An injection-production method with optimized interlayer combination

Abstract

The present invention relates to an injection-production method with optimized interlayer combination. The method includes: obtaining oil saturation data and permeability data of a target reservoir; performing cluster analysis on the oil saturation data, and dividing the target reservoir into at least two oil saturation combination regions according to the results of the cluster analysis; each oil saturation combination region corresponds to an oil saturation interval; determining the number of levels of the permeability ratio of the target reservoir according to the permeability data; simulating the recovery factor corresponding to each permeability ratio under each oil saturation interval in a three-dimensional geological model, finding out the mutation permeability ratio with the recovery factor decline exceeding the set threshold, taking the upper level of the mutation permeability ratio as the critical permeability ratio, adopting the separate injection method when exceeding the critical permeability ratio, and adopting the combined injection method when not exceeding the critical permeability ratio; determining the injection-production method of the current region according to the oil saturation interval and the permeability ratio of the current region. The present invention guides reservoir development and improves the recovery factor.

Description

Technical Field

[0001] The invention relates to an interlayer optimized combination injection and production method, belonging to the technical field of oil and gas reservoir water drive development. Background Art

[0002] Most oil and gas reservoirs in certain areas have varying degrees of heterogeneity, which can easily lead to uneven water absorption during water injection development. Some layers even do not absorb water, resulting in serious imbalance in interlayer production. It is necessary to use an interlayer optimization combination mining method for water injection development. At this stage, the interlayer optimization combination research is mainly aimed at static indicators, and the optimized combination is determined according to the interlayer permeability difference to subdivide the injection and production.

[0003] However, after water injection development, most of the old water-driven oil fields have now entered the high water-cut development stage, and the heterogeneity is even stronger. The method of determining the optimized combination of injection and production based solely on the interlayer permeability difference can no longer meet the needs. Therefore, some people have proposed an injection allocation scheme combined with multi-parameter design. For example, the Chinese invention patent application document with application publication number CN 104234673 A discloses a layered injection allocation method for multi-layer reservoirs considering interlayer interference. The method first finds out the influence of permeability difference on water absorption index, water content on water absorption index, and viscosity difference on water absorption index through experiments, and obtains the interference degree of different permeability differences, water absorption index coefficient related to water content, and interference degree of different viscosity differences; then, different injection allocation schemes are set, and the injection amount of different injection allocation schemes is calculated based on the interference degree of different permeability differences, water absorption index coefficient related to water content, and interference degree of different viscosity differences; finally, the scheme with the largest injection amount is selected as the optimal injection allocation scheme.

[0004] However, the above injection method is computationally complex, and the calculation of various interference levels and coefficients obtained based on the experiment is not accurate, resulting in inaccurate injection scheme design and reduced mining efficiency. Summary of the Invention

[0005] The purpose of this application is to provide an injection-production method with optimized interlayer combination, so as to solve the problem of inaccurate injection and production scheme design in the prior art and reduced production rate.

[0006] To achieve the above objectives, the present application proposes a technical solution for an injection-production method with optimized interlayer combination, which includes the following steps:

[0007] 1) Construct a basic 3D geological model based on the geological parameters of the target reservoir, including the depth, type, thickness, rhythmicity, and facies of each stratum;

[0008] 2) Obtain the oil saturation data of the target reservoir; the oil saturation data is the oil saturation of each formation in each single well of the target reservoir; perform cluster analysis on the oil saturation data, and divide the target reservoir into at least two oil saturation combination regions according to the cluster analysis results; each oil saturation combination region corresponds to an oil saturation interval; determine the designed oil saturation values corresponding to each formation in the simulated three-dimensional geological model according to the oil saturation interval;

[0009] 3) Obtain the permeability data of the target reservoir; the permeability data includes the permeability of each formation in each single well of the target reservoir; determine the number of levels of the permeability ratio difference of the target reservoir according to the permeability data; according to the corresponding relationship between the permeability data and each formation in the basic three-dimensional geological model, obtain the designed permeability value of a certain set formation in the basic three-dimensional geological model, and determine the designed permeability values corresponding to each formation in the simulated three-dimensional geological model according to the determined number of levels of the permeability ratio difference and the designed permeability value of the set formation;

[0010] 4) Input the designed oil saturation values corresponding to each formation obtained in step 2) and the designed permeability values corresponding to each formation obtained in step 3) into the basic three-dimensional geological model to obtain the simulated three-dimensional geological model under each oil saturation interval and each permeability ratio difference;

[0011] 5) Simulate the recovery rate corresponding to each permeability ratio difference under each oil saturation interval in the simulated three-dimensional geological model, find out the sudden change permeability ratio difference whose recovery rate decline exceeds the set threshold, and take the upper-level permeability ratio difference of the sudden change permeability ratio difference as the critical permeability ratio difference for combined injection / separate injection. When the critical permeability ratio difference is exceeded, separate injection is adopted, and when the critical permeability ratio difference is not exceeded, combined injection is adopted;

[0012] 6) Determine the injection-production method for the current area according to the oil saturation interval and permeability ratio difference of the current area, and then complete the injection-production.

[0013] The beneficial effects of the technical solution of the injection-production method for interlayer optimization combination of the present invention are as follows: The present invention performs cluster analysis on the oil saturation data of the target reservoir to obtain the oil saturation intervals representing different optimization combination regions, and then combines the oil saturation intervals and the permeability ratio difference to simulate the recovery rate of each permeability ratio difference under each oil saturation interval, and determines the combined injection-production method according to the recovery rate. The present invention determines the injection-production method for interlayer optimization combination by combining the oil saturation and the permeability ratio difference, guides the reservoir development, improves the recovery rate, and further improves the water drive utilization degree and water drive swept volume of the layers in high water cut reservoirs.

[0014] Further, in order to improve the production rate of combined injection and production, in step 2), the target oil reservoir is divided into three combined oil saturation regions; the oil saturation range of the first combined oil saturation region is [x1, x2], where x1 < x2; the oil saturation range of the second combined oil saturation region is [x3, x4], where x3 < x4; the oil saturation range of the third combined oil saturation region is [x5, x6], where x5 < x6; x4 < x1; x3 ≤ x5 < x4; x1 < x6 < x2.

[0015] Further, in step 3), the process of obtaining the designed permeability value of a certain set formation in the basic three-dimensional geological model is as follows: find all the actual permeability values corresponding to each depth in the set formation of the basic three-dimensional geological model from the permeability data, take the average of all the actual permeability values corresponding to each depth to obtain the permeability values of each depth of the set formation in the basic three-dimensional geological model, and then take the average of the permeability values of each depth of the set formation to obtain the designed permeability value of the set formation.

[0016] Further, the oil saturation data is obtained by core analysis and well logging interpretation calculation.

[0017] Further, the permeability data is obtained according to well logging data.

[0018] Further, the clustering analysis algorithm adopts the K-Means algorithm.

[0019] Further, the grid step size in the basic three-dimensional geological model is 5m × 5m × 0.25m, and the total number of grids is 180 × 150 × 20.

[0020] Further, the number of grades of the permeability gradient of the target oil reservoir is determined according to the maximum permeability and the minimum permeability in the permeability data. Description of the Drawings

[0021] Figure 1 is a flowchart of the injection-production method for interlayer optimization combination of the present invention;

[0022] Figure 2 is a scatter plot of the oil saturation of the present invention;

[0023] Figure 3a is a grid three-dimensional view of the virtual saturation model of the present invention;

[0024] Figure 3b is a grid plan view of the virtual saturation model of the present invention;

[0025] Figure 4a is a model diagram of the oil reservoir with high-low oil saturation combination of the present invention when the permeability gradient is 1;

[0026] Figure 4b It is the model diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 3;

[0027] Figure 4c It is the model diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 5;

[0028] Figure 4d It is the model diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 7;

[0029] Figure 5a It is the cumulative oil production comparison curve of the reservoir with low-low oil saturation combination of the present invention under different permeability ratios;

[0030] Figure 5b It is the cumulative oil production comparison curve of the reservoir with high-low oil saturation combination of the present invention under different permeability ratios;

[0031] Figure 5c It is the cumulative oil production comparison curve of the reservoir with high-high oil saturation combination of the present invention under different permeability ratios;

[0032] Figure 6a It is the oil displacement effect diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 3;

[0033] Figure 6b It is the oil displacement effect diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 5;

[0034] Figure 6c It is the oil displacement effect diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 6; [[ID=!35]]

[0035] Figure 6d It is the oil displacement effect diagram of the reservoir with high-low oil saturation combination of the present invention when the permeability ratio is 7;

[0036] Figure 7a It is the recovery ratio comparison diagram of the reservoir with low-low oil saturation combination of the present invention under different permeability ratios;

[0037] Figure 7b It is the recovery ratio comparison diagram of the reservoir with high-low oil saturation combination of the present invention under different permeability ratios;

[0038] Figure 7c It is the recovery ratio comparison diagram of the reservoir with high-high oil saturation combination of the present invention under different permeability ratios. Specific embodiments

[0039] Example of the injection-production method for interlayer optimization combination:

[0040] The main concept of the present invention is that through the analysis of reservoirs with higher water cut development stage and stronger heterogeneity, it is found that under the control of stable interbedded barriers, the oil saturation differences of remaining oil between layers are relatively large. Under the influence of the oil saturation differences, the fluid flow in the reservoir will also change, further aggravating the interference of the interlayer permeability ratio on water flooding production. Therefore, the present invention combines the reservoir index of oil saturation and the static index of permeability ratio to comprehensively design an injection-production plan for interlayer optimization combination, improving the recovery factor of water flooding production.

[0041] Specifically, taking a certain target area as an example, the embodiments of the injection-production method for interlayer optimization combination of the present invention will be described below. The injection-production method is as Figure 1 shown and includes the following steps:

[0042] 1) Establish a basic three-dimensional geological model.

[0043] The basic three-dimensional geological model is established based on the geological parameters of the reservoir. The geological parameters include the depth, type, thickness, rhythm, and facies belt of each formation.

[0044] The geological parameters in the basic three-dimensional geological model include the depth, type, thickness, rhythm, and facies belt of each formation. Among them, the depth, thickness, type, and rhythm refer to the actual reservoir parameters, and facies-controlled modeling (facies-controlled modeling is to establish a reservoir property model with various facies as constraints; facies, such as sedimentary microfacies, lithofacies, seismic facies, logging facies, and other parameters) is adopted. As Figure 3a 、 Figure 3b shown, the grid step size of the three-dimensional geological model is designed to be 5m×5m×0.25m, and the total number of grids is 180×150×20 = 540000.

[0045] In order to save simulation costs, the basic three-dimensional geological model is a standard abstract model of the target reservoir established based on the geological parameters of the target reservoir, and is not the same size as the actual target reservoir. This model extracts the characteristics of the actual target reservoir for establishment. For example: the sedimentary facies belt, reservoir burial depth, and rhythm type of the actual target reservoir. The model parameters and the actual reservoir parameters are shown in Table 1:

[0046] Table 1 Setting of model parameters and actual reservoir parameters

[0047] Parameter Actual reservoir value Model parameter Reservoir burial depth (m) 2340-2440 2400-2410 Sedimentary facies belt Channel, channel flank, sheet sand Channel, channel flank, sheet sand Rhythm type Positive rhythm, compound positive rhythm Positive rhythm

[0048] Note: In Table 1, positive rhythm means that the permeability increases from top to bottom.

[0049] Of course, as other embodiments, it is also possible to establish a three-dimensional geological model that is exactly the same as the target reservoir size, number of wells, and other parameters, but the cost is relatively high. The focus of the present invention is to determine the actual injection and production schemes for each region of the target reservoir by using the simulated results after simulation. Therefore, a standard abstracted model can be adopted.

[0050] 2) Obtain the oil saturation data of the target reservoir. The oil saturation data includes the oil saturation of each formation in each single well of the target reservoir, and establish an oil saturation database of the target reservoir.

[0051] For the target reservoir, according to the single-well logging data of the reservoir in different development stages and the coring of each formation of all wells, the oil saturation monitoring data of the reservoir is obtained through calculation to study the interlayer optimization combination mode that meets different development stages, and then an oil saturation database of the target reservoir is established.

[0052] The oil saturations of different formations of Well 2-83 in the target reservoir are shown in Table 2. When establishing the oil saturation data of the target reservoir, the oil saturation data of several wells are collected, such as Figure 2 Well 3-C128, Well 3-345, Well 3-31, Well 2-C71, Well 2-83, Well 2-39, Well 3-177, Well 2-561 in

[0053] Table 2 Oil Saturation Monitoring Table of Well 2-83

[0054]

[0055]

[0056] 3) According to the oil saturation data obtained in step 2), draw an oil saturation scatter plot, conduct cluster analysis on the saturation data, and divide the target reservoir into three oil saturation combination regions according to the cluster analysis results; each oil saturation combination region corresponds to an oil saturation interval; determine the designed oil saturation values corresponding to each formation in the simulated three-dimensional geological model according to the oil saturation interval.

[0057] Use the oil saturation data to draw as Figure 2The shown scatter plot of oil saturation divides the target oil reservoir into three oil saturation combination regions after summarizing and processing the data using the principle of cluster analysis. The oil saturation interval of the first oil saturation combination region is [50%, 65%]; the oil saturation interval of the second oil saturation combination region is [20%, 35%]; the oil saturation interval of the third oil saturation combination region is [20%, 55%]. It can be seen that the first oil saturation combination region is a region with a relatively high oil saturation combination interval, a high-high oil saturation combination region, the second oil saturation combination region is a region with a relatively low oil saturation combination interval, a low-low oil saturation combination region, and the third oil saturation combination region is a region with a relatively large span of oil saturation combination interval, a high-low oil saturation combination region.

[0058] The clustering analysis algorithm in this step can adopt clustering algorithms in existing technologies such as the K-Means algorithm or the DBSCAN algorithm.

[0059] The designed oil saturation values corresponding to each formation in the simulated three-dimensional geological model are established based on the oil saturation interval and can be determined by interpolation. For example: if the oil saturation interval is [50%, 65%], and there are three formations in the simulated three-dimensional geological model, then the designed oil saturation values corresponding to each formation are 50%, 57.5%, and 65%. The corresponding order of the designed oil saturation values and the formations can be changed or randomly set as long as the oil saturation interval is satisfied.

[0060] 4) Obtain the permeability data of the target oil reservoir. The permeability data includes the permeability of each formation in each single well of the target oil reservoir, and design the number of levels of permeability grade difference according to the permeability data.

[0061] Based on the single well logging interpretation results of the oil reservoir, a permeability database is established. Part of the logging interpretation results of a single well are shown in Table 3:

[0062] Table 3 Partial logging interpretation results of each single well

[0063]

[0064]

[0065] Based on the above permeability database, find the maximum and minimum permeabilities. Divide the maximum permeability by the minimum permeability and round the resulting ratio to obtain the designed number of levels (since there is a large amount of data in the entire permeability database, in order to better meet the requirements, the maximum and minimum permeabilities can be selected from the database of the target formation as needed for the design of permeability grade difference). The designed number of levels of permeability grade difference is 8. Combining with the interval data of saturation, the permeability grade difference design for each saturation interval is obtained, as shown in Table 4:

[0066] Table 4 Permeability Grade Difference Design Scheme

[0067]

[0068]

[0069] 5) Find all the actual permeability values corresponding to each depth in the set formation of the basic three-dimensional geological model from the permeability data. Take the average of all the actual permeability values corresponding to each depth to obtain the permeability values of each depth in the set formation of the basic three-dimensional geological model. Then take the average of the permeability values of each depth in the set formation to obtain the designed permeability value of the set formation. According to the determined number of levels of permeability grade difference and the designed permeability value of the set formation, determine the designed permeability values corresponding to each formation in the simulated three-dimensional geological model.

[0070] Find all the actual permeability values corresponding to each depth in the set formation of the basic three-dimensional geological model from the permeability data. According to the value-taking principle of model parameters and the grid division results, take the average of the permeability values of each depth from top to bottom longitudinally in the three-dimensional geological model (considering plane heterogeneity and longitudinal rhythm, the average of the permeability values of each depth is the average of the permeabilities of the same sedimentary facies), as shown in Table 5:

[0071] Table 5 Value-taking of Model Parameters and Grid Division (Taking the Channel Facies as an Example)

[0072]

[0073] In Table 5, the average of all the actual permeability values corresponding to each depth in the first formation is 50, 60, 0, 70, 80, 90, 100, and thus the designed permeability value of the channel facies corresponding to the first formation is 75. Similarly, the designed permeability value of the channel facies for the third formation is 75. At this time, the permeability grade difference between the first formation and the third formation is 1. Then change the permeability grade difference in the three-dimensional geological model to obtain different settings of permeability grade difference. On the basis of the model with a permeability grade difference of 1, by changing the permeability multiple of the third formation, the designed permeability grade difference value between the first formation and the third formation is achieved, as shown in Table 6 below.

[0074] Table VI Average Permeability Ratio Design Table for Low-Low Saturation Model (Taking Channel Facies as an Example)

[0075]

[0076] Table VI is the permeability design table corresponding to the second oil saturation combination area. Similarly, for the first oil saturation combination area and the third oil saturation combination area, the same method is used to design different permeability ratios.

[0077] 6) Input the designed oil saturation values corresponding to each formation obtained in step 3) and the designed permeability values corresponding to each formation obtained in step 5) into the basic three-dimensional geological model to obtain the simulated three-dimensional geological models for each oil saturation interval and each permeability ratio.

[0078] Table V above describes the numerical values of each parameter of the simulated three-dimensional geological model taking the low-low oil saturation combination as an example. According to the relationship between lithofacies, physical properties and the change of oil saturation, the better the physical properties, the higher the oil saturation, and the higher the lithology coefficient, the higher the oil saturation. In the three-dimensional model established this time, the average saturation value of the first formation of the formation is set to 0.2, and the average saturation value of the third formation of the formation is set to 0.35. Among them, the specific data corresponding to each grid number (i.e., each depth) in each formation are shown in Table V, following the principle of being within the actual fluid saturation value range of the reservoir and conforming to the lithology change. In each grid number of the set formation, that is, the oil saturation data corresponding to each set depth should be as close as possible to the average saturation value of the formation. In the three-dimensional model, the oil saturation of the formation with a lower oil saturation (i.e., the set formation with an average oil saturation of 0.2) at each depth should not exceed the average saturation value (i.e., 0.35) of the set formation with a higher average oil saturation (i.e., the set formation with an average oil saturation of 0.35). According to this method, the simulated three-dimensional geological model under the low-low oil saturation combination is finally established.

[0079] Similarly, according to the designed oil saturation values corresponding to each formation in each oil saturation interval obtained in step 3), the simulated three-dimensional geological models for each oil saturation interval and each permeability ratio are obtained.

[0080] 7) Simulate the recovery factor corresponding to each oil saturation interval and each permeability ratio in the simulated three-dimensional geological model.

[0081] According to the actual fluid parameters of the reservoir, set the reservoir fluid parameters of the simulated three-dimensional geological model, and according to the reservoir development well pattern, set one injection and two production, with three injection-production well groups. The injection wells W1-W3 and the production wells P1-1, P3-1a, P2-1a are located in the channel facies zone, while P3-2a, P1-2, P2-2a are located in the thin sand facies zone at the side edge. The well spacings are 245 meters, 125 meters, and 290 meters respectively (the distribution map is in Figure 3a and Figure 3b Based on the model which is an abstraction of the target reservoir, the coordinates of the wells in the model are not the same as those of the wells in the actual reservoir. Figure 3a and Figure 3b The setting of the wells in Figure 4a and Figure 4b refers to the positions of the wells in the actual reservoir. For example, if there are several wells distributed in the channel and the channel flank of the target reservoir, then several representative wells can be set in the channel and the channel flank of the model. The wells in the model are virtualized wells, and the well spacing is the same as that of the wells in the target reservoir), and the final simulated model is obtained. The final models of the high-low oil saturation combination area under different permeability contrasts are shown in Figure 4c 、 Figure 4d and so on. Furthermore, through simulation, the cumulative oil production comparison curves shown in Figure 5a 、 Figure 5b and so on, and the oil displacement effect diagrams shown in Figure 5c 、 Figure 6a 、 Figure 6b 、 Figure 6c 、 Figure 6d are obtained ( Figure 6a 、 Figure 6b 、 Figure 6c 、 Figure 6d represent the oil displacement effects of each formation when the high-low oil saturation combination has permeability contrasts of 3, 5, 6, and 7. The upper part corresponds to the oil displacement effect of the first formation in Table 5, and the lower part corresponds to the oil displacement effect of the third formation in Table 5).

[0082] The actual reservoir parameters and the reservoir fluid parameters in the model are shown in Table 7:

[0083] Table 7 Reservoir Fluid Parameter Table

[0084]

[0085] Numerical simulation is carried out on the models established above with different saturation intervals and different permeability contrasts, and the recovery factors of the low-low oil saturation combination area, Figure 7a the high-low (i.e., low-high) oil saturation combination area, Figure 7b and the high-high oil saturation combination area under different permeability contrasts are obtained. Figure 7c

[0086] 8) At the oil recovery rate obtained in step 7), find the mutant permeability ratio with an oil recovery rate decline exceeding the set threshold. Take the permeability ratio of the level above the mutant permeability ratio as the critical permeability ratio for combined injection / separate injection. When the permeability ratio exceeds the critical permeability ratio, use the separate injection method; when it does not exceed the critical permeability ratio, use the combined injection method.

[0087] For the second oil saturation combination area, that is, the low-low oil saturation combination area, it can be seen from the numerical simulation results that as the permeability ratio increases, the oil recovery rate shows a downward trend. After the permeability ratio is greater than 7 times, the decline rate of the oil recovery rate is relatively fast, and the decline of the oil recovery rate exceeds the set threshold (the set threshold here is set according to experience). The number of levels of the mutant permeability ratio is 8, and the critical permeability ratio is obtained as 7 times. Therefore, it is determined that the reasonable permeability ratio should be controlled within 7 times. It is concluded that for the second oil saturation combination area, when the permeability ratio is within 7 times, the combined injection method is used for water injection development; when the permeability ratio exceeds 7 times, the separate injection method is used for water injection development, ensuring that the permeability ratio of each separate injection interval is controlled within 7 times to improve the water injection utilization rate of each layer.

[0088] For the third oil saturation combination area, that is, the high-low oil saturation combination area, it can be seen from the numerical simulation results that the reasonable permeability ratio should be controlled within 5 times to achieve a relatively high oil recovery rate. After the permeability ratio is greater than 5 times, the interlayer utilization is unbalanced and the oil recovery rate drops rapidly. The number of levels of the mutant permeability ratio is 6, and the critical permeability ratio is obtained as 5 times. Considering comprehensively, the reasonable permeability ratio should be controlled within 5 times. It is concluded that for the third oil saturation combination area, when the permeability ratio is within 5 times, the combined injection method is used for water injection development; when the permeability ratio exceeds 5 times, the separate injection method is used for water injection development.

[0089] For the first oil saturation combination area, that is, the high-high oil saturation combination area, it can be seen from the numerical simulation results that as the permeability ratio increases, the oil recovery rate decreases. The number of levels of the mutant permeability ratio is 7, and the critical permeability ratio is obtained as 6 times. The reasonable permeability ratio should be controlled within 6 times to achieve a relatively high oil recovery rate; compared with the second oil saturation combination area, the limit of the permeability ratio can be appropriately increased, but it is still lower than the reasonable permeability ratio limit of the third oil saturation combination area. It is concluded that for the first oil saturation combination area, when the permeability ratio is within 6 times, the combined injection method is used for water injection development; when the permeability ratio exceeds 6 times, the separate injection method is used for water injection development.

[0090] It can be seen that the higher the oil saturation, the higher the oil recovery rate; under different oil saturation combinations, the greater the permeability ratio, the lower the oil recovery rate, and the turning points of the rapid decline are different; the greater the difference in oil saturation between layers, the smaller the permeability ratio required for effective utilization.

[0091] 9) Determine the injection-production method of the current oil reservoir according to the oil saturation interval and permeability ratio of the current area, and combine the subdivision combination conclusion obtained in step 6) to complete the injection-production.

[0092] Combined with the reasonable permeability ratio optimization limit under the above different saturation combinations, considering the actual development situation of the target area, comprehensively determine the optimized combined injection-production plan. A total of 11 well-times of adjusted subdivision injection-production work have been implemented. After implementation, the water absorption thickness has increased by 7.8 percentage points, the comprehensive decline has slowed down by 5.06 percentage points compared with the same period, and the water drive utilization degree has increased by 4.7 percentage points.

[0093] Specifically, the recommended injection-production plan for controlling the interlayer ratio in the target area is shown in Table 8:

[0094] Table 8 Recommended reasonable injection-production plans under different saturation combinations

[0095]

[0096] It can be seen from Table 8 that for the low-low oil saturation combination area, when the permeability ratio is within 7 times, the combined injection method is used for water injection development; when the permeability ratio exceeds 7 times, the separate injection method is used for water injection development; for the high-low oil saturation combination area, when the permeability ratio is within 5 times, the combined injection method is used for water injection development; when the permeability ratio exceeds 5 times, the separate injection method is used for water injection development. Furthermore, the optimization of the vertical permeability ratio limit in the target area is completed, the optimal vertical permeability ratio limit under different oil saturations is determined, and it guides the interlayer optimization combination of the oil reservoir development wells, providing an optimization combination basis for further improving the vertical utilization degree of the oil reservoir during the high water cut development period.

[0097] In the above embodiment, the target oil reservoir is divided into three oil saturation combination areas according to the clustering analysis results of the oil saturation; the oil saturation interval of the first oil saturation combination area is [x1, x2], x1 < x2; the oil saturation interval of the second oil saturation combination area is [x3, x4], x3 < x4; the oil saturation interval of the third oil saturation combination area is [x5, x6], x5 < x6; x4 < x1; x3 ≤ x5 < x4; x1 < x6 < x2. As other implementation manners, it is only necessary to divide the target oil reservoir into at least two oil saturation combination areas, and the number of divisions of the oil saturation interval and the specific oil saturation data corresponding to the saturation interval are not limited in this invention.

[0098] The present invention combines the oil saturation and the permeability ratio to determine the injection-production method of the interlayer optimization combination, guides the oil reservoir development, improves the recovery rate, and further improves the water drive utilization degree and water drive swept volume of each layer in the high water cut oil reservoir.

Claims

1. An injection-production method with optimized interlayer combination, characterized in that: The following steps are involved: 1) Construct a basic 3D geological model based on the geological parameters of the target reservoir, including the depth, type, thickness, rhythmicity, and facies of each stratum; 2) Obtaining oil saturation data of the target oil reservoir; the oil saturation data is the oil saturation of each formation in each single well of the target oil reservoir; Cluster analysis is performed on the oil saturation data. Based on the cluster analysis results, the target reservoir is divided into at least two oil saturation combination areas. Each oil saturation combination area corresponds to an oil saturation interval. Based on the oil saturation interval, the oil saturation design value corresponding to each formation in the simulated three-dimensional geological model is determined. 3) obtaining permeability data of the target reservoir; the permeability data including the permeability of each formation in each single well of the target reservoir; determining the number of permeability differentials of the target reservoir based on the permeability data; obtaining a permeability design value of a predetermined formation in the basic three-dimensional geological model based on a correspondence between the permeability data and the formations in the basic three-dimensional geological model; and determining the corresponding permeability design values of each formation in the simulated three-dimensional geological model based on the determined number of permeability differentials and the permeability design value of the predetermined formation; 4) inputting the oil saturation design value corresponding to each stratum obtained in step 2) and the permeability design value corresponding to each stratum obtained in step 3) into the basic three-dimensional geological model to obtain a simulated three-dimensional geological model for each oil saturation interval and each permeability differential; 5) Simulate the recovery rate corresponding to each permeability differential in each oil saturation interval in the simulated 3D geological model, find the sudden permeability differential at which the recovery rate drop exceeds the set threshold, and use the permeability differential of the previous level of the sudden permeability differential as the critical permeability differential for combined injection / separate injection. If the permeability differential exceeds the critical permeability differential, separate injection is used; if the permeability differential does not exceed the critical permeability differential, combined injection is used. 6) Determine the injection and production method for the current area based on the oil saturation range and permeability difference in the current area, and then complete the injection and production.

2. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: In the step 2), the target oil reservoir is divided into three oil saturation combination areas; the oil saturation interval of the first oil saturation combination area is [x1, x2], x1<x2; the oil saturation interval of the second oil saturation combination area is [x3, x4], x3<x4; the oil saturation interval of the third oil saturation combination area is [x5, x6], x5<x6; x4<x1; x3≤x5<x4; x1<x6<x2.

3. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: In step 3), the process of obtaining the permeability design value of a set stratum in the basic three-dimensional geological model is as follows: finding all actual permeability values corresponding to various depths in the set stratum of the basic three-dimensional geological model in the permeability data, averaging all actual permeability values corresponding to various depths to obtain the permeability values of various depths of the set stratum of the basic three-dimensional geological model, and then averaging the permeability values of various depths of the set stratum to obtain the permeability design value of the set stratum.

4. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: The oil saturation data is obtained through core and well logging interpretation and calculation.

5. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: The permeability data is obtained based on well logging data.

6. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: The cluster analysis algorithm uses the K-Means algorithm.

7. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: The grid step size in the basic three-dimensional geological model is 5m×5m×0.25m, and the total number of grids is 180×150×20.

8. The injection-production method of interlayer optimization combination according to claim 1, characterized in that: The permeability difference level of the target reservoir is determined according to the maximum permeability and the minimum permeability in the permeability data.

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