness, porosity, and permeability between different injection-production interconnected areas within a single well group, as well as the differences in injection-production well spacing between injection wells and different production wells. It provides a calculation method for rationally designing production rate control schemes for different production wells within a well group, aiming to promote uniform planar sweep of injected gas, synchronous arrival at each production well, and achieve balanced planar displacement. This algorithm is convenient and effective, and can quickly calculate reasonable production allocation schemes for production wells at different locations within the well group. In the embodiments, this innovative method was applied and tested based on typical block data, and its effectiveness was verified through numerical simulation. The results show that the production allocation scheme calculated using this algorithm can significantly improve the uniformity of injected gas sweep in planar heterogeneous reservoirs, promote the synchronous arrival of injected gas at different production wells within the well group, achieve balanced planar displacement, significantly increase gas sweep volume, reduce ineffective injected gas circulation, reduce gas channeling risk, and improve overall development efficiency.

[0043] like Figure 1As shown, taking a fluvial sedimentary planar heterogeneous reservoir with a row-shaped injection-production well network (1 injection and 2 production wells within a single well group) as an example, within the coverage area of ​​a certain injection-production well group (within the black dashed box), variations in sedimentary microfacies may exist in different injection-production displacement directions (left and right), leading to differences in reservoir properties, such as permeability (K) and porosity (K). The effective thickness of the sand body (H), etc. Furthermore, due to early development well pattern design, abandonment and replacement of injection and production wells, the well spacing (L) in different directions may also vary. Differences in reservoir properties and well spacing have a significant impact on the sweep efficiency of gas drive.

[0044] To achieve balanced displacement and promote the synchronous arrival of injected gas at each production well, it is necessary to control the leading-edge propagation velocity of the injected gas in different directions in the plane. This application, through the rational design and control of the production velocity of different production wells within the well group, indirectly affects the propagation of the injected gas towards different production wells via pressure transmission. The entire process of gas injection from the reservoir to the production well is an unsteady displacement process, and the reservoir pressure at different locations within the well group area is dynamically changing. Factors affecting the leading-edge propagation of the injected gas are analyzed from both the injection and production ends. Among them: effective sand body thickness (H) and porosity (H) The cross-sectional area affecting flow is as follows: the larger the effective thickness and porosity of the sand body, the larger the flow cross-sectional area. Under controlled liquid production mode, the slower the leading edge advance speed is at the same flow rate. Permeability (K) directly affects the fluid advance speed. Although controlled liquid production mode is used at the production wellhead and the flow speed remains stable, the gas advance speed at the injection wellhead is affected by permeability before pressure feedback from the production wellhead. The higher the permeability, the faster the gas advance in the initial stage of injection. The injection-production well spacing (L) in different directions within the well group directly affects the differentiated design of the gas leading edge advance speed in different directions. The larger the injection-production well spacing in a certain direction, the faster the required gas leading edge advance speed in that direction. Therefore, based on the above-mentioned reservoir properties and the effects caused by the differences in injection-production well spacing, if we want to promote balanced displacement in all directions in the plane and make the displacement leading edge reach each production well as synchronously as possible, we need to design differentiated production rate control schemes for different production wells.

[0045] Based on the above analysis, considering the effective thickness (H) and porosity of the sand body... Based on the factors of permeability (K) and injection-production well spacing (L), an innovative calculation method was established for a reasonable fluid production rate control scheme for production wells at different locations within a single well group. For example... Figure 1 As shown, taking a row-shaped injection-production well network as an example, a single well group contains 1 injection well and 2 production wells. Assume the average effective sand body thickness in the reservoir area between the injection well and the production well on the left is H1, and the average porosity is... 1. The average permeability is K1, the injection-production well spacing is L1, the average effective sand body thickness in the reservoir region between the injection well and the right-side production well is H2, and the average porosity is [missing information]. 2. Given an average permeability of K2 and an injection-production well spacing of L2, to promote balanced displacement and ensure that the injected gas reaches the production wells on both sides as simultaneously as possible, the reasonable production rates of the two production wells must satisfy the following:

[0046]

[0047] In the formula, and These are the design values ​​for the reasonable fluid production rate of the left and right production wells in the well group, respectively. and These represent the average effective thickness of the sand body in the area connecting the injection well and the left and right production wells within the well group. and These represent the average porosity of the area connecting the injection well and the left and right production wells within the well group. and These represent the average permeability of the area connecting the injection well and the left and right production wells within the well group. and These refer to the well distances between the injection well and the left and right production wells within the well group. , , and The influence indices for the aforementioned parameters are used to characterize the degree of influence of effective sand body thickness, porosity, permeability, and differences in injection-production well spacing on the differences in reasonable production rates of production wells in different directions. A larger influence index indicates a greater impact of the parameter difference on the production allocation scheme design. The influence indices for different parameters are mainly affected by the heterogeneity intensity of that parameter within the well group (including the degree of difference in injection-production well spacing), and can be quantified using grade differences (i.e., the ratio of the maximum to the minimum value). Under normal circumstances, where the grade difference does not exceed 3... , , and Values ​​of 1.0, 1.0, 0.5, and 2.0 can be used to calculate production allocation schemes that can basically achieve balanced displacement in all directions of the plane. In special cases with large grade differences, using the above values ​​to calculate and design production allocation schemes can also achieve a significant effect in promoting balanced displacement. When the grade difference is too large, the influence index can be further optimized and adjusted through numerical simulation methods.

[0048] When the overall production target of a single well group (i.e., the overall fluid production rate target of the well group: Once determined, the reasonable production rate design values ​​(i.e., reasonable production rate control scheme) of the production wells on the left and right sides of the well group can be calculated according to the following formula:

[0049]

[0050]

[0051] The above formula is based on a row-shaped injection-production well network (1 injection well and 2 production wells in a single well group). Extending the formula and algorithm, it can be applied to different well network types. Assuming a single well group contains 1 injection well and N production wells, the area between the injection well and the N production wells can be divided into N reservoir regions (i.e., planar injection-production connectivity areas). Assuming the average effective sand body thickness of the reservoir region between the injection well and the i-th production well in the well group is... The average porosity is Average penetration rate Well spacing is Then, the reasonable production rate control scheme for the i-th producing well in this well group can be calculated by the following formula: .

[0052] In one specific embodiment of this application, technical application tests were conducted based on the basic parameters of a typical reservoir block in the Jilin Oilfield CO2 flooding demonstration area to verify the effectiveness of the balanced displacement and fluid control production system design method innovatively proposed in this invention. The target reservoir in Block H of the D oilfield has a mid-depth of 2150m, a formation temperature of 97.3℃, an initial formation pressure of 23MPa, an average permeability of 5md, an average porosity of 12%, an average effective thickness of 5m, a row-shaped well network, an injection-production well spacing of 200-300m, and a target daily gas injection of 10t and a target daily fluid production of 15m³ per well group. 3 . Reference Figure 1 The schematic diagram of the development of a planar heterogeneous reservoir with a row of injection-production wells is shown. Applying the calculation method innovatively proposed in this application, the design of a reasonable production rate control scheme for each production well in the well group is optimized for different scenarios, such as the effective thickness, porosity, permeability, and planar heterogeneity of sand bodies in different injection-production interconnected areas within a single well group, as well as the differences in injection-production well spacing. This results in a reasonable production allocation scheme for different scenarios. Then, based on the typical geological reservoirs, well network spacing, and injection-production parameters of the above-mentioned block, a numerical model of the CO2 flooding mechanism is established. Numerical simulations are performed on the production allocation scheme designed by the innovative method proposed in this application and the conventional production allocation scheme. The CO2 flooding sweep effect of the scheme designed by the method of this application and the conventional scheme are compared, thereby further verifying the effectiveness of the design method of the reasonable production rate control scheme (balanced displacement control production system) based on the balanced displacement target proposed in this application.

[0053] (1) Planar heterogeneity of effective thickness of sand body

[0054] by Figure 1 As shown for reference, the average porosity of the left and right injection-production connected regions is set. , Both are 12%, with an average penetration rate. , Both are 5md, injection-production well spacing , Both are 250m, and the average effective thickness of the sand body in the left injection-production connected zone is... The average effective thickness of the sand body in the injection-production connection zone on the right is 6m. The target daily fluid production for a single well group is 4m. 15m 3 The model is as follows: Figure 2 As shown.

[0055] Under conventional methods, the two producing wells within a single well group typically employ the same production rate (daily production) control scheme, i.e. ; .

[0056] By applying the design method proposed in this application and substituting various calculation parameters into the formulas described above, a reasonable production rate (daily production) control scheme for the left and right production wells can be obtained. ; .

[0057] Numerical simulations were used to predict the gas-driven sweep effects of the two schemes described above. The overall CO2 sweep effect when gas is encountered from one production well within the well group was compared under different schemes. The results are as follows: Figure 3 As shown.

[0058] Numerical simulation results show that if there are certain differences in the effective thickness of sand bodies in the reservoirs of different injection-production interconnected areas within the well group, the conventional production allocation scheme will lead to severe uneven gas sweep. When the production well on the right side reaches gas, the gas sweep in the left side area is still low, and the gas front is still a certain distance from the production well. However, the production rate control scheme for different production wells designed by the method described in this application can achieve significant improvement, basically realizing that the injected gas reaches the production wells on the left and right sides synchronously, effectively promoting planar balanced displacement.

[0059] (2) Porosity planar heterogeneity

[0060] by Figure 1 As shown for reference, the average effective thickness of the sand body in the left and right injection-production connected regions is set. , All are 5m, with an average permeability , Both are 5md, injection-production well spacing , Both are 250m, and the average porosity of the injection-production connected zone on the left is... The average porosity of the injection-production connected region on the right side is 13%. The overall daily fluid production target for a single well group is 11%. 15m 3 The model is as follows: Figure 4 As shown.

[0061] Under conventional methods, the two producing wells within a single well group typically employ the same production rate (daily production) control scheme, i.e. ; .

[0062] By applying the design method proposed in this application and substituting various calculation parameters into the formulas described above, a reasonable production rate (daily production) control scheme for the left and right production wells can be obtained. ; .

[0063] Numerical simulations were used to predict the gas-driven sweep effects of the two schemes described above. The overall CO2 sweep effect when gas is encountered from one production well within the well group was compared under different schemes. The results are as follows: Figure 5 As shown.

[0064] Numerical simulation results show that if there are certain porosity differences in reservoirs in different injection-production interconnected areas within the well group, the conventional production allocation scheme will lead to severe uneven gas sweep. When gas is encountered in the right production well, the gas sweep in the left area is relatively low, and the gas front is still some distance away from the production well. However, the production rate control scheme for different production wells designed by the method described in this application can achieve significant improvement, basically realizing that the injected gas reaches the left and right production wells synchronously, effectively promoting planar balanced displacement.

[0065] (3) Permeability plane heterogeneity

[0066] by Figure 1 As shown for reference, the average effective thickness of the sand body in the left and right injection-production connected regions is set. , All are 5m, with an average porosity of , Both are 12%, injection-production well spacing , Both are 250m, and the average permeability of the injection-production connection zone on the left is... The average permeability of the injection-production connection zone on the right side is 6md. The target daily fluid production for a single well group is 4md. 15m 3 The model is as follows: Figure 6 As shown.

[0067] Under conventional methods, the two producing wells within a single well group typically employ the same production rate (daily production) control scheme, i.e. ; .

[0068] By applying the design method proposed in this application and substituting various calculation parameters into the formula described above, the reasonable production rate (daily production) control scheme for the left and right production wells can be calculated as follows: ; .

[0069] Numerical simulations were used to predict the gas-driven sweep effects of the two schemes described above. The overall CO2 sweep effect when gas is encountered from one production well within the well group was compared under different schemes. The results are as follows: Figure 7 As shown.

[0070] Numerical simulation results show that if there are certain permeability differences in reservoirs in different injection-production interconnected areas within the well group, the conventional production allocation scheme will lead to severe uneven gas sweep. When the production well on the left side reaches gas, the gas front in the right side area is still some distance away from the production well. However, the production rate control scheme for different production wells designed using the method described in this application can achieve significant improvement, basically realizing that the injected gas reaches the production wells on both the left and right sides synchronously, effectively promoting planar balanced displacement.

[0071] (4) Differences in injection and production well spacing in different directions

[0072] by Figure 1 As shown for reference, the average effective thickness of the sand body in the left and right injection-production connected regions is set. , All are 5m, with an average porosity of , Both are 12%, with an average penetration rate. Both are 5md, and the well distance between the injection well and the production well on the left is... The distance between the well and the production well on the right is 100m. The target daily fluid production for a single well group is 150m. 15m 3 The model is as follows: Figure 8 As shown.

[0073] Under this scheme, the two production wells within a single well group typically employ the same production rate (daily production) control scheme, i.e. ; .

[0074] By applying the design method proposed in this application and substituting various calculation parameters into the formulas described above, a reasonable production rate (daily production) control scheme for the left and right production wells can be obtained. ; .

[0075] Numerical simulations were used to predict the gas-driven sweep effects of the two schemes described above. The overall CO2 sweep effect when gas is encountered from one production well within the well group was compared under different schemes. The results are as follows: Figure 9 As shown.

[0076] Numerical simulation results show that if there are differences in the injection and production well spacing in different directions within the well group, the conventional production allocation scheme will lead to severe uneven gas sweep. When the production well on the left side reaches gas, the gas sweep in the right side area is very low, and the gas front is still a large distance from the production well. However, the production rate control scheme for different production wells designed by the method described in this application can achieve significant improvement, basically realizing that the injected gas reaches the production wells on the left and right sides synchronously, effectively promoting planar balanced displacement.

[0077] Figure 3 , 5 7 and 9 represent the comparison of the swirl effect of injected gas obtained under different analysis scenarios and using different production schemes. Figure 3 , 5 The different schemes shown in 7 and 9 are all overall CO2 sweep concentration field diagrams when the production well on one side of the well group has just encountered gas. The CO2 concentration in the above diagrams is in kilomol / m³.

[0078] Based on the above analysis and description, it can be seen that the embodiments of the present invention achieve the following technical effects: Addressing the problems of gas drive waves and easy gas channeling in heterogeneous planar reservoirs of terrestrial sedimentary formations, the present invention innovatively proposes an optimized design method and process for controlled fluid production regimes, aiming to achieve planar balanced displacement. This method comprehensively considers the differences in reservoir properties such as effective thickness, porosity, and permeability of sand bodies in different injection-production interconnected areas within a single well group, as well as the differences in injection-production well spacing in different directions. It establishes a calculation method for a reasonable fluid production rate control scheme for production wells at different locations within the designed well group. This method is convenient and effective, and can quickly calculate a reasonable production allocation scheme for different production wells within the well group, thereby forming a balanced displacement controlled fluid production regime. In the embodiments, the method was applied and tested based on typical block data, and its effect was verified by numerical simulation. The results show that the production allocation scheme calculated by the algorithm can significantly improve the uniformity of gas sweep in planar heterogeneous reservoirs, promote the synchronous arrival of gas injected from injection wells in different locations within the well group, achieve balanced displacement, significantly improve gas sweep efficiency, reduce ineffective gas circulation, reduce the risk of gas channeling, and improve the overall development effect.

[0079] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0080] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0081] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for designing a gas-drive equilibrium displacement controlled-fluid production system for heterogeneous oil reservoirs, characterized in that, include: Obtain various calculation parameters for each injection-production connectivity zone in the plane within a single well group; Determine the impact index of the various calculation parameters on the production allocation scheme design; Calculate the production ratio of each production well within the single well group; Determine the total production rate target for the single well group. ; Based on the production ratio scheme of each production well in the single well group and the target total production rate of the single well group. The production rate control scheme for each production well was calculated.

2. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 1, characterized in that, The calculation parameters include: effective sand body thickness H, porosity Permeability K and injection-production well spacing L.

3. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 2, characterized in that, The indices include: the effective thickness of the sand body indices. Porosity Influence Index Penetration rate impact index Influence index of injection-production well spacing .

4. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 3, characterized in that, The effect index of effective thickness of sand body The value is 1.

0.

5. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 3, characterized in that, The porosity influence index The value is 1.

0.

6. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 3, characterized in that, The penetration rate affects the index The value is 0.

5.

7. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 3, characterized in that, The influence index of injection and production well spacing The value is 2.

0.

8. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to any one of claims 3 to 7, characterized in that, The production fluid percentage of the i-th producing well in a single well group is: Where N is the total number of production wells in a single well group with 1 injection and N extraction.

9. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to claim 8, characterized in that, The production rate control scheme for the i-th production well for: .

10. The method for designing a gas-drive equilibrium displacement and fluid control production system for heterogeneous oil reservoirs according to any one of claims 1 to 7, characterized in that, The single well group is a vertical well development well group with 1 injection and N production.

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