Method, device and medium for determining horizontal principal stress of anisotropic rock

Abstract

The application discloses a method, device, equipment and medium for determining anisotropic rock horizontal principal stress. The method comprises the following steps: obtaining the volume density of a core and the velocity information of at least one coring sample; determining a rigidity coefficient according to the volume density of the core and the velocity information of the at least one coring sample; and determining the anisotropic rock horizontal principal stress according to the rigidity coefficient, the pre-calculated overburden pressure and the strain information measured based on the differential strain experiment. The method solves the limitation problem of the differential strain method, can more accurately evaluate the horizontal principal stress, and is beneficial to providing effective parameters for oil and gas enrichment distribution, hydraulic fracturing, wellbore stability analysis and the like.

Description

Technical Field

[0001] This invention relates to the field of geophysical technology, and in particular to a method, apparatus, equipment and medium for determining the horizontal principal stress of anisotropic rocks. Background Technology

[0002] The migration and accumulation of oil and gas during oil and gas exploration and development, wellbore stability during drilling, horizontal well design, reservoir stimulation, and well network layout during water injection development are all closely related to horizontal principal stress. Effectively and accurately evaluating the horizontal principal stress of reservoirs is of great significance for oil and gas exploration and development.

[0003] Currently, determining the horizontal principal stress based on differential strain experiments is a common indoor geostress measurement method. The theoretical basis of the differential strain method is reliable, and it has achieved good results in many geostress measurement projects. However, the differential strain method assumes isotropic conditions. In practical application scenarios, such as shale oil and gas reservoirs, rocks are usually anisotropic. Changes in physical properties lead to inaccurate horizontal principal stress values ​​measured by conventional differential strain experiments. Summary of the Invention

[0004] This invention provides a method, apparatus, equipment, and medium for determining the horizontal principal stress of anisotropic rocks, which solves the limitations of the differential strain method and can more accurately evaluate the horizontal principal stress, thus providing effective parameters for oil and gas enrichment distribution, hydraulic fracturing, wellbore stability analysis, etc.

[0005] According to one aspect of the present invention, a method for determining the horizontal principal stress of anisotropic rocks is provided, the method comprising:

[0006] Obtain core bulk density and velocity information of at least one core sample;

[0007] The stiffness coefficient is determined based on the core bulk density and the velocity information of at least one core sample.

[0008] Based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments, the horizontal principal stress of the anisotropic rock is determined.

[0009] According to another aspect of the present invention, an apparatus for determining the horizontal principal stress of anisotropic rocks is provided, the apparatus comprising:

[0010] The information acquisition module is used to acquire the core volume density and the velocity information of at least one core sample;

[0011] The stiffness coefficient determination module is used to determine the stiffness coefficient based on the core bulk density and the velocity information of at least one core sample.

[0012] The horizontal principal stress determination module is used to determine the horizontal principal stress of anisotropic rocks based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments.

[0013] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0014] At least one processor; and

[0015] A memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the method for determining the horizontal principal stress of anisotropic rocks according to any embodiment of the present invention.

[0017] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the method for determining the horizontal principal stress of anisotropic rocks according to any embodiment of the present invention.

[0018] The technical solution of this invention obtains the core bulk density and velocity information of at least one core sample. Based on the core bulk density and velocity information of at least one core sample, a stiffness coefficient is determined. Then, based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments, the horizontal principal stress of anisotropic rocks is determined. This solution overcomes the limitations of the differential strain method, enabling a more accurate evaluation of the horizontal principal stress, and is beneficial for providing effective parameters for oil and gas enrichment distribution, hydraulic fracturing, and wellbore stability analysis.

[0019] It should be understood that the description in this section is not intended to identify key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1A This is a flowchart of a method for determining the horizontal principal stress of anisotropic rocks according to Embodiment 1 of the present invention;

[0022] Figure 1B This is a schematic diagram of core sample drilling according to an embodiment of the present invention;

[0023] Figure 1C This is a schematic diagram of sound wave velocity measurement according to an embodiment of the present invention;

[0024] Figure 1D This is a schematic diagram of determining the orientation of the horizontal principal stress according to an embodiment of the present invention;

[0025] Figure 1E This is a stress-strain variation curve provided according to an embodiment of the present invention;

[0026] Figure 2 This is a flowchart of a method for determining the horizontal principal stress of anisotropic rocks according to Embodiment 2 of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of an anisotropic rock horizontal principal stress determination device provided in Embodiment 3 of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of an electronic device for implementing the method for determining the horizontal principal stress of anisotropic rocks provided in the embodiments of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate to allow for implementation beyond what is illustrated or described in the embodiments of the invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] Example 1

[0032] Figure 1AThis is a flowchart of a method for determining the horizontal principal stress of anisotropic rocks according to Embodiment 1 of the present invention. This embodiment is applicable to the scenario of measuring the horizontal principal stress of anisotropic rocks. The method can be executed by an anisotropic rock horizontal principal stress determination device, which can be implemented in hardware and / or software and can be configured in an electronic device. Figure 1A As shown, the method includes:

[0033] S110. Obtain the core volume density and velocity information of at least one core sample.

[0034] This solution can be executed by electronic devices such as computers. The electronic devices can read the core volume density obtained by measuring the mass and volume of core samples taken during drilling. The core volume density can be obtained based on measurements of one or more core samples; for example, the electronic devices can use the average volume density of multiple core samples as the core volume density. Wave velocity measurement equipment can measure the wave velocity of the core samples to obtain velocity information. This velocity information can include shear wave velocity and longitudinal wave velocity in at least three directions. Figure 1B This is a schematic diagram of core sampling according to an embodiment of the present invention. The core sampling process can also involve sampling the rock core from at least three directions to obtain at least three core samples, such as... Figure 1B Using the bedding plane as a reference, core samples were drilled in three directions: horizontal, vertical, and at a 45° angle to the axis of symmetry, yielding three core samples. Wave velocity measurements were then performed on each core sample using a wave velocity measurement device.

[0035] Figure 1C This is a schematic diagram of sound wave velocity measurement according to an embodiment of the present invention. Figure 1C As shown, wave velocity measurement equipment can measure wave velocity separately for different cored samples, obtaining the longitudinal wave velocity and transverse wave velocity in different directions. It is easy to understand that a longitudinal wave can be a wave in which the direction of particle motion is parallel to the wave propagation direction, and a transverse wave can be a wave in which the direction of particle motion is perpendicular to the wave propagation direction. The longitudinal wave velocity can be the speed at which the longitudinal wave propagates in the cored sample, and the transverse wave velocity can be the speed at which the transverse wave propagates in the cored sample.

[0036] S120. Determine the stiffness coefficient based on the core bulk density and the velocity information of at least one core sample.

[0037] Based on the core bulk density and velocity information in at least three directions from at least one core sample, an electronic device can calculate a stiffness coefficient matrix. This stiffness coefficient matrix can be a combination of stiffness coefficients in each direction, typically a 6-dimensional matrix. Stiffness coefficients, also known as elastic coefficients, are used to describe the stress-strain relationship of an elastic body. The stress-strain relationship can be expressed as: τ ij =C ijkl ·ε kl ; where τ ij ε represents stress. kl Indicates strain, C ijkl This represents the stiffness coefficients. The stiffness coefficient matrix can be a symmetric matrix, meaning it has all elements equal around its main diagonal. A 6-dimensional stiffness coefficient matrix can be represented as:

[0038]

[0039] It is understandable that the physical properties of an elastomer can be measured in different directions. If the measurement results are the same in all directions, it indicates that the physical properties of the elastomer are independent of orientation, i.e., isotropic. If the physical properties of the elastomer are closely related to orientation, and the measurement results differ significantly in different orientations, i.e., anisotropic, the intrinsic factor causing this difference is the asymmetry of the elastomer material structure. Dense rocks are generally considered to be transversely isotropic elastomers. Transversely isotropic bodies are a special case of anisotropic bodies. Transversely isotropic elastomers exhibit consistent elastic properties in all directions within the layered plane, but different elastic properties in directions perpendicular to the layered plane.

[0040] Taking a 6-dimensional stiffness coefficient matrix as an example, for a transversely isotropic medium, due to its symmetry on the layered plane, the relationship between the stiffness coefficients is as follows: C 11 =C 22 C 13 =C 23 C 44 =C 55 C 14 =C 15 =C 16 =0, C 24 =C 25 =C 26 =0, C 34 =C 35 =C 36 =0, C 45 =C 46 =C 56 =0, where C 12 =C 11 -2C 66 Therefore, only C needs to be calculated. 11 C 13 C33 C 44 and C 66 It can characterize the elastic properties of transversely isotropic media.

[0041] Based on velocity information from at least one core sample, the electronic device can calculate the P-wave velocities in three directions associated with the bedding direction and the S-wave velocities in two directions associated with the bedding direction. Furthermore, it can calculate the aforementioned stiffness coefficient based on the core bulk density, S-wave velocity, and P-wave velocity. The P-wave velocities in the three directions can be perpendicular to the bedding direction, parallel to the bedding direction, and at a 45° angle to the bedding direction. The S-wave velocities in the two directions can be perpendicular to the bedding direction and parallel to the bedding direction.

[0042] It's easy to understand, C 11 It can be calculated based on the core bulk density and the P-wave velocity parallel to the bedding direction. C 33 It can be calculated based on the core bulk density and the P-wave velocity perpendicular to the bedding direction. C 44 It can be determined based on the core bulk density and the transverse wave velocity perpendicular to the bedding direction. C 66 It can be determined based on the core bulk density and the transverse wave velocity parallel to the bedding direction. According to C... 11 and C 66 Electronic devices can calculate C 12 Based on the rock's bulk density, C 11 C 33 C 44 And the longitudinal wave velocity at a 45° angle to the bedding direction, electronic equipment can determine C 13 .

[0043] S130. Based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments, determine the horizontal principal stress of the anisotropic rock.

[0044] Figure 1D This is a schematic diagram illustrating the determination of the horizontal principal stress orientation according to an embodiment of the present invention. In this scheme, the orientations of the maximum and minimum horizontal principal stresses can be determined based on the magnitude of the ultrasonic velocity in different orientations. Since stress release after the core is extracted from the formation causes micro-fractures to form inside the core, these fractures expand along the direction of the maximum horizontal principal stress, resulting in the minimum ultrasonic velocity in the direction of the maximum horizontal principal stress and the maximum ultrasonic velocity in the direction of the minimum horizontal principal stress. The ultrasonic velocities in other directions fall between these two. In actual measurement, a temporary, erasable marker line is first marked on the core sample as the 0° angle for testing the wave velocity anisotropy. The ultrasonic velocity is measured every 15°, for one complete cycle. Figure 1DAs shown, sine or cosine curves are fitted to the measured ultrasonic velocity data. The angle of maximum ultrasonic velocity is the direction of minimum horizontal principal stress, and the angle of minimum ultrasonic velocity is the direction of maximum horizontal principal stress, thus determining the relative orientation of the horizontal principal stress. Based on... Figure 1D The curves shown indicate that the angle corresponding to the maximum velocity is the orientation of the minimum horizontal principal stress, which is approximately 48°, and the angle corresponding to the minimum velocity is the orientation of the maximum horizontal principal stress, which is approximately 132°.

[0045] After determining the orientations of the maximum and minimum horizontal principal stresses, stress and strain data can be measured by applying pressure to the cored sample using differential strain testing. Specifically, the applied pressure is typically greater than 20 MPa to ensure complete closure of microcracks. The stress and strain data are the recorded changes in strain as stress increases during the experiment. Figure 1E This is a stress-strain variation curve provided according to an embodiment of the present invention. Figure 1E The long dashed line represents the vertical strain variation with pressure, the short dashed line represents the maximum horizontal principal strain variation with pressure, the dotted line represents the minimum horizontal principal strain variation with pressure, and the solid line is a vertical line drawn from the determined overburden pressure value. The strain values ​​at the intersections of the vertical strain, the maximum horizontal principal strain, and the minimum horizontal principal strain are ε1, ε2, and ε3, respectively.

[0046] To determine the maximum and minimum horizontal principal stresses, the overburden pressure must first be determined. Then, the principal strains corresponding to the overburden pressure, maximum horizontal principal stress, and minimum horizontal principal stress must be determined. Finally, the maximum and minimum horizontal principal stresses are determined based on the relationship between pressure, stiffness coefficient, and principal strain. The overburden pressure can be calculated based on the integration of density over depth. Specifically, the formula for calculating the overburden pressure can be expressed as: Where z represents depth, ρ(z) represents density as a function of depth, and g represents gravitational acceleration.

[0047] Understandably, the ratios of overburden pressure, maximum horizontal principal stress, and minimum horizontal principal stress have the following relationship: S1:S2:S3=(α 11 ε1+α 12 ε2+α 13 ε3):(α 12 ε1+α 22 ε2+α 23 ε3):(α 13 ε1+α 23 ε2+α 33 ε3); where S2 represents the maximum horizontal principal stress, S3 represents the minimum horizontal principal stress, ε1 represents the strain corresponding to the overburden pressure, ε2 represents the strain corresponding to the maximum horizontal principal stress, and ε3 represents the strain corresponding to the minimum horizontal principal stress. α 11 α12 α 13 α 22 α 23 and α 33 The parameters representing the stress-strain relationship can be calculated based on the stiffness coefficient.

[0048] This technical solution obtains the core bulk density and velocity information from at least one core sample. Based on these parameters, a stiffness coefficient is determined. Then, using the stiffness coefficient, pre-calculated overburden pressure, and strain information obtained from differential strain experiments, the horizontal principal stress of anisotropic rocks is determined. This solution overcomes the limitations of the differential strain method, enabling more accurate evaluation of the horizontal principal stress and providing effective parameters for oil and gas enrichment distribution, hydraulic fracturing, and wellbore stability analysis.

[0049] Example 2

[0050] Figure 2 This is a flowchart of a method for determining the horizontal principal stress of anisotropic rocks according to Embodiment 2 of the present invention. This embodiment is an optimization based on the above embodiment. Figure 2 As shown, the method includes:

[0051] S210. Obtain the core volume density and velocity information of at least one core sample.

[0052] S220. Based on the velocity information of at least one cored sample, determine the longitudinal wave velocity in three directions associated with the bedding direction and the transverse wave velocity in two directions associated with the bedding direction.

[0053] In this scheme, determining the P-wave velocities in three directions associated with the bedding direction and the S-wave velocities in two directions associated with the bedding direction based on the velocity information of at least one cored sample includes:

[0054] Based on the velocity information from at least one cored sample, determine the P-wave velocity perpendicular to the bedding direction, the P-wave velocity parallel to the bedding direction, the S-wave velocity perpendicular to the bedding direction, the S-wave velocity parallel to the bedding direction, and the P-wave velocity at a 45° angle to the bedding direction.

[0055] It's easy to understand that shear wave velocities are divided into two velocities, propagating in the same direction but with perpendicular polarization directions. One polarization direction is parallel to the bedding plane, called a fast shear wave; the other polarization direction is perpendicular to the bedding plane, called a slow shear wave. Figure 1C For example, V S190 For the velocity of a slow transverse wave, V S290 The speed of the fast transverse wave.

[0056] S230. Calculate the stiffness coefficient based on the core bulk density, the longitudinal wave velocity in three directions associated with the bedding direction, and the transverse wave velocity in two directions associated with the bedding direction.

[0057] In one feasible approach, calculating the stiffness coefficient based on the core bulk density, the P-wave velocities in three directions associated with the bedding direction, and the S-wave velocities in two directions associated with the bedding direction includes:

[0058] The first stiffness coefficient is calculated based on the core bulk density and the longitudinal wave velocity parallel to the bedding direction.

[0059] The second stiffness coefficient is calculated based on the core bulk density and the longitudinal wave velocity perpendicular to the bedding direction;

[0060] The third stiffness coefficient is calculated based on the core bulk density and the transverse wave velocity perpendicular to the bedding direction.

[0061] The fourth stiffness coefficient is calculated based on the core bulk density and the transverse wave velocity parallel to the bedding direction.

[0062] Calculate the fifth rigidity coefficient based on the first rigidity coefficient and the fourth rigidity coefficient;

[0063] The sixth rigidity coefficient is calculated based on the core bulk density, the first rigidity coefficient, the second rigidity coefficient, the third rigidity coefficient, and the longitudinal wave velocity at a 45° angle to the bedding direction.

[0064] Specifically, the stiffness coefficient is an element in the stiffness coefficient matrix, denoted as C. ij ,i represents the row of the element, and j represents the column of the element. The Christoffel equation is a form of the wave equation, suitable for describing wave propagation in anisotropic media. For the transversely isotropic strata described in this invention, the Christoffel equation can be expressed as:

[0065]

[0066] The elements of the Christoffel matrix are:

[0067]

[0068] in:

[0069]

[0070] In the formula, ω represents the angular frequency, k represents the wavenumber, ρ represents the core bulk density, and x, y, and z represent different propagation directions, where the x, y, and z directions are mutually perpendicular; kx k y and k z Let l represent the wavenumber components in the x, y, and z propagation directions. x l y and l z Let υ represent the wavenumber cosines in the x, y, and z propagation directions, respectively. x υ y and υ z These represent the velocity components in the x, y, and z propagation directions, respectively.

[0071] By solving the Christoffel equation, the formula for calculating the stiffness coefficient can be obtained:

[0072] The formula for calculating the first stiffness coefficient is:

[0073] The formula for calculating the second stiffness coefficient is:

[0074] The formula for calculating the third stiffness coefficient is as follows:

[0075] The formula for calculating the fourth stiffness coefficient is as follows:

[0076] The formula for calculating the fifth stiffness coefficient is: C 12 =C 11 -2C 66 ;

[0077] The formula for calculating the sixth stiffness coefficient is as follows:

[0078] Where ρ represents the core bulk density, V P90 V represents the longitudinal wave velocity parallel to the bedding direction. P0 V represents the longitudinal wave velocity perpendicular to the bedding direction. S190 V represents the transverse wave velocity perpendicular to the bedding direction. S290 V represents the transverse wave velocity parallel to the bedding direction. P45 This indicates the longitudinal wave velocity at a 45° angle to the bedding direction.

[0079] S240. Based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments, determine the horizontal principal stress of the anisotropic rock.

[0080] In this scheme, optionally, determining the horizontal principal stress of the anisotropic rock based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments includes:

[0081] Based on the first stiffness coefficient, the second stiffness coefficient, the fifth stiffness coefficient, and the sixth stiffness coefficient, a first parameter group and a second parameter group are determined; wherein, the first parameter group is associated with the maximum horizontal principal stress; and the second parameter group is associated with the minimum horizontal principal stress.

[0082] Based on the first parameter set, the second parameter set, the overburden pressure, and the strain information, the maximum horizontal principal stress and the minimum horizontal principal stress are determined; wherein, the strain information includes the strain matched by the overburden pressure, the strain matched by the maximum horizontal principal stress, and the strain matched by the minimum horizontal principal stress.

[0083] Specifically, the first parameter group includes α 11 α 12 α 13 α 22 and α 23 The second parameter set includes α 11 α 12 α 13 α 23 and α 33 ; where α 11 α 12 α 13 α 22 α 23 and α 33 The calculation formulas are as follows:

[0084]

[0085]

[0086]

[0087]

[0088] The formula for calculating the maximum horizontal principal stress is expressed as:

[0089] The formula for calculating the minimum horizontal principal stress is expressed as follows:

[0090] Where S1 represents the overburden pressure, ε1 represents the strain matched by the overburden pressure, ε2 represents the strain matched by the maximum horizontal principal stress, and ε3 represents the strain matched by the minimum horizontal principal stress.

[0091] In a specific example, the core bulk density, P-wave velocity perpendicular to the bedding direction, P-wave velocity parallel to the bedding direction, S-wave velocity perpendicular to the bedding direction, S-wave velocity parallel to the bedding direction, and P-wave velocity at a 45° angle to the bedding direction are shown in Table 1 below.

[0092] Table 1:

[0093] 2.49 5220 4967 4832 3003 3020

[0094] Based on the core bulk density, P-wave velocity perpendicular to the bedding direction, P-wave velocity parallel to the bedding direction, S-wave velocity perpendicular to the bedding direction, S-wave velocity parallel to the bedding direction, and P-wave velocity at a 45° angle to the bedding direction in Table 1, the electronic equipment calculates the stiffness coefficient C according to the formula in S230. 11 C 12 C 13 C 33 C 44 and C 66 The values ​​of are shown in Table 2 below.

[0095] Table 2:

[0096] 67.84 58.54 22.45 22.71 16.01 10.81

[0097] Based on the rigidity coefficient values ​​in Table 2, the electronic device can calculate the parameters in each parameter group according to the calculation formula of the parameter group in S240, as shown in Table 3 below.

[0098] Table 3:

[0099] 0.016 -0.002 -0.003 0.018

[0100] Based on differential strain experiments, the electronic device can obtain the target's vertical strain ε1, maximum horizontal principal strain ε2, and minimum horizontal principal strain ε3. By integrating density over depth, the electronic device can calculate the overburden pressure S1. Based on ε1, ε2, ε3, S1, and the stress-strain relationship, the electronic device can calculate S2 and S3 using the formulas for calculating the maximum and minimum horizontal principal stresses. The calculation results for ε1, ε2, ε3, S1, S2, and S3 are shown in Table 4 below.

[0101] Table 4:

[0102]

[0103]

[0104] The minimum horizontal principal stress calculated according to this scheme is 30.2 MPa, and the minimum horizontal principal stress obtained by testing is 30.6 MPa. The relative error between the two is 1.31%. This scheme can greatly improve the accuracy of experimental measurement and data processing.

[0105] This technical solution obtains the core bulk density and velocity information from at least one core sample. Based on these parameters, a stiffness coefficient is determined. Then, using the stiffness coefficient, pre-calculated overburden pressure, and strain information obtained from differential strain experiments, the horizontal principal stress of anisotropic rocks is determined. This solution overcomes the limitations of the differential strain method, enabling more accurate evaluation of the horizontal principal stress and providing effective parameters for oil and gas enrichment distribution, hydraulic fracturing, and wellbore stability analysis.

[0106] Example 3

[0107] Figure 3 This is a schematic diagram of a device for determining the horizontal principal stress of anisotropic rocks according to Embodiment 3 of the present invention. Figure 3 As shown, the device includes:

[0108] Information acquisition module 310 is used to acquire core volume density and velocity information of at least one core sample;

[0109] The stiffness coefficient determination module 320 is used to determine the stiffness coefficient based on the core bulk density and the velocity information of at least one core sample.

[0110] The horizontal principal stress determination module 330 is used to determine the horizontal principal stress of anisotropic rocks based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments.

[0111] In this solution, optionally, the stiffness coefficient determination module 320 includes:

[0112] A velocity determination unit is used to determine the longitudinal wave velocity in three directions associated with the layering direction and the transverse wave velocity in two directions associated with the layering direction based on the velocity information of at least one cored sample.

[0113] The stiffness coefficient calculation unit is used to calculate the stiffness coefficient based on the core bulk density, the longitudinal wave velocity in three directions associated with the bedding direction, and the transverse wave velocity in two directions associated with the bedding direction.

[0114] Based on the above scheme, the speed determination unit is specifically used for:

[0115] Based on the velocity information from at least one cored sample, determine the P-wave velocity perpendicular to the bedding direction, the P-wave velocity parallel to the bedding direction, the S-wave velocity perpendicular to the bedding direction, the S-wave velocity parallel to the bedding direction, and the P-wave velocity at a 45° angle to the bedding direction.

[0116] Optionally, the stiffness coefficient calculation unit includes:

[0117] The first stiffness coefficient calculation subunit is used to calculate the first stiffness coefficient based on the core bulk density and the longitudinal wave velocity parallel to the bedding direction.

[0118] The second stiffness coefficient calculation subunit is used to calculate the second stiffness coefficient based on the core bulk density and the longitudinal wave velocity perpendicular to the bedding direction.

[0119] The third stiffness coefficient calculation subunit is used to calculate the third stiffness coefficient based on the core bulk density and the transverse wave velocity perpendicular to the bedding direction.

[0120] The fourth stiffness coefficient calculation subunit is used to calculate the fourth stiffness coefficient based on the core bulk density and the transverse wave velocity parallel to the bedding direction.

[0121] The fifth rigidity coefficient calculation subunit is used to calculate the fifth rigidity coefficient based on the first rigidity coefficient and the fourth rigidity coefficient;

[0122] The sixth rigidity coefficient calculation subunit is used to calculate the sixth rigidity coefficient based on the core bulk density, the first rigidity coefficient, the second rigidity coefficient, the third rigidity coefficient, and the longitudinal wave velocity at a 45° angle to the bedding direction.

[0123] In a preferred embodiment, the stiffness coefficient is an element in the stiffness coefficient matrix, denoted as C. ij ,i represents the row where the element is located, and j represents the column where the element is located;

[0124] The formula for calculating the first stiffness coefficient is:

[0125] The formula for calculating the second stiffness coefficient is:

[0126] The formula for calculating the third stiffness coefficient is as follows:

[0127] The formula for calculating the fourth stiffness coefficient is as follows:

[0128] The formula for calculating the fifth stiffness coefficient is: C 12 =C 11 -2C 66 ;

[0129] The formula for calculating the sixth stiffness coefficient is as follows:

[0130] Where ρ represents the core bulk density, V P90 V represents the longitudinal wave velocity parallel to the bedding direction. P0V represents the longitudinal wave velocity perpendicular to the bedding direction. S190 V represents the transverse wave velocity perpendicular to the bedding direction. S290 V represents the transverse wave velocity parallel to the bedding direction. P45 This indicates the longitudinal wave velocity at a 45° angle to the bedding direction.

[0131] Based on the above scheme, the horizontal principal stress determination module 330 includes:

[0132] The parameter group determination unit is used to determine a first parameter group and a second parameter group based on a first stiffness coefficient, a second stiffness coefficient, a fifth stiffness coefficient, and a sixth stiffness coefficient; wherein, the first parameter group is associated with the maximum horizontal principal stress; and the second parameter group is associated with the minimum horizontal principal stress.

[0133] The horizontal principal stress determination unit is used to determine the maximum and minimum horizontal principal stresses based on the first parameter set, the second parameter set, the overburden pressure, and strain information; wherein the strain information includes the strain matched by the overburden pressure, the strain matched by the maximum horizontal principal stress, and the strain matched by the minimum horizontal principal stress.

[0134] In one feasible approach, the first parameter set includes α 11 α 12 α 13 α 22 and α 23 The second parameter set includes α 11 α 12 α 13 α 23 and α 33 ; where α 11 α 12 α 13 α 22 α 23 and α 33 The calculation formulas are as follows:

[0135]

[0136]

[0137]

[0138]

[0139] The formula for calculating the maximum horizontal principal stress is expressed as:

[0140] The formula for calculating the minimum horizontal principal stress is expressed as follows:

[0141] Where S1 represents the overburden pressure, ε1 represents the strain matched by the overburden pressure, ε2 represents the strain matched by the maximum horizontal principal stress, and ε3 represents the strain matched by the minimum horizontal principal stress.

[0142] The anisotropic rock horizontal principal stress determination device provided in the embodiments of the present invention can execute the anisotropic rock horizontal principal stress determination method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method.

[0143] Example 4

[0144] Figure 4 A schematic diagram of the structure of an electronic device 410 that can be used to implement embodiments of the present invention is provided. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0145] like Figure 4 As shown, the electronic device 410 includes at least one processor 411 and a memory, such as a read-only memory (ROM) 412 or a random access memory (RAM) 413, communicatively connected to the at least one processor 411. The memory stores computer programs executable by the at least one processor. The processor 411 can perform various appropriate actions and processes based on the computer program stored in the ROM 412 or loaded from storage unit 418 into the RAM 413. The RAM 413 may also store various programs and data required for the operation of the electronic device 410. The processor 411, ROM 412, and RAM 413 are interconnected via a bus 414. An input / output (I / O) interface 415 is also connected to the bus 414.

[0146] Multiple components in electronic device 410 are connected to I / O interface 415, including: input unit 416, such as keyboard, mouse, etc.; output unit 417, such as various types of displays, speakers, etc.; storage unit 418, such as disk, optical disk, etc.; and communication unit 419, such as network card, modem, wireless transceiver, etc. Communication unit 419 allows electronic device 410 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0147] Processor 411 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 411 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 411 performs the various methods and processes described above, such as the method for determining the horizontal principal stress of anisotropic rocks.

[0148] In some embodiments, the method for determining the horizontal principal stress of anisotropic rocks may be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 418. In some embodiments, part or all of the computer program may be loaded and / or installed on electronic device 410 via ROM 412 and / or communication unit 419. When the computer program is loaded into RAM 413 and executed by processor 411, one or more steps of the method for determining the horizontal principal stress of anisotropic rocks described above may be performed. Alternatively, in other embodiments, processor 411 may be configured to perform the method for determining the horizontal principal stress of anisotropic rocks by any other suitable means (e.g., by means of firmware).

[0149] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0150] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0151] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0152] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0153] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0154] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0155] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0156] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for determining the horizontal principal stress in anisotropic rocks, characterized in that, include: Obtain core bulk density and velocity information of at least one core sample; Based on the velocity information of at least one core sample, determine the P-wave velocity perpendicular to the bedding direction, the P-wave velocity parallel to the bedding direction, the S-wave velocity perpendicular to the bedding direction, the S-wave velocity parallel to the bedding direction, and the P-wave velocity at a 45° angle to the bedding direction. The first stiffness coefficient is calculated based on the core bulk density and the longitudinal wave velocity parallel to the bedding direction. The second stiffness coefficient is calculated based on the core bulk density and the longitudinal wave velocity perpendicular to the bedding direction; The third stiffness coefficient is calculated based on the core bulk density and the transverse wave velocity perpendicular to the bedding direction. The fourth stiffness coefficient is calculated based on the core bulk density and the transverse wave velocity parallel to the bedding direction. Calculate the fifth rigidity coefficient based on the first rigidity coefficient and the fourth rigidity coefficient; The sixth rigidity coefficient is calculated based on the core bulk density, the first rigidity coefficient, the second rigidity coefficient, the third rigidity coefficient, and the longitudinal wave velocity at a 45° angle to the bedding direction. The stiffness coefficient is an element in the stiffness coefficient matrix, represented as follows: , Indicates the row where the element is located. Indicates the column where the element is located; The formula for calculating the first stiffness coefficient is: ; The formula for calculating the second stiffness coefficient is: ; The formula for calculating the third stiffness coefficient is as follows: ; The formula for calculating the fourth stiffness coefficient is as follows: ; The formula for calculating the fifth stiffness coefficient is as follows: ; The formula for calculating the sixth stiffness coefficient is as follows: ; in, Indicates the bulk density of the rock core. This represents the longitudinal wave velocity parallel to the bedding direction. This represents the longitudinal wave velocity perpendicular to the bedding direction. This represents the transverse wave velocity perpendicular to the bedding direction. This represents the transverse wave velocity parallel to the bedding direction. This indicates the longitudinal wave velocity at a 45° angle to the bedding direction; Based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments, the horizontal principal stresses of the anisotropic rock are determined, including: Based on the first stiffness coefficient, the second stiffness coefficient, the fifth stiffness coefficient, and the sixth stiffness coefficient, a first parameter group and a second parameter group are determined; wherein, the first parameter group is associated with the maximum horizontal principal stress; and the second parameter group is associated with the minimum horizontal principal stress. Based on the first parameter set, the second parameter set, the overburden pressure, and the strain information, the maximum horizontal principal stress and the minimum horizontal principal stress are determined; wherein, the strain information includes the strain matched by the overburden pressure, the strain matched by the maximum horizontal principal stress, and the strain matched by the minimum horizontal principal stress. The first parameter group includes , , , and The second parameter group includes , , , and ;in, , , , , and The calculation formulas are as follows: ； ； ； ； The formula for calculating the maximum horizontal principal stress is expressed as: ; The formula for calculating the minimum horizontal principal stress is expressed as follows: ; in, Indicates overlying pressure. This indicates the strain matched by the overlying pressure. This represents the strain at which the maximum horizontal principal stress is matched. This represents the strain at minimum horizontal principal stress matching.

2. A device for determining the horizontal principal stress of anisotropic rocks, characterized in that, include: The information acquisition module is used to acquire the core volume density and the velocity information of at least one core sample; The stiffness coefficient determination module is used to determine the stiffness coefficient based on the core bulk density and the velocity information of at least one core sample. The stiffness coefficient determination module includes: A velocity determination unit is used to determine the P-wave velocity in three directions associated with the bedding direction and the S-wave velocity in two directions associated with the bedding direction based on the velocity information of at least one core sample; specifically, the velocity determination unit is used to determine the P-wave velocity perpendicular to the bedding direction, the P-wave velocity parallel to the bedding direction, the S-wave velocity perpendicular to the bedding direction, the S-wave velocity parallel to the bedding direction, and the P-wave velocity at a 45° angle to the bedding direction based on the velocity information of at least one core sample. The stiffness coefficient calculation unit is used to calculate the stiffness coefficient based on the core bulk density, the longitudinal wave velocity in three directions associated with the bedding direction, and the transverse wave velocity in two directions associated with the bedding direction. The stiffness coefficient calculation unit includes: The first stiffness coefficient calculation subunit is used to calculate the first stiffness coefficient based on the core bulk density and the longitudinal wave velocity parallel to the bedding direction. The second stiffness coefficient calculation subunit is used to calculate the second stiffness coefficient based on the core bulk density and the longitudinal wave velocity perpendicular to the bedding direction. The third stiffness coefficient calculation subunit is used to calculate the third stiffness coefficient based on the core bulk density and the transverse wave velocity perpendicular to the bedding direction. The fourth stiffness coefficient calculation subunit is used to calculate the fourth stiffness coefficient based on the core bulk density and the transverse wave velocity parallel to the bedding direction. The fifth rigidity coefficient calculation subunit is used to calculate the fifth rigidity coefficient based on the first rigidity coefficient and the fourth rigidity coefficient; The sixth rigidity coefficient calculation subunit is used to calculate the sixth rigidity coefficient based on the core bulk density, the first rigidity coefficient, the second rigidity coefficient, the third rigidity coefficient, and the longitudinal wave velocity at a 45° angle to the bedding direction. The stiffness coefficient is an element in the stiffness coefficient matrix, represented as follows: , Indicates the row where the element is located. Indicates the column where the element is located; The formula for calculating the first stiffness coefficient is: ; The formula for calculating the second stiffness coefficient is: ; The formula for calculating the third stiffness coefficient is as follows: ; The formula for calculating the fourth stiffness coefficient is as follows: ; The formula for calculating the fifth stiffness coefficient is as follows: ; The formula for calculating the sixth stiffness coefficient is as follows: ; in, Indicates the bulk density of the rock core. This represents the longitudinal wave velocity parallel to the bedding direction. This represents the longitudinal wave velocity perpendicular to the bedding direction. This represents the transverse wave velocity perpendicular to the bedding direction. This represents the transverse wave velocity parallel to the bedding direction. This indicates the longitudinal wave velocity at a 45° angle to the bedding direction; The horizontal principal stress determination module is used to determine the horizontal principal stress of anisotropic rocks based on the stiffness coefficient, the pre-calculated overburden pressure, and the strain information obtained from differential strain experiments. The horizontal principal stress determination module includes: The parameter group determination unit is used to determine a first parameter group and a second parameter group based on a first stiffness coefficient, a second stiffness coefficient, a fifth stiffness coefficient, and a sixth stiffness coefficient; wherein, the first parameter group is associated with the maximum horizontal principal stress; and the second parameter group is associated with the minimum horizontal principal stress. The horizontal principal stress determination unit is used to determine the maximum and minimum horizontal principal stresses based on the first parameter set, the second parameter set, the overburden pressure, and strain information; wherein, the strain information includes the strain matched by the overburden pressure, the strain matched by the maximum horizontal principal stress, and the strain matched by the minimum horizontal principal stress. The first parameter group includes , , , and The second parameter group includes , , , and ;in, , , , , and The calculation formulas are as follows: ; ; ; The formula for calculating the maximum horizontal principal stress is as follows: The formula for calculating the minimum horizontal principal stress is as follows: ; in, Indicates overlying pressure. This indicates the strain matched by the overlying pressure. This represents the strain at which the maximum horizontal principal stress is matched. This represents the strain at minimum horizontal principal stress matching.

3. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor to enable the at least one processor to perform the method for determining the horizontal principal stress of anisotropic rocks as described in claim 1.

4. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the method for determining the horizontal principal stress of anisotropic rocks as described in claim 1.

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