A method for predicting water injection production capacity of a compact reservoir fracturing horizontal well group
By using a production capacity prediction method with well groups as evaluation units, combined with a zonal material balance and fracture network seepage model, the problem of inter-well interference during water injection and churn in well groups was solved, achieving accurate production capacity prediction and supporting the efficient development of tight oil reservoirs.
Patent Information
- Application Number
- CN202611569335.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-10-12
- Publication Date
- 2026-11-06
AI Technical Summary
Existing methods for predicting the production capacity of fractured horizontal wells in tight oil reservoirs cannot effectively account for inter-well interference during water injection and production capacity prediction under different production conditions, leading to uncertainty in development results.
Using well groups as the overall evaluation unit, the pressure and saturation of each sub-region after water injection are calculated through the regional material balance equation. Combined with the seepage model of the fracture network in tight oil reservoir, the production of each well is calculated. The dynamic interference pressure drop between wells in the well group is calculated through the superposition principle of potential and Newton iteration to correct the production.
It enables accurate prediction of inter-well interference during water injection and churn in well groups, improves the accuracy of production capacity prediction, and provides a theoretical basis for the efficient development of tight oil reservoirs.
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Figure CN123050776A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to a method for predicting the water injection and huff-and-puff production capacity of a horizontal well group in a tight oil reservoir. Background Technology
[0002] With the continuous advancement and in-depth development of global oil and gas exploration and development technologies, the focus of current oil and gas resource development has gradually shifted from conventional reservoirs to unconventional reservoirs that are difficult to exploit, such as low-permeability and tight reservoirs. Among them, tight oil reservoirs have huge reserves and broad development potential, but they are generally buried at great depths, have high temperature and pressure conditions, and poor reservoir properties, resulting in a series of key technical bottlenecks during development, which seriously restrict the large-scale effective exploitation and economic development of this type of reservoir.
[0003] To improve development efficiency, water injection and replenishment based on well groups has been gradually adopted in recent years. This aims to supplement formation energy through coordinated water injection within the well group, further enhancing the cumulative production of fractured horizontal wells and the ultimate recovery rate of the reservoir. However, significant differences in formation properties, production regimes, and development parameters among different wells within a well group lead to considerable uncertainty in development outcomes. Existing production prediction methods mostly use single wells as evaluation units, which cannot effectively characterize the dynamic inter-well interference and uneven energy replenishment issues caused by differences in production regimes among multiple wells under the well group development model. Summary of the Invention
[0004] To address the problem that existing methods for predicting the production capacity of fractured horizontal wells in tight oil reservoirs cannot accurately predict production capacity under different production conditions and calculate inter-well interference during water injection and huff-and-puff processes, this invention proposes a method for predicting the production capacity of water injection and huff-and-puff processes in fractured horizontal well groups in tight oil reservoirs. This method takes the well group as a whole evaluation unit, can effectively consider the impact of inter-well interference on water injection and huff-and-puff production, realize the updating of the physical field during water injection and huff-and-puff processes in each well of the well group, and accurately predict the water injection and huff-and-puff production of the well group. This invention can effectively take into account the pressure interference between wells in a fracturing horizontal well group and the changes in the physical field during water injection and churn of each well, so as to achieve accurate prediction of the production of the horizontal well group and provide theoretical basis and methodological support for the design and optimization of efficient development schemes for tight oil reservoirs.
[0005] The technical solution of the present invention is as follows: A method for predicting the water injection huff and puff production capacity of a fracturing horizontal well group in a tight oil reservoir includes: Step 1: Input the reservoir, production, and well group parameters, and determine the effective control volume boundary of each well based on the well location coordinates and the spatial distribution of the fracture network; Step 2: Divide the control volume of each well into fracture zone and matrix zone, and calculate the pressure and saturation of each sub-region after water injection using the zone material balance equation; Step 3: Calculate the amount of oil absorbed and replaced during the well shut-in stage for each well, and update the saturation of the fracture and matrix areas; Step 4: Calculate the production rate of each well using the seepage model of the fracture network in tight oil reservoirs, and calculate the dynamic interference pressure drop between wells in the well group and correct the production rate using the superposition principle of potential and Newton's iteration. Step 5: Calculate the pressure and saturation of the crack and matrix regions after production based on the zoned material balance equation.
[0006] According to a preferred embodiment of the present invention, in step 1, the parameters of the reservoir, production, and well group include: reservoir length. reservoir width Oil reservoir thickness Porosity Crack porosity Matrix permeability Crack permeability Initial oil saturation Initial water saturation Comprehensive compressibility of the reservoir Matrix compressibility Crack compressibility coefficient Initial formation pressure Crude oil viscosity Water viscosity water density Oil density Water volume coefficient Oil volume coefficient Proportion of cracked areas Relative permeability curves and coordinates of each well location Length of horizontal section of each well Bottom hole pressure of each well Control radius of each well , the radius of each wellbore Injection volume of each well , well simmering time Production time Number of cracks Crack half width Half-length crack .
[0007] According to a preferred embodiment of the present invention, in step 1, the initial control volume of each well, i.e., the boundary of the effective control volume of each well, is determined using the Voronoi partitioning method, and the formula is: ; in, For the first i The plane coordinate vector at the wellhead of a horizontal well; Let m be the initial control volume for each well. 3 ; Let be any point in a two-dimensional plane; This indicates that the domain is a two-dimensional plane; For the first j The plane coordinate vector at the wellhead of a horizontal well; , Represents any well number; For volume.
[0008] According to a preferred embodiment of the present invention, step 2 includes the following specific implementation process: The water saturation of the matrix during the injection stage, derived from the principle of volume balance. Water saturation in cracks and mean formation pressure The calculation formula is: ; ; ; In the formula, To control the volume of a single well, The crack ratio, For crack porosity, For matrix porosity, The initial water saturation level, This refers to the injection volume per well. The volume factor is the water volume coefficient. The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient; Oil saturation Water saturation; The pressure and saturation after water injection include the water saturation of the matrix during the injection phase. Water saturation in cracks and mean formation pressure .
[0009] According to a preferred embodiment of the present invention, step 3 specifically includes the following steps: The amount of oil exchanged during the well shut-in stage was calculated based on the three-dimensional permeation equation. Water saturation in fractures after well sealing Water saturation of the matrix after well steaming The calculation formula is: ; ; ; In the formula, , , , It is the summation index of the three-dimensional series solution in the x, y, and z directions, corresponding to the three spatial directions of the matrix block; D The absorption coefficient is... L The characteristic length of the matrix block. d The thickness of the matrix block; for t Continuous oil change with constant absorption. This represents the water saturation level in the crack area after water injection. This represents the water saturation level of the substrate area after water injection. This refers to the amount of oil replaced due to seepage. The saturation of the fracture and matrix regions is the water saturation of the fractures after well shut-in. Water saturation of the matrix after well sealing .
[0010] According to a preferred embodiment of the present invention, step 4 includes the following specific implementation process: The seepage model of the fracture network in tight oil reservoirs derives the fracture surface source pressure function based on the dual-medium model assumption. The total production is calculated and the production is divided by constructing a production relationship matrix between fractured and horizontal wells; Crack surface source pressure function The formula is: ; In the formula, For point source output, For dimensionless reservoir thickness, This is the symbol for a Bessel function of the second kind. For the Laplace transform variables, For the dimensionless crack half-length, For any point of the crack, without dimension x Direction coordinates The center point of the crack is dimensionless. x Direction coordinates For any point of the crack, without dimension y Direction coordinates The center point of the crack is dimensionless. y Direction coordinates; Crude oil viscosity; The symbol for plane integral is . The variable is the integral variable, along the crack length direction; Permeability along the fracture direction, for x Directional formation permeability; The formula for solving the production relation matrix is: ; In the formula, For the first i The crack is related to the first n The dimensionless pressure drop of the crack, For the first i Dimensionless production of cracks for A Dimensionless production of wells for A Dimensionless bottom hole pressure; Calculate the inter-well interference pressure drop of horizontal wells using the principle of potential superposition. It then returns the production relationship solution matrix for iterative calculation, and calculates the inter-well interference pressure drop. The solution matrix is: ; In the formula, To provide potential at the edge of the reservoir, The potential near each wellbore. The total production of each well. For each wellbore radius, The distance between each well.
[0011] According to a preferred embodiment of the present invention, step 5 includes the following specific implementation process: In each well production stage, the production output is first divided using fracture zone saturation, and the fracture zone saturation, i.e., the pressure and saturation of the fracture region, is then updated. The field changes, the formula is: ; ; ; in, The relative permeability of the oil phase at water saturation in the fracture; The relative permeability of the water phase under the water saturation of the fracture; The total liquid production is obtained from the matrix solution above; the fracture zone volume is... Injection volume of each well Crack porosity Water volume coefficient Oil volume coefficient ; Once the water saturation of the cracks equals that of the matrix, the matrix saturation is used, which is the pressure and saturation of the matrix region. The formula for splitting production and updating the physical field changes in a single well region is as follows: ; ; ; ; In the formula, The relative permeability of the oil phase at the water saturation level of the matrix; The relative permeability of the aqueous phase at the water saturation level of the matrix; The average formation pressure in each well area. For the oil saturation of the matrix zone of each well, The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient, The relative permeability of the oil phase. This is the relative permeability curve of the aqueous phase. For crude oil viscosity, For water viscosity, To increase oil production, This refers to the cumulative water production.
[0012] The beneficial effects of this invention are as follows: This invention proposes a method for predicting the production capacity of a well group in a fractured horizontal well in a tight oil reservoir. This method can effectively consider the impact of inter-well interference on water injection production, realize the updating of the physical field during the water injection process of each well in the well group, and accurately predict the water injection production of the well group. Attached Figure Description
[0013] Figure 1 This is a flowchart of the method for predicting the water injection and huff-and-puff production capacity of a horizontal well group in a tight oil reservoir, as described in this invention. Figure 2 This is a relative permeability curve of a horizontal well group fractured in a tight oil reservoir according to the present invention; Figure 3 This is a schematic diagram of the well location distribution of the horizontal well group for fracturing in tight oil reservoirs according to the present invention; Figure 4 This is a production curve of a horizontal well group fractured in a tight oil reservoir according to the present invention. Figure 5 This is a water production curve of a horizontal well group in a tight oil reservoir fractured according to the present invention. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Unless otherwise specified, all variables in the calculation formulas involved in the solutions are in the International System of Units (SI). Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.
[0015] Example 1 A method for predicting the water injection huff and puff production capacity of a fracturing horizontal well group in a tight oil reservoir, such as Figure 1 As shown, it includes: Step 1: Input the reservoir, production, and well group parameters, and determine the effective control volume boundary of each well based on the well location coordinates and the spatial distribution of the fracture network; Step 2: Divide the control volume of each well into fracture zone and matrix zone, and calculate the pressure and saturation of each sub-region after water injection using the zone material balance equation; Step 3: Calculate the amount of oil absorbed and replaced during the well shut-in stage for each well, and update the saturation of the fracture and matrix areas; Step 4: Calculate the production rate of each well using the seepage model of the fracture network in tight oil reservoirs, and calculate the dynamic interference pressure drop between wells in the well group and correct the production rate using the superposition principle of potential and Newton's iteration. Step 5: Calculate the pressure and saturation of the crack and matrix regions after production based on the zoned material balance equation.
[0016] Example 2 The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir as described in Example 1 differs in that: In step 1, various parameters related to the reservoir, production, and well group are included, such as reservoir length. reservoir width Oil reservoir thickness Porosity Crack porosity Matrix permeability Crack permeability Initial oil saturation Initial water saturation Comprehensive compressibility of the reservoir Matrix compressibility Crack compressibility coefficient Initial formation pressure Crude oil viscosity Water viscosity water density Oil density Water volume coefficient Oil volume coefficient Proportion of cracked areas Relative permeability curves and coordinates of each well location Length of horizontal section of each well Bottom hole pressure of each well Control radius of each well , the radius of each wellbore Injection volume of each well , well simmering time Production time Number of cracks Crack half width Half-length crack .
[0017] In step 1, the initial control volume of each well, i.e., the boundary of the effective control volume of each well, is determined using the Voronoi partitioning method, with the following formula: ; in, For the first i The plane coordinate vector at the wellhead of a horizontal well; Let m be the initial control volume for each well. 3 ; Let be any point in a two-dimensional plane; This indicates that the domain is a two-dimensional plane; For the first j The plane coordinate vector at the wellhead of a horizontal well; , Represents any well number; For volume.
[0018] Taking the development scheme of a fractured horizontal well group in a tight oil reservoir as an example, the reservoir parameters were determined based on field production data. All input parameters after fitting are shown in Table 1 below, and the oil-water permeability curves are as follows. Figure 2 As shown, the development well group consists of three horizontal wells, A, B, and C, as illustrated in the schematic diagram. Figure 3 As shown. Based on the coordinates of the three wells, the controlled volume of well A is calculated to be 4,987,500 m³. 3 Well B has a controlled volume of 4,275,000 m³. 3 The controlled volume of well C is 4,987,500 m³. 3 .
[0019] Table 1. Input parameters for water injection and flushing in well groups; The specific implementation process of step 2 includes: The water saturation of the matrix during the injection stage, derived from the principle of volume balance. Water saturation in cracks and mean formation pressure The calculation formula is: ; ; ; In the formula, To control the volume of a single well, The crack ratio, For crack porosity, For matrix porosity, The initial water saturation level, This refers to the injection volume per well. The volume factor is the water volume coefficient. The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient; Oil saturation Water saturation; The pressure and saturation after water injection include the water saturation of the matrix during the injection phase. Water saturation in cracks and mean formation pressure .
[0020] The controlled volume of each well is divided into a fracture zone and a matrix zone; this means that the complex fracture network formed after fracturing is the modified zone, while the unmodified original reservoir is the matrix zone. The fracture zone is mainly affected by the fracture half-length, fracture half-width, and number of fractures. The crack ratio determines the size of the crack zone volume; the crack zone volume matrix volume .
[0021] The water saturation of each well after water injection is divided into matrix saturation and fracture saturation. The matrix water saturation of well A is calculated based on the formula. The water saturation of the crack is 0.47. The mean formation pressure is 0.96. The pressure is 15.98 MPa; the matrix water saturation of well B is... The water saturation of the crack is 0.47. The mean formation pressure is 0.972. The pressure is 16.01 MPa. The water saturation of the matrix in well C is... The water saturation of the crack is 0.47. The mean formation pressure is 0.96. It is 15.98 MPa.
[0022] The specific implementation process of step 3 includes: The amount of oil exchanged during the well shut-in stage was calculated based on the three-dimensional permeation equation. Water saturation in fractures after well sealing Water saturation of the matrix after well steaming The calculation formula is: ; ; ; In the formula, , , , It is the summation index (series term number, i.e., eigenvalue order / modal number) of the three-dimensional series solution in the x, y, and z directions, corresponding to the three spatial directions of the matrix block; D The absorption coefficient is... L The characteristic length of the matrix block. d The thickness of the matrix block; for t Continuous oil change with constant absorption. This represents the water saturation level in the crack area after water injection. This represents the water saturation level of the substrate area after water injection. For the amount of oil replaced by absorption; and Synonyms, the subscript t only indicates time.
[0023] The saturation of the fracture and matrix regions is the water saturation of the fractures after well shut-in. Water saturation of the matrix after well sealing .
[0024] The amount of oil exchanged through well A after 30 days of well shut-in was calculated based on the three-dimensional permeation equation. It is 246.36m 3 Water saturation in the cracks after well sealing The matrix water saturation was 0.626 after well steaming. The value is 0.47; the oil exchange rate of well B is [missing information]. It is 246.36m 3 Water saturation in the cracks after well sealing The water saturation of the matrix after well steaming is 0.651. The value is 0.47; the oil exchange rate of well C is [missing information]. It is 246.36m 3 Water saturation in the cracks after well sealing The matrix water saturation was 0.626 after well steaming. It is 0.47.
[0025] The specific implementation process of step 4 includes: The seepage model of the fracture network in tight oil reservoirs is as follows: the fracture network of the fractured horizontal well is discretized into several fracture segments (line sources). Based on the dual medium assumption, the pressure response function of the fracture surface source in the Laplace domain is derived. The pressure response of all fracture segments is superimposed using the superposition principle to construct the production relationship matrix of "fracture-fracture, fracture-wellbore". The production of each fracture segment is solved by the matrix and accumulated to obtain the production of each well.
[0026] The seepage model of the fracture network in tight oil reservoirs derives the fracture surface source pressure function based on the dual-medium model assumption. The total production is calculated and the production is divided by constructing a production relationship matrix between fractured and horizontal wells; Crack surface source pressure function The formula is: ; In the formula, For point source output, For dimensionless reservoir thickness, This is the symbol for a Bessel function of the second kind. For the Laplace transform variables, For the dimensionless crack half-length, For any point of the crack, without dimension x Direction coordinates The center point of the crack is dimensionless. x Direction coordinates For any point of the crack, without dimension y Direction coordinates The center point of the crack is dimensionless. y Direction coordinates; Crude oil viscosity; The symbol for plane integral is . The variable is the integral variable, along the crack length direction; Permeability along the fracture direction, for x Directional formation permeability; The Warren-Root dual-medium model is a classic model describing flow in fractured / tight reservoirs. It assumes the reservoir consists of two overlapping, continuous media systems: a matrix system (high porosity, low permeability, primarily serving as oil storage) and a fracture system (high permeability, low porosity, primarily serving as a conduit). Channeling (quasi-steady or unsteady state) exists between the matrix and fractures; fluid flows from the matrix into the fractures and then into the wellbore. The model characterizes the coupling between the two systems using the reservoir capacity ratio ω and the channeling coefficient λ.
[0027] The formula for solving the production relation matrix is: ; In the formula, For the first i The crack is related to the first n The dimensionless pressure drop of the crack, For the first i Dimensionless production of cracks for A Dimensionless production of wells for A Dimensionless bottom hole pressure; The production production relation solution matrix corresponds to the application result of the fracture surface pressure function mentioned above. From the fracture surface pressure function, the pressure drop generated by each fracture at any location can be obtained. By superimposing the pressure drop responses of all fracture segments, the response relationship between fracture pressure drop and fracture production is established. This relationship can be written in matrix form as the production production relation solution matrix. The matrix calculation result is the production of each fracture. After summing, the single-well production is obtained.
[0028] Calculate the inter-well interference pressure drop of horizontal wells using the principle of potential superposition. It then returns the production relationship solution matrix for iterative calculation, and calculates the inter-well interference pressure drop. The solution matrix is: ; In the formula, To provide potential at the edge of the reservoir, The potential near each wellbore. The total production of each well. For each wellbore radius, The distance between each well.
[0029] During the iteration process, the initial production rate of each well is obtained by solving the production relationship matrix, and then substituted into the inter-well interference pressure drop solution matrix to calculate the interference pressure drop. and will Returning to the production relationship matrix for each well, taking well A as an example, the dimensionless bottom hole pressure expression for well A in its right-hand vector is: In the formula For crack permeability, For reservoir thickness, For crude oil viscosity, To represent the average formation pressure, For the bottom hole pressure, This serves as a reference production rate. We then return to the production relationship matrix for each well and recalculate the production rate for each well to correct for the output of each well.
[0030] Model simulations showed that on the first day of production, the total daily production of well A was 139.01 m³. 3 / d, the total daily production of well B is 89.46m 3 / d, the total daily production of well C is 63.06m 3 / d.
[0031] According to a preferred embodiment of the present invention, step 5 includes the following specific implementation process: In each well production stage, the production output is first divided using fracture zone saturation, and the fracture zone saturation, i.e., the pressure and saturation of the fracture region, is then updated. The field changes, the formula is: ; ; ; in, The relative permeability of the oil phase at water saturation in the fracture; The relative permeability of the water phase under the water saturation of the fracture; The total liquid production is obtained from the matrix solution above; the fracture zone volume is... Injection volume of each well Crack porosity Water volume coefficient Oil volume coefficient ; Once the water saturation of the cracks equals that of the matrix, the matrix saturation is used, which is the pressure and saturation of the matrix region. The formula for splitting production and updating the physical field changes in a single well region is as follows: ; ; ; ; In the formula, The relative permeability of the oil phase at the water saturation level of the matrix; The relative permeability of the aqueous phase at the water saturation level of the matrix; The average formation pressure in each well area. For the oil saturation of the matrix zone of each well, The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient, The relative permeability of the oil phase. This is the relative permeability curve of the aqueous phase. For crude oil viscosity, For water viscosity, To increase oil production, This refers to the cumulative water production.
[0032] Based on the zonal material balance equation, after 17 days of production, the fracture and matrix saturation levels in well A, 23 days in well B, and 38 days in well C were equal. After 400 days, the average formation pressure in the well A control zone decreased to 6.08 MPa, and the matrix oil saturation decreased to 0.488. In the well B control zone, the average formation pressure decreased to 8.54 MPa, and the matrix oil saturation decreased to 0.4983. In the well C control zone, the average formation pressure decreased to 11.4 MPa, and the matrix oil saturation decreased to 0.5108. The daily oil production curves for each well are as follows. Figure 4 As shown, the daily water production curves of each well are as follows: Figure 5 As shown.
Claims
1. A method for predicting the water injection huff and puff production capacity of a fracturing horizontal well group in a tight oil reservoir, characterized in that, include: Step 1: Input the reservoir, production, and well group parameters, and determine the effective control volume boundary of each well based on the well location coordinates and the spatial distribution of the fracture network; Step 2: Divide the control volume of each well into fracture zone and matrix zone, and calculate the pressure and saturation of each sub-region after water injection using the zone material balance equation; Step 3: Calculate the amount of oil absorbed and replaced during the well shut-in stage for each well, and update the saturation of the fracture and matrix areas; Step 4: Calculate the production rate of each well using the fracture network seepage model for tight oil reservoirs. Calculate the dynamic interference pressure drop between wells in the well group and correct the production rate using the superposition principle of potentials and Newton's iteration. This includes: deriving the fracture surface pressure function based on the dual-medium model assumption of the fracture network seepage model for tight oil reservoirs; solving for the total production rate and dividing the production rate by constructing a production relationship matrix between fractures and horizontal wells; calculating the interference pressure drop between horizontal wells using the superposition principle of potentials and returning the production relationship solution matrix for iterative calculation. Step 5: Calculate the pressure and saturation of the crack and matrix regions after production based on the zoned material balance equation.
2. The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to claim 1, characterized in that, In step 1, various parameters related to the reservoir, production, and well group are included, such as reservoir length. reservoir width Oil reservoir thickness Porosity Crack porosity Matrix permeability Crack permeability Initial oil saturation Initial water saturation Comprehensive compressibility of the reservoir Matrix compressibility Crack compressibility coefficient Initial formation pressure Crude oil viscosity Water viscosity water density Oil density Water volume coefficient Oil volume coefficient Proportion of cracked areas Relative permeability curves and coordinates of each well location Length of horizontal section of each well Bottom hole pressure of each well Control radius of each well , the radius of each wellbore Injection volume of each well , well simmering time Production time Number of cracks Crack half width Half-length crack .
3. The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to claim 1, characterized in that, In step 1, the initial control volume of each well, i.e., the boundary of the effective control volume of each well, is determined using the Voronoi partitioning method, with the following formula: ； in, For the first i The plane coordinate vector at the wellhead of a horizontal well; Let m be the initial control volume for each well. 3 ; Let be any point in a two-dimensional plane; This indicates that the domain is a two-dimensional plane; For the first j The plane coordinate vector at the wellhead of a horizontal well; , Represents any well number; For volume.
4. The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to claim 1, characterized in that, The specific implementation process of step 2 includes: The water saturation of the matrix during the injection stage, derived from the principle of volume balance. Water saturation in cracks and mean formation pressure The calculation formula is: ； ； ； In the formula, To control the volume of a single well, The crack ratio, For crack porosity, For matrix porosity, The initial water saturation level, This refers to the injection volume per well. The volume factor is the water volume coefficient. The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient; Oil saturation Water saturation; The pressure and saturation after water injection include the water saturation of the matrix during the injection phase. Water saturation in cracks and mean formation pressure .
5. The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to claim 1, characterized in that, The specific implementation process of step 3 includes: The amount of oil exchanged during the well shut-in stage was calculated based on the three-dimensional permeation equation. Water saturation in fractures after well sealing Water saturation of the matrix after well steaming The calculation formula is: ； ； ； In the formula, , , , It is the summation index of the three-dimensional series solution in the x, y, and z directions, corresponding to the three spatial directions of the matrix block; D The absorption coefficient is... L The characteristic length of the matrix block. d The thickness of the matrix block; for t Continuous oil change with constant absorption. This represents the water saturation level in the crack area after water injection. This represents the water saturation level of the substrate area after water injection. This refers to the amount of oil replaced due to seepage. The saturation of the fracture and matrix regions is the water saturation of the fractures after well shut-in. Water saturation of the matrix after well sealing .
6. The method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to claim 1, characterized in that, The specific implementation process of step 4 includes: The seepage model of the fracture network in tight oil reservoirs derives the fracture surface source pressure function based on the dual-medium model assumption. The total production is calculated and the production is divided by constructing a production relationship matrix between fractured and horizontal wells; Crack surface source pressure function The formula is: ； In the formula, For point source output, For dimensionless reservoir thickness, This is the symbol for a Bessel function of the second kind. For the Laplace transform variables, For the dimensionless crack half-length, For any point of the crack, without dimension x Direction coordinates The center point of the crack is dimensionless. x Direction coordinates For any point of the crack, without dimension y Direction coordinates The center point of the crack is dimensionless. y Direction coordinates; Crude oil viscosity; The symbol for plane integral is . The variable is the integral variable, along the crack length direction; Permeability along the fracture direction, for x Directional formation permeability; The formula for solving the production relation matrix is: ； In the formula, For the first i The crack is related to the first n The dimensionless pressure drop of the crack, For the first i Dimensionless production of cracks for A Dimensionless production of wells for A Dimensionless bottom hole pressure; Calculate the inter-well interference pressure drop of horizontal wells using the principle of potential superposition. It then returns the production relationship solution matrix for iterative calculation, and calculates the inter-well interference pressure drop. The solution matrix is: ； In the formula, To provide potential at the edge of the reservoir, The potential near each wellbore. The total production of each well. For each wellbore radius, The distance between each well.
7. A method for predicting the water injection and huff-and-puff production capacity of a fractured horizontal well group in a tight oil reservoir according to any one of claims 1-6, characterized in that, The specific implementation process of step 5 includes: In each well production stage, the production output is first divided using fracture zone saturation, and the fracture zone saturation, i.e., the pressure and saturation of the fracture region, is then updated. The field changes, the formula is: ； ； ； in, The relative permeability of the oil phase at water saturation in the fracture; The relative permeability of the water phase under the water saturation of the fracture; The total liquid production is obtained from the matrix solution above; the fracture zone volume is... Injection volume of each well Crack porosity Water volume coefficient Oil volume coefficient ; Once the water saturation of the cracks equals that of the matrix, the matrix saturation is used, which is the pressure and saturation of the matrix region. The formula for splitting production and updating the physical field changes in a single well region is as follows: ； ； ； ； In the formula, The relative permeability of the oil phase at the water saturation level of the matrix; The relative permeability of the aqueous phase at the water saturation level of the matrix; The average formation pressure in each well area. For the oil saturation of the matrix zone of each well, The crack compressibility coefficient is denoted as . The matrix compressibility coefficient, The compression coefficient of crude oil. The water compressibility coefficient, The relative permeability of the oil phase. This is the relative permeability curve of the aqueous phase. For crude oil viscosity, For water viscosity, To increase oil production, This refers to the cumulative water production.