Regional in-situ stress calculation method, deep coal seam in-situ stress calculation method and device

Abstract

A regional in-situ stress calculation method, a deep coal seam in-situ stress calculation method and a device. The deep coal seam in-situ stress calculation method comprises: on the basis of structural feature data of a preset area surrounding a target well location in a target block structural map, performing fitting to generate a quadratic surface; determining physical parameters of a target stratum, and, on the basis of the physical parameters and the quadratic surface, separately calculating horizontal in-situ stress components caused by vertical in-situ stress, horizontal in-situ stress components caused by a macrostructure and horizontal in-situ stress components caused by a microstructure; by taking the directions of the horizontal in-situ stress components caused by the microstructure as basis axes, decomposing the horizontal in-situ stress components caused by the vertical in-situ stress and the horizontal in-situ stress components caused by the macrostructure onto the basis axis directions, so as to establish an analysis equation; and, on the basis of the analysis equation, calculating structural stress coefficients, and, on the basis of the structural stress coefficients, rock mechanics parameters and a stratum pressure, calculating a horizontal in-situ stress magnitude and direction of the target well location.

Description

Regional ground stress calculation method, deep coal seam ground stress calculation method and device

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202311636132.9 filed on November 30, 2023, and cites the contents disclosed in the above patent application as part of this application. Technical Field

[0003] The present application relates to the field of in-situ stress inversion for unconventional reservoirs, and in particular to a method and device for calculating regional in-situ stress, and a method and device for calculating in-situ stress for deep coal seams. Background Art

[0004] In the current oil and gas exploration landscape, deep coalbed methane resources are abundant but relatively underdeveloped, presenting broad prospects for exploration and development. Deep coalbed methane reservoirs are dense, requiring horizontal wells and fracturing techniques for production. In-situ stress is a key factor controlling fracturing in coal reservoirs. Its combined characteristics control the extension and propagation of induced fractures, ultimately determining the effectiveness of fracturing.

[0005] The magnitude of geostress is primarily influenced by factors such as tectonic movement and the weight of the overlying rock. Commonly used methods for calculating geostress include the Huang model, the isotropic model, and the transversely isotropic model. The Huang model posits that geostress is primarily caused by overlying rock pressure and horizontal tectonic stress, with horizontal tectonic stress being proportional to overlying rock pressure.

[0006] The isotropic model assumes that the rock is a homogeneous, isotropic linear elastic body, and assumes that during the geological tectonic movement in the late sedimentary period, there is no relative displacement between the strata, and the strains in both horizontal directions of all strata are constant.

[0007] The transversely isotropic model was first applied to the in-situ stress evaluation of the Baxter shale reservoir and achieved good results in tight sandstone reservoirs.

[0008] The limitations of the above models are: (1) Although the common geostress calculation method takes into account the influence of tectonic movement, it considers a uniform macro-tectonic action. There is only one set of tectonic stress coefficients for a large area, and the geostress calculation method does not consider the influence of the size and direction of the local structural surface curvature. In fact, tectonic movement will form local positive structures, negative structures and slopes and other microstructures in different areas within the macrostructure. The size and direction of geostress in different microstructure areas are significantly different. (2) Since there is only one set of tectonic stress coefficients for a large area, similar to deep coal seams, because they are horizontal wells, there is no well logging or well logging data is scarce. When inferring the geostress at other well locations without well logging data based on known well location data, there is no constraint of well logging data. The calculation error will become larger and larger during the inference process.

[0009] Therefore, the industry urgently needs to establish a geostress calculation method that takes into account local microstructural characteristics and accurately describes geostress.

[0010] Summary of the Invention

[0011] The purpose of this application is to provide a regional ground stress calculation method, a deep coal seam ground stress calculation method and an apparatus, and to provide support for subsequent fracturing scheme design and optimization research based on local microstructural characteristics.

[0012] To achieve the above-mentioned purpose, the present application provides a method for calculating the geostress of deep coal seams, which specifically includes: fitting and generating a quadratic surface based on the structural characteristic data of a preset area around a target well location in a structural map of a target block; determining the physical parameters of the target layer by acquiring well logging data and indoor experimental data, and calculating the horizontal geostress component caused by vertical geostress, the horizontal geostress component caused by macroscopic structure, and the horizontal geostress component caused by microscopic structure based on the physical parameters and the quadratic surface; taking the direction of the horizontal geostress component caused by microscopic structure as the basic axis, decomposing the horizontal geostress component caused by vertical geostress and the horizontal geostress component caused by macroscopic structure in the direction of the basic axis to establish an analytical equation including a macroscopic structural stress coefficient and a microscopic structural stress coefficient; calculating the structural stress coefficient based on the analytical equation, and calculating the magnitude and direction of the horizontal geostress of the target well location by using the structural stress coefficient, rock mechanics parameters, and formation pressure.

[0013] In one embodiment, optionally, the structural characteristic data of the preset area around the target well location in the target block structural map also includes: extracting the structural characteristic parameters of the preset area around the target well location through the target block structural map to obtain longitude, latitude and elevation data; converting the longitude, latitude and elevation data into geodetic coordinate data, and converting the geodetic coordinate data into coordinate information under a rectangular coordinate system; generating a quadratic surface by fitting the coordinate information, and obtaining the coefficients of two quadratic terms and a cross term based on the quadratic surface.

[0014] In one embodiment, optionally, the physical parameters include static rock mechanics data of the target layer, formation pressure of the target layer and vertical geostress of the target layer; wherein, the static rock mechanics data of the target layer is determined by well logging and indoor experiments; the formation pressure of the target layer is obtained based on injection pressure drop test data; and the vertical geostress of the target layer is calculated using density logging data.

[0015] In one embodiment, optionally, the static rock mechanics data includes elastic modulus, Poisson's ratio, tensile strength and effective stress coefficient.

[0016] In one embodiment, optionally, calculating the horizontal geostress component caused by the vertical geostress based on the physical parameters and the quadratic surface includes: calculating the horizontal geostress component caused by the vertical geostress through the vertical geostress of the target layer, the formation pressure and the corresponding Poisson's ratio and the effective stress coefficient.

[0017] In one embodiment, optionally, calculating the horizontal geostress components caused by the macro structure based on the physical parameters and the quadratic surface includes: constructing a macro equation containing a macro structure coefficient through the vertical geostress, formation pressure and corresponding effective stress coefficient of the target layer; and calculating the horizontal geostress components caused by the macro structure based on the macro equation.

[0018] In one embodiment, optionally, calculating the horizontal ground stress components caused by the microstructure based on the physical parameters and the quadratic surface respectively includes: constructing a micro equation containing microstructure coefficients using the elastic modulus, Poisson's ratio and coefficients of the quadratic term and the cross term of the target layer; and calculating the horizontal ground stress components caused by the microstructure through the micro equation.

[0019] In one embodiment, optionally, taking the direction of the horizontal geostress component caused by the microstructure as the basic axis further includes: determining the direction of the horizontal geostress caused by the macrostructure by averaging the multipole array acoustic logging data of multiple wells in the target area; determining the direction of the horizontal geostress caused by the microstructure by calculating the structural and rock mechanics data, and then determining the final geostress direction.

[0020] In one embodiment, optionally, the horizontal stress component caused by the vertical stress and the horizontal stress component caused by the macro structure are decomposed into the direction of the basic axis to establish an analytical equation including a macro structure stress coefficient and a micro structure stress coefficient, which includes: based on the fact that the horizontal stress system caused by the vertical stress, the horizontal stress system caused by the macro structure, and the horizontal stress system caused by the micro structure are the same, the horizontal stress component caused by the vertical stress, the horizontal stress component caused by the macro structure, and the horizontal stress component caused by the micro structure are jointly established to establish an analytical equation including a macro structure stress coefficient and a micro structure stress coefficient.

[0021] In one embodiment, optionally, calculating and obtaining the tectonic stress coefficient according to the analytical equation includes: obtaining the tectonic stress coefficient by solving the analytical equation by least squares fitting.

[0022] The present application also provides a regional geostress calculation method including a deep coal seam geostress calculation method, the method comprising: obtaining a curvature value according to a structural map of a target block, and dividing the target block into multiple regions according to the curvature value; calculating the horizontal geostress magnitude and direction of each well location in the region by the deep coal seam geostress calculation method to obtain corresponding geostress information; and obtaining geostress distribution data of the target block according to the geostress information.

[0023] In one embodiment, optionally, dividing the target block into multiple areas according to the curvature value further includes: when the difference between the structural feature data of two adjacent areas is greater than a preset threshold and there is no known well in the transition area between the two areas, constructing a virtual well in the transition area.

[0024] The present application also provides a deep coal seam geostress calculation device, which includes a fitting module, a calculation module, a construction module and an analysis module; the fitting module is used to fit and generate a quadratic surface based on the structural feature data of a preset area around a target well location in a target block structural map; the calculation module is used to determine the physical parameters of the target layer through logging data and indoor experimental data, and calculate the horizontal geostress component caused by vertical geostress, the horizontal geostress component caused by macroscopic structure, and the horizontal geostress component caused by microscopic structure based on the physical parameters and the quadratic surface; the construction module is used to decompose the horizontal geostress component caused by vertical geostress and the horizontal geostress component caused by macroscopic structure in the direction of the basic axis with the direction of the horizontal geostress component caused by microscopic structure as the basic axis, and establish an analytical equation including a macroscopic structural stress coefficient and a microscopic structural stress coefficient; the analysis module is used to calculate the structural stress coefficient based on the analytical equation, and calculate the magnitude and direction of the horizontal geostress at the target well location through the structural stress coefficient, rock mechanics parameters and formation pressure.

[0025] The present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method when executing the computer program.

[0026] The present application also provides a computer-readable storage medium, which stores a computer program for executing the above method.

[0027] The present application also provides a computer program product, comprising a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0028] The beneficial technical effect of the present application is that the magnitude and direction of the ground stress of multiple wells can be calculated when the logging data is limited, and the prediction results are highly accurate. Coal reservoir fracturing transformation can be carried out according to the ground stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application, constitute a part of the present application, and do not constitute a limitation of the present application. In the drawings:

[0030] FIG1 is a schematic flow chart of a method for calculating in-situ stress in deep coal seams according to an embodiment of the present application;

[0031] FIG2 is a schematic diagram of a quadratic surface fitting process provided by an embodiment of the present application;

[0032] FIG3 is a schematic diagram of a quadratic surface provided in an embodiment of the present application;

[0033] FIG4 is a flow chart of a method for calculating regional geostress provided in one embodiment of the present application;

[0034] FIG5 is a schematic structural diagram of a deep coal seam ground stress calculation device provided in one embodiment of the present application;

[0035] FIG6 is a diagram of a target block structure and a schematic diagram of structural partitions provided in one embodiment of the present application;

[0036] FIG7 is a schematic diagram of microstructure area division provided in one embodiment of the present application;

[0037] FIG8 is a schematic structural diagram of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0038] The following will describe in detail the implementation methods of this application in conjunction with the accompanying drawings and examples, so that the application can fully understand how technical means are used to solve technical problems and achieve technical effects, and implement them accordingly. It should be noted that as long as there is no conflict, the various embodiments and the various features in each embodiment of this application can be combined with each other, and the resulting technical solutions are all within the scope of protection of this application.

[0039] Additionally, the steps shown in the flowcharts of the accompanying drawings may be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in an order different from that shown.

[0040] Referring to FIG1 , the present application provides a method for calculating in-situ stress in deep coal seams, specifically comprising:

[0041] S101 generates a quadratic surface by fitting according to structural characteristic data of a preset area around a target well location in a target block structural map;

[0042] S102 determines the physical parameters of the target layer using well logging data and indoor experimental data, and calculates the horizontal in-situ stress components caused by vertical in-situ stress, the horizontal in-situ stress components caused by macroscopic structures, and the horizontal in-situ stress components caused by microscopic structures based on the physical parameters and the quadratic surface;

[0043] S103 takes the direction of the horizontal geostress component caused by the microstructure as the base axis, decomposes the horizontal geostress component caused by the vertical geostress and the horizontal geostress component caused by the macrostructure into the direction of the base axis, and establishes an analytical equation including the macrostructure stress coefficient and a microstructure stress coefficient;

[0044] S104 calculates the tectonic stress coefficient according to the analytical equation, and calculates the magnitude and direction of the horizontal ground stress at the target well location using the tectonic stress coefficient, rock mechanics parameters, and formation pressure.

[0045] Among them, the physical parameters include the static rock mechanics data of the target layer, the formation pressure of the target layer and the vertical geostress of the target layer; among them, the static rock mechanics data of the target layer is determined by well logging and indoor experiments; the formation pressure of the target layer is obtained according to the injection pressure drop test data; the vertical geostress of the target layer is calculated using the density logging data; the static rock mechanics data includes elastic modulus, Poisson's ratio, tensile strength and effective stress coefficient. Specifically, the deep coal seam geostress calculation method provided in this application is based on the structural curvature near the well location and virtual well technology, and divides the target area into several micro-structural zones. Each structural zone has different micro-structural coefficients. Starting from the area with the most known wells, the geostress magnitude and direction of the entire area can be calculated by outward deduction. The method comprises the following steps: extracting structural characteristic data near the target well location according to the structural map of the target block, and fitting a quadratic surface using the extracted data; determining the static rock mechanics data of the target layer by combining well logging data with indoor experiments; determining the formation pressure of the target layer by using injection / pressure drop test data; calculating the vertical geostress of the target layer by using density logging data; respectively calculating the horizontal geostress component caused by the vertical stress of the layer, the horizontal geostress component caused by the macro structure, and the horizontal geostress component caused by the micro structure; determining the direction of each stress component, taking the horizontal geostress direction caused by the micro structure as the basic axis, decomposing the horizontal geostress components in other directions into this direction, and establishing an equation containing two macro structural stress coefficients and one micro structural stress coefficient; solving the equation to determine three structural stress coefficients; and calculating the magnitude and direction of the horizontal geostress at the well location by using the structural stress coefficient, rock mechanics parameters and formation pressure.

[0046] Referring to FIG. 2 , in one embodiment, the structural characteristic data of the preset area around the target well location in the target block structural map further includes:

[0047] S201 extracts structural characteristic parameters of a preset area around the target well location through the target block structural map to obtain latitude, longitude and elevation data;

[0048] S202 converts the longitude, latitude and elevation data into geodetic coordinate data, converting the geodetic coordinate data into coordinate information in a rectangular coordinate system;

[0049] S203 generates a quadratic surface by fitting the coordinate information, and obtains coefficients of two quadratic terms and a cross term based on the quadratic surface.

[0050] Specifically, in actual work, the structural characteristic data mentioned above is mainly obtained by extracting the structural characteristic parameters near the target well location using a structural map after selecting the target well area. The extracted latitude, longitude and elevation data also need to be coordinate converted, and then the geodetic coordinates are converted to XYZ coordinates in a rectangular coordinate system (as shown in Table 1 below) to facilitate the subsequent surface fitting. The extracted data is used to fit a quadratic surface, as shown in Figure 3, and the coefficients of the two quadratic terms and the cross term are determined.

[0051] Table 1

[0052] Where: ω(x, y) = -0.02273x² + 0.05687y² - 0.0339xy + 81.09x - 609.2y + 1544000;

[0053] In one embodiment of the present application, calculating the horizontal geostress component caused by the vertical geostress based on the physical parameters and the quadratic surface includes: calculating the horizontal geostress component caused by the vertical geostress through the vertical geostress of the target layer, the formation pressure and the corresponding Poisson's ratio and the effective stress coefficient.

[0054] The specific calculation formula is as follows:

[0055] in, are the maximum and minimum horizontal stress components caused by vertical stress, MPa; ν is Poisson's ratio, dimensionless; σ V is the vertical ground stress, MPa; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0056] In another embodiment of the present application, the horizontal geostress components caused by the macro structure are calculated based on the physical parameters and the quadratic surface, including: constructing a macro equation containing the macro structure coefficient through the vertical geostress of the target layer, the formation pressure and the corresponding effective stress coefficient; and calculating the horizontal geostress components caused by the macro structure according to the macro equation.

[0057] The specific calculation formula is as follows:

[0058] in, are the maximum and minimum horizontal stress components caused by macrostructure, MPa; β1 and β2 are macrostructure coefficients, dimensionless; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0059] In another embodiment of the present application, the horizontal ground stress components caused by the microstructure are calculated based on the physical parameters and the quadratic surface, including: constructing a micro equation containing microstructure coefficients using the elastic modulus, Poisson's ratio, and coefficients of quadratic terms and cross terms of the target layer; and obtaining the horizontal ground stress components caused by the microstructure through the micro equation.

[0060] The specific calculation formula is as follows:

[0061] in, are the ground stress components caused by microstructure, MPa; ν is Poisson's ratio, dimensionless; E is elastic modulus, MPa; β3 is macrostructure coefficient, dimensionless; a, b, c are the x values ​​in the fitted quadratic surface equation. 2 ,y 2 and the coefficients of the xy terms, dimensionless.

[0062] In one embodiment, taking the direction of the horizontal geostress component caused by the microstructure as the basic axis further includes: determining the direction of the horizontal geostress caused by the macrostructure by using the average value of multiple wells in the target area; determining the direction of the horizontal geostress caused by the microstructure by calculating the structural and rock mechanics data; and determining the actual geostress direction using multipole array acoustic logging data.

[0063] On this basis, the direction of each stress component can be determined, and then the horizontal geostress direction caused by the microstructure is used as the basic axis, and the horizontal geostress components in other directions are decomposed into this direction, and an equation containing two macro-tectonic stress coefficients and one micro-tectonic stress coefficient is established; further, the horizontal geostress component caused by the vertical geostress and the horizontal geostress component caused by the macrostructure are decomposed into the basic axis direction to establish an analytical equation containing the macro-tectonic stress coefficient and one micro-tectonic stress coefficient, which may include: based on the horizontal geostress system caused by the vertical geostress, the horizontal geostress system caused by the macrostructure, and the horizontal geostress system caused by the microstructure being the same, the horizontal geostress component caused by the vertical geostress, the horizontal geostress component caused by the macrostructure, and the horizontal geostress component caused by the microstructure are jointly established to contain the macro-tectonic stress coefficient and one micro-tectonic stress coefficient.

[0064] Specifically, corresponding component equations are established for wells X1 and X2. Since these two wells are located in the same wellbore area, their corresponding tectonic stress coefficients β1, β2, and β3 can be assumed to be the same. After determining the horizontal in-situ stress components caused by vertical stress, the horizontal in-situ stress components caused by macrostructures, and the horizontal in-situ stress components caused by microstructures, the simultaneous equations are established.

[0065] Among them, σ x1 ,σ y1 , τ xy1 are the two normal stress components and the shear stress component, MPa; are the stress components caused by vertical stress, macrostructure, and local microstructure, MPa, respectively.

[0066] After constructing the above analytical equations, the tectonic stress coefficients can be obtained by solving the analytical equations using least squares fitting. Specifically, the three tectonic stress coefficients are determined. Because the number of equations exceeds the number of unknowns, the solution obtained is a least squares fitting solution. After the three tectonic stress coefficients are determined, the coefficients are substituted back into the formula, the difference between the actual values ​​and the fitted values ​​is compared, and a quantitative analysis is performed. The data in Table 2 shows that the prediction error of this method is less than 10%. It has high reliability. Subsequently, the tectonic stress coefficients, rock mechanical parameters, and formation pressure are used to calculate the magnitude and direction of horizontal stress at other wells in the area (well X3).

[0067] Table 2

[0068] To facilitate a clearer understanding of the deep coal seam in-situ stress calculation method provided by the present application, the following generally describes the implementation steps of the deep coal seam in-situ stress calculation method in conjunction with the aforementioned embodiments. Persons skilled in the art will appreciate that this description does not limit the implementation of the present application. The specific steps of the deep coal seam in-situ stress calculation method of the present application are as follows:

[0069] Step 1: Extract structural characteristic data near the target well location based on the structural map of the target block, fit a quadratic surface using the extracted data, and determine the coefficients of the two quadratic terms and the cross term;

[0070] Step 2: Determine the static rock mechanics data of the target layer through well logging combined with laboratory experiments, including elastic modulus, Poisson's ratio, tensile strength, and effective stress coefficient; and determine the formation pressure of the target layer using injection / pressure drop test data.

[0071] Step 3: Calculate the vertical in-situ stress of the target layer using density logging data;

[0072] Step 4: Using the vertical in-situ stress, formation pressure, Poisson's ratio, and effective stress coefficient of the target layer, calculate the horizontal in-situ stress component caused by the vertical stress of the layer. The specific calculation formula is as follows:

[0073] in, are the maximum and minimum horizontal stress components caused by vertical stress, MPa; ν is Poisson's ratio, dimensionless; σ V is the vertical ground stress, MPa; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0074] Step 5: Using the vertical in-situ stress, formation pressure, and effective stress coefficient of the target layer, calculate the horizontal in-situ stress component caused by the macrostructure of the layer and obtain an equation containing the macrostructure coefficient. The specific calculation formula is as follows:

[0075] in, are the maximum and minimum horizontal stress components caused by macrostructure, MPa; β1 and β2 are macrostructure coefficients, dimensionless; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0076] Step 6: Using the elastic modulus, Poisson's ratio, and structural data (curvature) of the target horizon, calculate the horizontal stress component caused by the microstructure of the horizon and obtain an equation containing the microstructure coefficient. The specific calculation formula is as follows:

[0077] in, are the ground stress components caused by microstructure, MPa; ν is Poisson's ratio, dimensionless; E is elastic modulus, MPa; β3 is macrostructure coefficient, dimensionless; a, b, c are the x values ​​in the fitted quadratic surface equation. 2 ,y 2 and the coefficients of the xy terms, dimensionless.

[0078] Step 7: Determine the direction of each stress component. The horizontal stress component caused by vertical stress is equal in all directions. The direction of horizontal stress caused by macrostructure is determined by averaging multipole array acoustic logging data from multiple wells in the target area. The direction of horizontal stress caused by microstructure is calculated using the two-dimensional stress components and shear stress.

[0079] Where θ is the angle between the microscopic maximum principal stress component and the x-axis; are the maximum and minimum horizontal stress components caused by microstructure, MPa; Maximum principal stress corresponding to the microstructure, MPa;

[0080] The final maximum principal stress direction can be obtained by the following formula of the resultant force and shear stress in the xy direction.

[0081] in, is the angle between the maximum principal stress direction and the x-axis; σ x ,σ y are the sum of the stress components in the x and y directions, τ xy is the shear stress in the xy plane, MPa;

[0082] Step 8: Taking the horizontal geostress direction caused by microstructure as the basic axis, decompose the horizontal geostress components in other directions into this direction, and establish an equation containing two macrostructure stress coefficients and one microstructure stress coefficient;

[0083] Step 9: Solve equation (8) to determine the three tectonic stress coefficients. Since the number of equations exceeds the number of unknowns, the solution obtained is the least squares fitting solution.

[0084] Referring to FIG4 , the present application further provides a regional ground stress calculation method including a deep coal seam ground stress calculation method, the method comprising:

[0085] S401 obtains a curvature value according to a target block structure diagram, and divides the target block into multiple areas according to the curvature value;

[0086] S402 calculates the horizontal ground stress magnitude and direction of each well location in the area using a deep coal seam ground stress calculation method to obtain corresponding ground stress information;

[0087] S403 obtains the ground stress distribution data of the target block according to the ground stress information.

[0088] Partitioning the target area into multiple regions according to the curvature value further includes constructing a virtual well in the transition region when a difference between structural feature data of two adjacent regions is greater than a preset threshold and there is no known well in the transition region between the two regions.

[0089] The geostress distribution of the target area can be determined based on the magnitude and direction of the horizontal geostress of each well determined by the calculation method of the above embodiment; specifically, first, based on the structural map, use geological software to read the curvature value; divide the area into several small areas according to the curvature value (the curvature value is positive, negative and zero), and the micro-tectonic stress coefficient of each area is different. It should be pointed out in particular that when partitioning, if the area is too large, it is easy to cause low calculation accuracy, and if the area is too small, it is difficult to divide the area due to the limited constraints of known well locations. For this reason, we propose a virtual well technology, that is, if the structural characteristics of two adjacent areas vary greatly and there are no known wells in the structural transition area, a virtual well can be set in the transition area, and each small area must contain 1 known well; after the structural area is divided, the area with a large number of known wells is calculated first, and then expanded outward to calculate the geostress distribution of the entire area.

[0090] Please refer to Figure 5. The present application also provides a deep coal seam ground stress calculation device, which includes a fitting module, a calculation module, a construction module and an analysis module; the fitting module is used to fit and generate a quadratic surface based on the structural feature data of a preset area around the target well location in the target block structural map; the calculation module is used to determine the physical parameters of the target layer through logging data and indoor experimental data, and calculate the horizontal ground stress component caused by vertical ground stress, the horizontal ground stress component caused by macroscopic structure, and the horizontal ground stress component caused by microscopic structure according to the physical parameters and the quadratic surface; the construction module is used to decompose the horizontal ground stress component caused by vertical ground stress and the horizontal ground stress component caused by macroscopic structure to the direction of the basic axis with the direction of the horizontal ground stress component caused by microscopic structure as the basic axis, and establish an analytical equation including a macroscopic structural stress coefficient and a microscopic structural stress coefficient; the analysis module is used to calculate the structural stress coefficient according to the analytical equation, and calculate the magnitude and direction of the horizontal ground stress of the target well location through the structural stress coefficient, rock mechanics parameters and formation pressure.

[0091] In actual work, the specific implementation process of each component is as follows:

[0092] Step 1: After the target well area is selected, the structural characteristic parameters near the target well location are extracted using the structural map, and the latitude, longitude and elevation data are extracted. At the same time, coordinate conversion is required to convert the geodetic coordinates into XYZ coordinates in the rectangular coordinate system to facilitate the subsequent surface fitting.

[0093] Step 2: Determine the static rock mechanics data of the target layer through well logging combined with laboratory experiments, including elastic modulus, Poisson's ratio, tensile strength, and effective stress coefficient; and determine the formation pressure of the target layer using injection / pressure drop test data.

[0094] Step 3: Calculate the vertical in-situ stress of the target layer using density logging data;

[0095] Step 4: Using the vertical in-situ stress, formation pressure, Poisson's ratio, and effective stress coefficient of the target layer, calculate the horizontal in-situ stress component caused by the vertical stress of the layer. The specific calculation formula is as follows:

[0096] in, are the maximum and minimum horizontal stress components caused by vertical stress, MPa; ν is Poisson's ratio, dimensionless; σ V is the vertical ground stress, MPa; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0097] Step 5: Using the vertical in-situ stress, formation pressure, and effective stress coefficient of the target layer, calculate the horizontal in-situ stress component caused by the macrostructure of the layer and obtain an equation containing the macrostructure coefficient. The specific calculation formula is as follows:

[0098] in, are the maximum and minimum horizontal stress components caused by macrostructure, MPa; β1 and β2 are macrostructure coefficients, dimensionless; α is the effective stress coefficient, dimensionless; P P is the formation pressure, MPa.

[0099] Step 6: Using the elastic modulus, Poisson's ratio, and structural data (curvature) of the target horizon, calculate the horizontal stress component caused by the microstructure of the horizon and obtain an equation containing the microstructure coefficient. The specific calculation formula is as follows:

[0100] in, are the ground stress components caused by microstructure, MPa; ν is Poisson's ratio, dimensionless; E is elastic modulus, MPa; β3 is macrostructure coefficient, dimensionless; a, b, c are the x values ​​in the fitted quadratic surface equation. 2 ,y 2 and the coefficients of the xy terms, dimensionless.

[0101] Step 7: Determine the direction of each stress component. The horizontal stress component caused by vertical stress is equal in all directions. The direction of horizontal stress caused by macrostructure is determined by averaging multipole array acoustic logging data from multiple wells in the target area. The direction of horizontal stress caused by microstructure is calculated using the two-dimensional stress components and shear stress.

[0102] Where θ is the angle between the microscopic maximum principal stress component and the x-axis; are the maximum and minimum horizontal stress components caused by microstructure, MPa; Maximum principal stress corresponding to the microstructure, MPa;

[0103] The final maximum principal stress direction can be obtained by the following formula of the resultant force and shear stress in the xy direction.

[0104] in, is the angle between the maximum principal stress direction and the x-axis; σ x ,σ y are the sum of the stress components in the x and y directions, τ xy is the shear stress in the xy plane, MPa;

[0105] Step 8: Taking the horizontal geostress direction caused by microstructure as the basic axis, decompose the horizontal geostress components in other directions into this direction, and establish an equation containing two macrostructure stress coefficients and one microstructure stress coefficient;

[0106] Refer to Figure 6. For Wells X1 and X2, corresponding component equations are established and solved. Since these two wells are located in the same wellbore, their corresponding tectonic stress coefficients β1, β2, and β3 can be assumed to be identical. After determining the horizontal in-situ stress components caused by vertical stress, macrostructure, and microstructure, the equations are combined to determine the least squares fitting solution.

[0107] Among them, σ x1 ,σ y1 , τ xy1 are the two normal stress components and the shear stress component, MPa; are the stress components caused by vertical stress, macrostructure, and local microstructure, MPa, respectively.

[0108] Step 9: Solve equation (8) to determine the three tectonic stress coefficients. Since the number of equations exceeds the number of unknowns, the solution obtained is the least squares fitting solution.

[0109] Step 10: After determining the three tectonic stress coefficients, substitute the coefficients back into the formula, compare the actual values ​​with the fitted values, and perform quantitative analysis. This method has a prediction error of less than 10%, demonstrating high reliability. The tectonic stress coefficients, rock mechanical parameters, and formation pressure are then used to calculate the magnitude and direction of horizontal geostress at other wells in the region (Well X3).

[0110] Step 11: (1) to (10) above are specific calculation methods for a single well. Another innovative point of this geostress calculation method is that it can calculate the geostress of the entire target area. First, based on the structural map, use geological software to read the curvature value;

[0111] Step 12: Divide the area into several small areas according to the curvature value (the curvature value is positive, negative and zero), and the micro-tectonic stress coefficient of each area is different. It should be pointed out that when partitioning, if the area is too large, it is easy to cause low calculation accuracy, and if the area is too small, it is difficult to divide the area due to the limited constraints of known well locations. For this reason, we propose a virtual well technology (X4 well), that is, if the structural characteristics of two adjacent areas vary greatly and there is no known well in the structural transition area, a virtual well can be set in the transition area. Each small area must contain 1 known well;

[0112] Step 13: After the structural area division is completed (see Figure 7 for the specific division), first calculate the area with a large number of known wells, and then expand outward to calculate the ground stress distribution of the entire area.

[0113] The beneficial technical effect of the present application is that the magnitude and direction of the ground stress of multiple wells can be calculated when the logging data is limited, and the prediction results are highly accurate.

[0114] The present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method when executing the computer program.

[0115] The present application also provides a computer-readable storage medium, which stores a computer program for executing the above method.

[0116] The present application also provides a computer program product, comprising a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0117] As shown in FIG8 , the electronic device 600 may further include: a communication module 110, an input unit 120, an audio processor 130, a display 160, and a power supply 170. It is worth noting that the electronic device 600 does not necessarily include all of the components shown in FIG8 ; in addition, the electronic device 600 may also include components not shown in FIG8 , for which reference may be made to the prior art.

[0118] As shown in FIG8 , the central processing unit 100 is sometimes also referred to as a controller or an operation control unit, and may include a microprocessor or other processor devices and / or logic devices. The central processing unit 100 receives inputs and controls the operations of various components of the electronic device 600 .

[0119] Memory 140 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store the aforementioned failure-related information and may also store programs that execute the relevant information. The CPU 100 may execute the programs stored in memory 140 to implement information storage or processing.

[0120] The input unit 120 provides input to the CPU 100. The input unit 120 may be, for example, a keypad or touch input device. The power supply 170 is used to provide power to the electronic device 600. The display 160 is used to display objects such as images and text. The display may be, for example, an LCD display, but is not limited thereto.

[0121] The memory 140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), or a SIM card. Alternatively, it may be a memory that retains information even when power is off, can be selectively erased, and is provided with more data. Examples of such memory are sometimes referred to as EPROMs. The memory 140 may also be some other type of device. The memory 140 includes a buffer memory 141 (sometimes referred to as a buffer). The memory 140 may include an application / function storage unit 142 for storing application programs and function programs or processes for executing the operations of the electronic device 600 via the central processing unit 100.

[0122] The memory 140 may also include a data storage unit (data 143) for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit (driver 144) of the memory 140 may include various driver programs for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0123] The communication module 110 is a transmitter / receiver 110 that transmits and receives signals via an antenna 111. The communication module (transmitter / receiver) 110 is coupled to the central processor 100 to provide input signals and receive output signals, which may be the same as in a conventional mobile communication terminal.

[0124] Based on different communication technologies, multiple communication modules 110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module, and / or a wireless local area network module. The communication module (transmitter / receiver) 110 is also coupled to a speaker 131 and a microphone 132 via an audio processor 130 to provide audio output via the speaker 131 and receive audio input from the microphone 132, thereby implementing common telecommunication functions. The audio processor 130 may include any suitable buffer, decoder, amplifier, etc. Furthermore, the audio processor 130 is also coupled to the central processing unit 100, enabling local recording via the microphone 132 and playback of stored audio via the speaker 131.

[0125] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0126] The present application is described with reference to the flow chart and / or block diagram of the method, device (system), and computer program product according to the embodiment of the present application. It should be understood that each flow process and / or box in the flow chart and / or block diagram and the combination of the flow process and / or box in the flow chart and / or block diagram can be realized by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processing machine or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for realizing the function specified in one flow chart flow or multiple flows and / or one box or multiple boxes of the block diagram.

[0127] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0129] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for calculating in-situ stress in deep coal seams, characterized in that, the method includes: fitting a quadratic surface according to the structural feature data of a preset area around a target well position in a target block structure map; determining the physical parameters of a target horizon through acquired well logging data and laboratory experiment data, and respectively calculating and obtaining the horizontal stress component caused by vertical in-situ stress, the horizontal stress component caused by macroscopic structures, and the horizontal stress component caused by microscopic structures according to the physical parameters and the quadratic surface; taking the direction of the horizontal stress component caused by microscopic structures as the base axis, decomposing the horizontal stress components of the horizontal stress component caused by vertical in-situ stress and the horizontal stress component caused by macroscopic structures to the base axis direction to establish an analytical equation including a macroscopic structure stress coefficient and a microscopic structure stress coefficient; calculating and obtaining the structure stress coefficient according to the analytical equation, and calculating the magnitude and direction of the horizontal in-situ stress of the target well position through the structure stress coefficient, rock mechanics parameters and formation pressure.

2. The method for calculating in-situ stress in deep coal seams according to claim 1, characterized in that, the structural feature data of a preset area around a target well position in a target block structure map further includes: extracting the longitude, latitude and elevation data of the structural feature parameters of a preset area around a target well position through a target block structure map; performing coordinate transformation on the longitude, latitude and elevation data into geodetic coordinate data, and converting the geodetic coordinate data into coordinate information in a rectangular coordinate system; fitting a quadratic surface through the coordinate information, and obtaining the coefficients of two quadratic terms and a cross term according to the quadratic surface.

3. The method for calculating in-situ stress in deep coal seams according to claim 2, characterized in that, the physical parameters include the static rock mechanics data of a target horizon, the formation pressure of a target horizon and the vertical in-situ stress of a target horizon; wherein, the static rock mechanics data of a target horizon is determined through well logging and laboratory experiments; the formation pressure of a target horizon is obtained according to injection pressure drawdown test data; the vertical in-situ stress of a target horizon is calculated by using density well logging data.

4. The method for calculating in-situ stress in deep coal seams according to claim 3, characterized in that, the static rock mechanics data includes elastic modulus, Poisson's ratio, tensile strength and effective stress coefficient.

5. The method for calculating in-situ stress in deep coal seams according to claim 4, characterized in that, respectively calculating and obtaining the horizontal stress component caused by vertical in-situ stress according to the physical parameters and the quadratic surface includes: calculating and obtaining the horizontal stress component caused by vertical in-situ stress through the vertical in-situ stress of a target horizon, the formation pressure and the corresponding Poisson's ratio and effective stress coefficient.

6. The method for calculating in-situ stress in deep coal seams according to claim 3, characterized in that, respectively calculating and obtaining the horizontal stress component caused by macroscopic structures according to the physical parameters and the quadratic surface includes: constructing a macroscopic equation containing a macroscopic structure coefficient through the vertical in-situ stress of a target horizon, the formation pressure and the corresponding effective stress coefficient; calculating and obtaining the horizontal stress component caused by macroscopic structures according to the macroscopic equation.

7. The method for calculating ground stress in deep coal seams according to claim 4, It is characterized in that The horizontal ground stress components caused by the microstructure are calculated and obtained according to the physical parameters and the quadratic surface, respectively, including: Constructing a microscopic equation containing microscopic structural coefficients using the elastic modulus, Poisson's ratio, and coefficients of the quadratic term and the cross term of the target layer; The horizontal ground stress component caused by the microstructure is obtained by calculating the micro equation.

8. The method for calculating ground stress in deep coal seams according to claim 1, It is characterized in that Taking the direction of the horizontal stress component caused by microstructure as the basic axis, it also includes: Determine the direction of horizontal geostress caused by macrostructures by averaging multiple wells in the target area; Determine the direction of horizontal ground stress caused by microstructures through calculation of structural and rock mechanics data; The actual ground stress direction is determined using multipole array acoustic logging data.

9. The method for calculating ground stress in deep coal seams according to claim 1, It is characterized in that Decomposing the horizontal geostress component caused by the vertical geostress and the horizontal geostress component caused by the macro structure to the direction of the foundation axis, an analytical equation including a macro structure stress coefficient and a micro structure stress coefficient is established, comprising: Based on the fact that the horizontal geostress system caused by vertical geostress, the horizontal geostress system caused by macroscopic structure, and the horizontal geostress system caused by microscopic structure are the same, the horizontal geostress component caused by vertical geostress, the horizontal geostress component caused by macroscopic structure, and the horizontal geostress component caused by microscopic structure are jointly established to establish an analytical equation including a macroscopic structural stress coefficient and a microscopic structural stress coefficient.

10. The method for calculating ground stress in deep coal seams according to claim 1, It is characterized in that Calculating the tectonic stress coefficient according to the analytical equation includes: solving the analytical equation by least squares fitting to obtain the tectonic stress coefficient.

11. A regional geostress calculation method comprising the deep coal seam geostress calculation method according to any one of claims 1 to 10, It is characterized in that The method comprises: Obtaining a curvature value according to a target block construction diagram, and dividing the target block into a plurality of regions according to the curvature value; Calculate the magnitude and direction of horizontal in-situ stress at each well location in the area by using the deep coal seam in-situ stress calculation method to obtain corresponding in-situ stress information; The geostress distribution data of the target block is obtained according to the geostress information.

12. The method for calculating regional geostress according to claim 11, It is characterized in that Dividing the target block into a plurality of regions according to the curvature value further comprises: When the difference between the structural characteristic data of two adjacent areas is greater than a preset threshold, and there is no known well in the transition area between the two areas, a virtual well is constructed in the transition area.

13. A deep coal seam ground stress calculation device, It is characterized in that The device comprises a fitting module, a calculation module, a construction module and an analysis module; The fitting module is used to fit and generate a quadratic surface based on the structural feature data of a preset area around the target well position in the target block structural map; The calculation module is used to determine the physical parameters of the target horizon through logging data and laboratory experiment data, and calculate the horizontal stress component caused by vertical stress, the horizontal stress component caused by macroscopic structure, and the horizontal stress component caused by microscopic structure respectively according to the physical parameters and the quadratic surface; The construction module is used to take the direction of the horizontal stress component caused by microscopic structure as the base axis, decompose the horizontal stress components of the horizontal stress component caused by vertical stress and the horizontal stress component caused by macroscopic structure into the base axis direction, and establish an analytical equation including a macroscopic structure stress coefficient and a microscopic structure stress coefficient; The analysis module is used to calculate the structural stress coefficient according to the analytical equation, and calculate the magnitude and direction of the horizontal stress at the target well position through the structural stress coefficient, rock mechanics parameters and formation pressure.

14. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, when the processor executes the computer program, the method according to any one of claims 1 to 12 is implemented.

15. A computer-readable storage medium, wherein, the computer-readable storage medium stores a computer program for the computer to execute the method according to any one of claims 1 to 12.

16. A computer program product, comprising a computer program / instructions, wherein, when the computer program / instructions are executed by the processor, the steps of the method according to any one of claims 1 to 12 are implemented.

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