Method for finely evaluating effective injection-production connectivity coincidence rate of low-permeability reservoir

Abstract

The invention relates to the field of oil-gas exploration and development of low-permeability reservoirs, in particular to a method for finely evaluating the effective injection-production connectivity coincidence rate of a low-permeability reservoir, which comprises the following steps of: constructing a minimum injection-production unit of an injection-production well group in a water injection development research area; judging the static connectivity of the sand body of the injection-production well group; the dynamic connectivity of the injection and production well group sand bodies is judged; and effective injection-production connectivity coincidence rate analysis: statistics is performed according to connectivity sand bodies of the oil production wells corresponding to the water injection wells and the effective conditions of the connectivity sand bodies, and the proportion of the effective injection-production connectivity well number in the total well number is obtained as the effective injection-production connectivity coincidence rate. According to the method, fine evaluation of connectivity between injection and production wells on a minimum unit is achieved by constructing a static injection and production calculation unit; static sand body connectivity evaluation and dynamic production effectiveness characteristics are combined, and fine and quantitative evaluation of the effective injection-production connectivity coincidence rate in low-permeability reservoir water injection development is achieved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development in low-permeability reservoirs, and in particular to a method for finely evaluating the effective injection-production connectivity rate of low-permeability reservoirs. Background Technology

[0002] Low-permeability reservoirs have poor physical properties, resulting in low recovery rates when relying on natural energy. Water injection is typically employed to improve water drive control and replenish formation energy. Vertically, low-permeability reservoirs often feature multiple stacked sand bodies with rapid lateral changes, leading to uneven water injection effectiveness and significant water channeling and flooding problems. The connectivity of sand bodies between injection and production wells not only affects the development well network density and water injection method but also the final oil and gas recovery rate. Therefore, a detailed study of sand body connectivity between injection and production wells using logging data from dense well networks is necessary. Based on this, and combined with production data, the water-breaking and effectiveness characteristics of injection-production well groups can be analyzed to evaluate the dynamic and static connectivity of sand bodies between injection and production wells in low-permeability reservoirs, providing a basis for rational reservoir development.

[0003] Currently, many scholars have conducted extensive research on the evaluation of connectivity of sandstone bodies in low-permeability reservoirs and the effectiveness of water injection. This includes the vertical stacking pattern and lateral contact pattern of sandstone bodies. Connectivity is a relative concept, generally a combination of the characteristics of the reservoir sandstone body and the sandstone bodies encountered in a single well or well group.

[0004] Currently, injection-production well groups are generally used as the basic unit for analyzing and evaluating the effectiveness of water injection. However, due to the rapid vertical and horizontal changes of sand bodies in low-permeability reservoirs, sand body connectivity analysis based on injection-production well groups cannot meet the research accuracy requirements of fine-grained dynamic analysis of water injection. Generally, the effectiveness characteristics of representative oil wells represent the effectiveness of the injection-production well group, which cannot truly reflect the effectiveness characteristics of the injection-production well group. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a method for refining the effective injection-production connectivity rate of low-permeability reservoirs by constructing a more detailed sand body connectivity model based on traditional injection-production well groups, which better aligns with geological understanding and enhances the reliability of dynamic analysis results.

[0006] This invention provides a method for finely evaluating the effective injection-production connectivity rate of low-permeability reservoirs, comprising the following steps: Step 1: Construct the smallest injection-production unit for injection-production well groups within the water injection development research area: the static injection-production calculation unit; Step 2: Determine the static connectivity of the sand bodies in the injection-production well group; Step 3: Determine the dynamic connectivity of the sand bodies in the injection-production well group; Step 4: Effective Injection-Production Connectivity Compliance Rate Analysis. Based on Steps 2 and 3, the connectivity sand bodies and effectiveness of the oil production wells corresponding to the water injection wells in the injection-production well group are statistically analyzed. The proportion of the number of wells with effective injection-production connectivity in the total number of wells is the effective injection-production connectivity compliance rate.

[0007] Preferably, the method for constructing the static injection-collection calculation unit in step one is as follows: (1) Within the water injection development research area, the wells are divided into injection-production well groups, with the injection wells as the center. (2) Based on the injection-production well group unit, the water injection wells are connected to the surrounding oil production wells one by one to construct a static injection-production calculation unit.

[0008] Preferably, the specific method for determining the static connectivity of the sand bodies in the injection-production well group in step two is as follows: (1) Based on the traditional criteria and methods for oil layer correlation, and in accordance with the principle of “cyclic correlation and hierarchical control”, the strata are divided into oil layer group, sub-oil layer group, and sub-layer, and then further subdivided into single sand bodies; (2) The sand body stacking type is divided based on the oil and gas concentration area within a single sand body as the target layer; (3) Based on the stacking type of single sand bodies in (2) and the principle that sand bodies in the same deposition period between injection and production wells have similar logging curve morphology, draw a sand body connectivity diagram between injection wells and production wells for single sand bodies under the control of small layer level. (4) Analysis of the connectivity of individual sand bodies, and quantitative evaluation of the static connectivity of individual sand bodies in each static injection-production unit: Based on the single sand body division, the average effective sand body connectivity thickness and average sand body connectivity coefficient between the injection well and other oil production wells in each static injection-production unit are statistically analyzed and used as the inter-well connectivity thickness of that static injection-production calculation unit. H L Inter-well connectivity coefficient λ; Inter-well connectivity thickness H L : In the formula: The thickness of the inter-well connectivity is in meters (m). Let the effective thickness (m) of the i-th interconnected single sand body between wells be denoted as ; Inter-well connectivity coefficient λ: In the formula: The inter-well connectivity coefficient; The total thickness of the sand body in a single well is in meters (m). By statistically analyzing the thickness and connectivity coefficient of the connected sand body in each static injection-production unit at the single sand body level, the connectivity characteristics between water injection wells and oil production wells in the plane are quantitatively evaluated; the larger the connectivity thickness and connectivity coefficient values, the better the static connectivity between injection and production wells.

[0009] Preferably, the specific method for determining the dynamic connectivity of the sand bodies in the injection-production well group in step three is as follows: (1) Analyze the effectiveness characteristics of oil production wells. The injection and production dynamic data of each well group are in monthly time series. The production volume, oil production, water cut of each oil production well and the water injection volume of the injection well are statistically analyzed. The connectivity of single sand bodies is analyzed from the changes of the three parameters of production volume, oil production, and water cut of the oil production wells. The effectiveness characteristics are as follows: ①Significant effect: Changes in oil well parameters, with a significant increase in fluid production and oil production, and a decrease or no change in water cut, reflect high dynamic sand body connectivity between the injection well and the production well; ② Generally effective: Changes in oil well parameters, with fluid volume increasing by less than 30%, oil volume increasing by less than 30%, and water cut remaining unchanged or decreasing only slightly, indicate a high degree of dynamic sand body connectivity between the injection well and the production well; ③ Obvious water production: Changes in oil well parameters, such as a significant increase in fluid production, no change or decrease in oil production, and a significant increase in water cut, indicate high dynamic sand body connectivity between the injection well and the production well. ④ Ineffective: Changes in well parameters, such as decreased fluid production, decreased oil production, increased or unchanged water cut, indicate low dynamic sand body connectivity between the injection well and the production well. (2) Statistically analyze the connectivity thickness and connectivity coefficient under different effective characteristics, and analyze the correlation between sand body stacking relationship and effective characteristics, connectivity thickness and connectivity coefficient.

[0010] Preferably, the effective injection-sampling connectivity compliance rate analysis in step four is as follows: Based on the research results of sand body connectivity between water injection wells and oil production wells within the static injection-production calculation unit in step two, and combined with the results of step three, the connectivity sand bodies of the corresponding oil production wells of water injection wells and their effectiveness are statistically analyzed, and the calculation formula for the effective injection-production connectivity compliance rate is obtained as follows: Effective injection-production connectivity compliance rate = (Number of wells with significant effect + Number of wells with general effect) / Total number of wells; Among them, those that show obvious effects and those that show moderate effects are considered effective injection-progression connections, while those that show no effect are considered ineffective injection-progression connections.

[0011] This invention achieves a refined evaluation of the connectivity between injection and production wells at the smallest unit level by constructing a "static injection-production calculation unit." Through detailed characterization at the single sand body level and the introduction of quantitative parameters such as connectivity thickness and connectivity coefficient, it significantly improves the objectivity and accuracy of static sand body connectivity judgment. By combining static sand body connectivity evaluation with dynamic production effectiveness characteristics, it achieves a refined and quantitative evaluation of the effective injection-production connectivity compliance rate in low-permeability reservoir water injection development, which is more consistent with geological understanding and provides a scientific basis for water injection control and measure optimization in the mid-to-late stages of oilfield development. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the division of injection and production well groups.

[0013] Figure 2 This is a schematic diagram illustrating the process of statistically analyzing the connectivity thickness of injection and production well groups.

[0014] Figure 3 In the example, the length is 21. 3-（1+2） Schematic diagram of oil reservoir injection and production well group division.

[0015] Figure 4 In the example, the length is 21. 3-（1+2） Schematic diagram of static injection and extraction calculation unit.

[0016] Figure 5 This is a comprehensive columnar section showing the stratigraphic division of the two long layers in the example.

[0017] Figure 6 In the example, the length is 21. 3-（1+2） A comprehensive columnar section for the division of a single sand body.

[0018] Figure 7 In the example, the length is 21. 3-（1+2） Schematic diagram of multi-stage sand body stacking type.

[0019] Figure 8 This is a diagram showing the sand body connectivity of the two injection-production well groups in the embodiment.

[0020] Figure 9 In the example, the length is 21. 3-（1+2） Layer connectivity thickness frequency diagram.

[0021] Figure 10 In the example, the length is 21. 3-（1+2） Frequency diagram of layer connectivity coefficients.

[0022] Figure 11 In the example, the length is 21. 3-（1+2） Layer static injection and extraction unit connectivity thickness distribution diagram.

[0023] Figure 12 In the example, the length is 21. 3-（1+2） Distribution diagram of connectivity coefficients of static injection and extraction units in the layer.

[0024] Figure 13 This is a schematic diagram of the sand body distribution characteristics of the Ding 4430-4 well group in the example.

[0025] Figure 14 This is a schematic diagram of the oil layer and production distribution characteristics of the Ding 4430-4 well group in the example.

[0026] Figure 15 The injection-production curve of well group 4430-4 is shown in the example.

[0027] Figure 16 In the example, the length is 21. 3-（1+2） A diagram showing the relationship between layer effectiveness and connectivity thickness.

[0028] Figure 17 In the example, the length is 21. 3-（1+2） A graph showing the relationship between layer effectiveness and connectivity coefficient.

[0029] Figure 18 In the example, the length is 21. 3-（1+2） Distribution chart of layer-by-layer effectiveness. Detailed Implementation

[0030] This invention provides a method for finely evaluating the effective injection-production connectivity rate of low-permeability reservoirs, comprising the following steps: Step 1: Construct the smallest injection-production unit for injection-production well groups within the water injection development research area: the static injection-production calculation unit; Step 2: Determine the static connectivity of the sand bodies in the injection-production well group; Step 3: Determine the dynamic connectivity of the sand bodies in the injection-production well group; Step 4: Effective Injection-Production Connectivity Compliance Rate Analysis. Based on Steps 2 and 3, the connectivity sand bodies and effectiveness of the oil production wells corresponding to the water injection wells in the injection-production well group are statistically analyzed. The proportion of the number of wells with effective injection-production connectivity in the total number of wells is the effective injection-production connectivity compliance rate.

[0031] The method for constructing the static injection and extraction calculation unit in step one is as follows: (1) Within the water injection development research area, the wells are divided into injection-production well groups, with the injection wells as the center. (2) Based on the injection-production well group unit, the water injection wells are connected to the surrounding oil production wells one by one to construct a static injection-production calculation unit.

[0032] The specific method for determining the static connectivity of sand bodies in the injection-production well group in step two is as follows: (1) Based on the traditional criteria and methods for oil layer correlation, and in accordance with the principle of “cyclic correlation and hierarchical control”, the strata are divided into oil layer group, sub-oil layer group, and sub-layer, and then further subdivided into single sand bodies; (2) The sand body stacking type is divided based on the oil and gas concentration area within a single sand body as the target layer; (3) Based on the stacking type of single sand bodies in (2) and the principle that sand bodies in the same deposition period between injection and production wells have similar logging curve morphology, draw a sand body connectivity diagram between injection wells and production wells for single sand bodies under the control of small layer level. (4) Analysis of the connectivity of individual sand bodies, and quantitative evaluation of the static connectivity of individual sand bodies in each static injection-production unit: Based on the single sand body division, the average effective sand body connectivity thickness and average sand body connectivity coefficient between the injection well and other oil production wells in each static injection-production unit are statistically analyzed and used as the inter-well connectivity thickness of that static injection-production calculation unit. H L Inter-well connectivity coefficient λ; Inter-well connectivity thickness H L : In the formula: The thickness of the inter-well connectivity is in meters (m). Let the effective thickness (m) of the i-th interconnected single sand body between wells be denoted as ; Inter-well connectivity coefficient λ: In the formula: The inter-well connectivity coefficient; The total thickness of the sand body in a single well is in meters (m). By statistically analyzing the thickness and connectivity coefficient of the connected sand body in each static injection-production unit at the single sand body level, the connectivity characteristics between water injection wells and oil production wells in the plane are quantitatively evaluated; the larger the connectivity thickness and connectivity coefficient values, the better the static connectivity between injection and production wells.

[0033] The specific method for determining the dynamic connectivity of sand bodies in the injection-production well group in step three is as follows: (1) Analyze the effectiveness characteristics of oil production wells. The injection and production dynamic data of each well group are in monthly time series. The production volume, oil production, water cut of each oil production well and the water injection volume of the injection well are statistically analyzed. The connectivity of single sand bodies is analyzed from the changes of the three parameters of production volume, oil production, and water cut of the oil production wells. The effectiveness characteristics are as follows: ①Significant effect: Changes in oil well parameters, with a significant increase in fluid production and oil production, and a decrease or no change in water cut, reflect high dynamic sand body connectivity between the injection well and the production well; ② Generally effective: Changes in oil well parameters, with fluid volume increasing by less than 30%, oil volume increasing by less than 30%, and water cut remaining unchanged or decreasing only slightly, indicate a high degree of dynamic sand body connectivity between the injection well and the production well; ③ Obvious water production: Changes in oil well parameters, such as a significant increase in fluid production, no change or decrease in oil production, and a significant increase in water cut, indicate high dynamic sand body connectivity between the injection well and the production well. ④ Ineffective: Changes in well parameters, such as decreased fluid production, decreased oil production, increased or unchanged water cut, indicate low dynamic sand body connectivity between the injection well and the production well. (2) Statistically analyze the connectivity thickness and connectivity coefficient under different effective characteristics, and analyze the correlation between sand body stacking relationship and effective characteristics, connectivity thickness and connectivity coefficient.

[0034] Step four involves an analysis of the effective injection-sampling connectivity compliance rate, as detailed below: Based on the research results of sand body connectivity between water injection wells and oil production wells within the static injection-production calculation unit in step two, and combined with the results of step three, the connectivity sand bodies of the corresponding oil production wells of water injection wells and their effectiveness are statistically analyzed, and the calculation formula for the effective injection-production connectivity compliance rate is obtained as follows: Effective injection-production connectivity compliance rate = (Number of wells with significant effect + Number of wells with general effect) / Total number of wells; Among them, those that show obvious effects and those that show moderate effects are considered effective injection-progression connections, while those that show no effect are considered ineffective injection-progression connections.

[0035] The following example is used to illustrate the concept of a length of 21. 3-（1+2） The oil layer illustrates the present invention. Step 1: Constructing a static injection-production calculation unit 1) The water injection development research area is divided into injection-production well group units, centered on the water injection wells, with a length of 21 meters. 3-1 The layer is divided into 15 injection-production well groups, such as Figure 3 As shown.

[0036] 2) Based on the injection-production well group unit, the injection wells were connected to the surrounding production wells to construct a static injection-production calculation unit, 21 meters long. 3-（1+2） The layer is divided into 80 static injection and acquisition calculation units, such as Figure 4 As shown; Step 2: Based on the traditional criteria and methods for oil layer correlation and division, and following the principle of "cyclic correlation and hierarchical control", the strata are divided into oil layer groups, sub-oil layer groups, and sub-layers, and further subdivided into single sand bodies. (1) Division of the Chang 2 oil layer group: Based on the standard well and well-connected profile method, according to the principle of “marker layer control, cycle comparison, grade control, and similar thickness ratio”, the Chang 2 oil layer group is divided into three sub-oil layer groups: Chang 21, Chang 22 and Chang 23. The Chang 2 oil-bearing formation is primarily delineated based on three marker beds: K9, K8, and K7. These marker beds are characterized by their distinct features, wide and stable distribution, and have been encountered in all wells within the area. The K9 marker bed, used to delineate the Chang 1 and Chang 2 oil-bearing formations, is located at the bottom of the Chang 1 formation and consists of approximately 2 meters of black mudstone, shale, and tuffaceous mudstone interbedded with tuffaceous mudstone. Its electrical characteristics include high gamma ray values, high sonic transit time, and low resistivity. The K7 marker bed, used to delineate the Chang 2 and Chang 3 oil-bearing formations, is located at the bottom of the Chang 2 formation and consists of approximately 1 meter of grayish-black mudstone, carbonaceous mudstone, and tuffaceous mudstone. Its electrical characteristics include high natural gamma ray values, high sonic transit time, and high resistivity. The K8 marker bed is used to delineate the Chang 21 and Chang 22 sub-oil layers. Located at the top of the Chang 22 sub-oil layer group, it consists of black mudstone with a thickness of 1-3 m, exhibiting electrical characteristics such as low resistivity, high acoustic transit time, and high natural gamma value. Figure 5 As shown in Table 2; Table 2. Scheme for dividing single sand bodies in the Chang 2 oil layer group of the oilfield. Division of the Chang 21 sub-oil layer group: Relatively stable argillaceous interlayers develop between the smaller layers within the Chang 21 sub-oil layer group, further subdividing the Chang 21 sub-oil layer group into Chang 21... 1 Length 21 2 Length 21 3 Three smaller layers; such as Figure 5 As shown; With a length of 21 3 Taking the small layer as an example, the length is 21 3 The sublayers are divided into single sand bodies: based on research needs and logging curve characteristics, the length 21 is divided into single sand bodies. 3 The sublayer is divided into 4 sets of single sand bodies, each 21 meters long. 3-1 Length 21 3-2 Length 21 3-3 and 21 3-4 ;like Figure 6 As shown; (2) The sand body stacking type is divided based on the oil and gas concentration area within a single sand body as the target layer; The target layer is the oil and gas concentration zone within a single sandstone body; 21 3 The small layer mainly develops two sedimentary cycles and four sets of single sand bodies; namely, the 21-meter long sand body... 3-1 (I) Length 21 3-2 (II) Length 21 3-3 (III) and length 21 3-4 (IV); The two sets of single sand bodies below are 21 meters long. 3-3 (III) and length 21 3-4 (IV) is mainly a water layer, which will not be analyzed here; the oil and gas concentration area is in the two single sand bodies above, namely, the long 21 3-1 (I) and length 213-2 (II); that is, the target layer is 21 cm long. 3-（1+2） ; Target layer length 21 3（1+2） Sand body stacking type; Target layer length 21 3-（1+2） There are three types of interlayers in the development: clay interlayers, calcareous interlayers, and physical property interlayers; 21 3-（1+2） Includes two single sand bodies, including one 21-meter-long sand body. 3-1 (I) and length 21 3-2 (II); mainly composed of four types of sand body stacking, including isolated type I, isolated type II, vertically separated type I / II, and vertically tangential type I & II; among them, isolated type I consists of 21... 3-1 Composed of a single sand body, the isolated Type II consists of a 21-meter-long sand body. 3-2 Composed of a single sand body, vertically separated Type I / II, with a length of 21... 3-1 He Chang 21 3-2 Composed of two sets of single sand bodies, which appear isolated and unconnected in cross-section; the vertically overlapping type I & II consists of a length of 21... 3-1 He Chang 21 3-2 Composed of two sets of single sand bodies, which appear in overlapping contact in the cross-section, this formation is due to the frequent lateral migration of the river channel and its constant cutting of the underlying channel sand bodies. Figure 7 As shown; (3) Draw a sand body connectivity diagram between the water injection well and the oil production well; Effective water injection requires that the sand bodies between the injection well and the production well be connected. Therefore, it is first necessary to draw a sand body connectivity diagram to more intuitively analyze the sand body connectivity between the injection well and the production well. Figure 8 As shown; (4) Analysis of the connectivity of individual sand bodies. Two indicators, connectivity thickness and connectivity coefficient, were introduced to quantitatively evaluate the static connectivity of the sand bodies in the oil reservoir group in the study area.

[0037] 21 3-（1+2） The layer contains 15 injection-production well groups, which are further divided into 80 static injection-production calculation units. Statistically, the length is 21... 3-1 The layer connectivity thickness is mainly between 4 and 6 meters, followed by 2 to 4 meters; the connectivity coefficient is mainly between 60 and 80%, followed by 40 to 60% and 80 to 100%, see [reference needed]. Figure 9 , Figure 10 , Figure 11 , Figure 12 Table 3; Table 3, Length 21 3-（1+2） Statistical table of sand layer thickness and connectivity coefficient Connectivity thickness / m frequency / % Number of units / port Connectivity coefficient / % frequency / % Number of units / port 2~4 40.5 17 20~40 7.1 3 4~6 47.6 20 40~60 26.2 11 6~8 9.5 4 60~80 42.9 18 8~10 2.4 1 80~100 23.8 10 The connectivity thickness and connectivity coefficient under different effective characteristics were statistically analyzed, and the correlation between sand body stacking relationship and effective characteristics, connectivity thickness and connectivity coefficient were analyzed.

[0038] Step 3: Determine the dynamic connectivity of sand bodies in the injection-production well group. (1) Analyze the characteristics of water injection effectiveness of each well group, taking the Ding 4430-4 well group as an example.

[0039] There are 8 corresponding oil wells, of which 3 are currently shut down. The main reason for the shutdown is the mismatch between injection and production, resulting in insufficient energy replenishment and cessation of pumping. The remaining 5 wells with a better matching relationship show either significant or slight effects. Well Ding 4430-5 began to show positive characteristics after 12 months of water injection, with a significant increase in both fluid and oil production. Well Ding 4430-3 also began to show positive characteristics after 12 months of water injection, with a significant increase in both fluid and oil production, which subsequently stabilized. Figure 13 , Figure 14 , Figure 15 Table 4; Table 4. Statistics on the effectiveness of the Ding 4430-4 injection-production well group (2) The relationship between the stacking relationship of sand bodies and the effective characteristics, as well as the correlation between the thickness of the connection and the connection coefficient.

[0040] Statistical length 21 3-（1+2） The layer comprises 80 static injection-production calculation units. The average connectivity thickness of significantly effective units is 4.98m, the average connectivity thickness of moderately effective units is 4.80m, and the average connectivity thickness of ineffective units is 3.79m. The average connectivity coefficient of significantly effective units is 82%, the average connectivity coefficient of moderately effective units is 84%, and the average connectivity coefficient of ineffective units is 57%. Figure 16 , Figure 17 Table 5. Analysis shows that the greater the connectivity thickness and connectivity coefficient, the better the oil well performance. The connectivity thickness and connectivity coefficient of significantly effective well groups and those with average performance are not significantly different, and are more related to the location of the well group. Figure 16 As shown; Step 4: Effective Injection-Protection Connectivity Compliance Rate Analysis The static and dynamic connectivity of each individual sand body has been quantitatively evaluated. The following section studies the connectivity compliance rate of each major individual sand body. Based on the research results of sand body connectivity between water injection wells and oil production wells within the static injection-production calculation unit in step two, and combined with the results of step three, the connectivity sand bodies and their effectiveness for the corresponding oil production wells of the water injection wells are statistically analyzed. Significantly effective and generally effective connectivity are considered effective injection-production connectivity, while ineffective connectivity is considered ineffective. The formula for calculating the effective injection-production connectivity compliance rate is: Effective Injection-Production Connectivity Compliance Rate = (Number of Significantly Effective Wells + Number of Generally Effective Wells) / Total Number of Wells.

[0041] According to statistics, the length is 21 3-（1+2） The consistency rate of layer injection and collection was 68.9%, as shown in Table 6.

[0042] Table 6 Comparison of the Effectiveness of Key Layers .

Claims

1. A method for finely evaluating the effective injection-production connectivity ratio of low-permeability reservoirs, characterized in that, Includes the following steps: Step 1: Construct the smallest injection-production unit for injection-production well groups within the water injection development research area: the static injection-production calculation unit; Step 2: Determine the static connectivity of the sand bodies in the injection-production well group; Step 3: Determine the dynamic connectivity of the sand bodies in the injection-production well group; Step 4: Effective Injection-Production Connectivity Compliance Rate Analysis. Based on Steps 2 and 3, the connectivity sand bodies and effectiveness of the oil production wells corresponding to the water injection wells in the injection-production well group are statistically analyzed. The proportion of the number of wells with effective injection-production connectivity in the total number of wells is the effective injection-production connectivity compliance rate.

2. The method for finely evaluating the effective injection-production connectivity rate of low-permeability reservoirs as described in claim 1, characterized in that, The method for constructing the static injection and extraction calculation unit in step one is as follows: (1) Within the water injection development research area, the wells are divided into injection-production well groups, with the injection wells as the center. (2) Based on the injection-production well group unit, the water injection wells are connected to the surrounding oil production wells one by one to construct a static injection-production calculation unit.

3. The method for finely evaluating the effective injection-production connectivity ratio of low-permeability reservoirs as described in claim 1, characterized in that, The specific method for determining the static connectivity of sand bodies in the injection-production well group in step two is as follows: (1) Based on the traditional criteria and methods for oil layer correlation, and in accordance with the principle of "cyclic correlation and hierarchical control", the strata are divided into oil layer group, sub-oil layer group, and sub-layer, and then further subdivided into single sand bodies; (2) The sand body stacking type is divided based on the oil and gas concentration area within a single sand body as the target layer; (3) Based on the stacking type of single sand bodies in (2) and the principle that sand bodies in the same deposition period between injection and production wells have similar logging curve morphology, draw a sand body connectivity diagram between injection wells and production wells for single sand bodies under the control of small layer level. (4) Analysis of the connectivity of individual sand bodies, and quantitative evaluation of the static connectivity of individual sand bodies in each static injection-production unit: Based on the single sand body division, the average effective sand body connectivity thickness and average sand body connectivity coefficient between the injection well and other oil production wells in each static injection-production unit are statistically analyzed and used as the inter-well connectivity thickness of that static injection-production calculation unit. H L Inter-well connectivity coefficient λ; Inter-well connectivity thickness H L : In the formula: The thickness of the inter-well connectivity is in meters (m). Let the effective thickness (m) of the i-th interconnected single sand body between wells be denoted as ; Inter-well connectivity coefficient λ: In the formula: The inter-well connectivity coefficient; The total thickness of the sand body in a single well is in meters (m). By statistically analyzing the thickness and connectivity coefficient of the connected sand body in each static injection-production unit at the single sand body level, the connectivity characteristics between water injection wells and oil production wells in the plane are quantitatively evaluated; the larger the connectivity thickness and connectivity coefficient values, the better the static connectivity between injection and production wells.

4. The method for finely evaluating the effective injection-production connectivity rate of low-permeability reservoirs as described in claim 1, characterized in that, The specific method for determining the dynamic connectivity of sand bodies in the injection-production well group in step three is as follows: (1) Analyze the effectiveness characteristics of oil production wells. The injection and production dynamic data of each well group are in monthly time series. The production volume, oil production, water cut of each oil production well and the water injection volume of the injection well are statistically analyzed. The connectivity of single sand bodies is analyzed from the changes of the three parameters of production volume, oil production, and water cut of the oil production wells. The effectiveness characteristics are as follows: ①Significant effect: Changes in oil well parameters, with a significant increase in fluid production and oil production, and a decrease or no change in water cut, reflect high dynamic sand body connectivity between the injection well and the production well; ② Generally effective: Changes in oil well parameters, with fluid volume increasing by less than 30%, oil volume increasing by less than 30%, and water cut remaining unchanged or decreasing only slightly, indicate a high degree of dynamic sand body connectivity between the injection well and the production well; ③ Obvious water production: Changes in oil well parameters, such as a significant increase in fluid production, no change or decrease in oil production, and a significant increase in water cut, indicate high dynamic sand body connectivity between the injection well and the production well. ④ Ineffective: Changes in well parameters, such as decreased fluid production, decreased oil production, increased or unchanged water cut, indicate low dynamic sand body connectivity between the injection well and the production well. (2) Statistically analyze the connectivity thickness and connectivity coefficient under different effective characteristics, and analyze the correlation between sand body stacking relationship and effective characteristics, connectivity thickness and connectivity coefficient.

5. The method for finely evaluating the effective injection-production connectivity ratio of low-permeability reservoirs as described in claim 1, characterized in that, Step four involves an analysis of the effective injection-sampling connectivity compliance rate, as detailed below: Based on the research results of sand body connectivity between water injection wells and oil production wells within the static injection-production calculation unit in step two, and combined with the results of step three, the connectivity sand bodies of the corresponding oil production wells of water injection wells and their effectiveness are statistically analyzed, and the calculation formula for the effective injection-production connectivity compliance rate is obtained as follows: Effective injection-production connectivity compliance rate = (Number of wells with significant effect + Number of wells with general effect) / Total number of wells; Among them, those that show obvious effects and those that show moderate effects are considered effective injection-progression connections, while those that show no effect are considered ineffective injection-progression connections.

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