Horizontal well casing cementing maximum horizontal principal stress inversion method and device and medium

Abstract

The invention provides a horizontal well casing cementing maximum horizontal principal stress inversion method and device and a medium, and belongs to the technical field of oil and gas exploration and development. The method comprises the following steps: setting a maximum horizontal principal stress as a trial value; calculating the maximum principal stress at the perforation hole according to the trial value; calculating an error value between the maximum principal stress at the perforation hole and the tensile strength of the rock; whether the error value is smaller than a set value or not is judged, and if yes, the trial value serves as the maximum horizontal principal stress obtained through inversion. The method is suitable for calculating the maximum horizontal principal stress under the horizontal well casing cementing perforation condition, and a technical means is provided for geological cognition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas exploration and development, and particularly relates to a horizontal well casing cementing maximum horizontal principal stress inversion method, device and medium. BACKGROUND

[0002] The shale gas resource potential in China is very huge, and the recoverable resource amount is about 26*10 12 m 3 , which is roughly equivalent to that of the United States. Only the Cambrian and Silurian systems of the Sichuan Basin, the resource amount of which is equivalent to 1.5-2.5 times the conventional natural gas resource amount of the basin, has a huge development potential. However, the shale oil and gas geological conditions in China are complex, and the reservoir types are various, among which, the difference in the horizontal principal stress affects the complexity of the fracturing network, and then directly relates to the fracturing reconstruction effect. Therefore, in order to improve the rationality of the fracturing design parameters, it is necessary to improve the accuracy of the understanding of the horizontal principal stress.

[0003] At present, with the development of exploration and development, the in-situ stress calculated on the basis of hydrostatic pressure theory is quite different from the measured in-situ stress, and it is necessary to obtain accurate in-situ stress by field inversion and other measurement methods for reference to correct the theoretical model. At present, the in-situ stress is often measured by the hydraulic fracturing method, that is, the high-pressure pump is used to pressurize and fracture the test section through the high-pressure pipeline. During the pressurization process, the rock in the fracturing section will break at the position of the minimum tangential stress under the action of hydraulic pressure, and the pressurization is continued until complete fracture. During the test, it is necessary to be in the open hole, and the borehole axis is parallel to the direction of one principal stress component in the rock. However, in the development of unconventional reservoirs such as shale oil and gas, the well type is mostly horizontal well casing cementing, and the angle between the borehole axis and the principal stress component exists, therefore, the conventional hydraulic fracturing stress measurement is not completely applicable to the horizontal well casing. SUMMARY

[0004] The purpose of the present application is to solve the problems existing in the prior art, and to provide a horizontal well casing cementing maximum horizontal principal stress inversion method, device and medium, which can invert the horizontal principal stress under the conditions of horizontal well casing cementing perforation fracturing, and provide a technical means for geological understanding.

[0005] The present application is realized by the following technical solutions:

[0006] In a first aspect, the present application provides a horizontal well casing cementing maximum horizontal principal stress inversion method, comprising:

[0007] A maximum horizontal principal stress is set as a trial value;

[0008] The maximum principal stress at the perforation hole is calculated according to the trial value;

[0009] Calculate the error value of the maximum principal stress at the perforation hole and the tensile strength of the rock;

[0010] Determine whether the error value is less than the set value, and if so, the trial value is used as the maximum horizontal principal stress obtained by inversion.

[0011] The further improvement of the present application is:

[0012] If it is determined that the error value is greater than or equal to the set value, the update value of the maximum horizontal principal stress is calculated according to the trial value, and the update value is used as the trial value to calculate the maximum principal stress at the perforation hole.

[0013] The further improvement of the present application is:

[0014] The update value of the maximum horizontal principal stress is calculated according to the trial value, and the specific calculation formula is:

[0015] F' = ((σ max (σ H + Δσ) - σ t )-(σ max (σ H )-σ t ) / Δσ

[0016]

[0017] In the formula, σ H is the trial value of the maximum horizontal principal stress, Pa; σ max (σ H ) is the maximum principal stress at the perforation hole calculated according to the trial value, Pa; Δσ is the step, Pa; σ t is the tensile strength of the shale, Pa; σ H 更新 is the update value of the maximum horizontal principal stress, Pa; F' is the calculation process factor, which has no real meaning.

[0018] The further improvement of the present application is:

[0019] The maximum principal stress at the perforation hole is calculated according to the trial value, and the specific operation includes:

[0020] Obtain the fracturing operation data and rock mechanics data;

[0021] Calculate the stress components at the perforation hole;

[0022] The maximum principal stress at the perforation hole is calculated according to the stress components at the perforation hole.

[0023] The further improvement of the present application is:

[0024] The fracturing operation data and rock mechanics data include: casing elastic modulus, casing Poisson's ratio, cement sheath elastic modulus, cement sheath Poisson's ratio, formation elastic modulus, formation Poisson's ratio, ground stress direction and vertical principal stress.

[0025] The further improvement of the present application is:

[0026] The calculation of the stress components at the perforation hole includes:

[0027] The casing inner diameter is r1, the casing outer diameter is r2, the wellbore radius is r3, the formation radius is r4, and the wellbore pressure is p;

[0028] According to the theory of elasticity, the stress function of the casing-cement sheath in the non-uniform stress field is set as Ariy's stress function:

[0029]

[0030] In formula (1): Ariy's stress function; r is the polar coordinate parameter, m; θ is the polar coordinate parameter, radian; A, B, C, D, K, F, M and H are unknown quantities to be solved in calculation, respectively;

[0031] Correspondingly, the stress components are:

[0032]

[0033] In formula (2), σ r is the radial stress, Pa; σ θ is the circumferential stress, Pa; τ rθ is the tangential stress, Pa;

[0034] Substituting formula (2) into formula (1), the stress component expressions of the casing, cement sheath and formation are obtained:

[0035]

[0036] In formula (3), B i , C i , K i , F i , M i , H i are unknown parameters in the casing, cement sheath and formation, respectively, i=1, 2, 3, corresponding to the casing, cement sheath and formation, respectively;

[0037] The geometric equation in polar coordinates is:

[0038]

[0039] In formula (4), ε riεi, i = 1, 2, 3, are the radial strain, non-dimensional, i = 1, 2, 3 correspond to casing, cement sheath, formation respectively; θi γi, i = 1, 2, 3, are the circumferential strain, non-dimensional, i = 1, 2, 3 correspond to casing, cement sheath, formation respectively; rθi τi, i = 1, 2, 3, are the tangential strain, non-dimensional, i = 1, 2, 3 correspond to casing, cement sheath, formation respectively;

[0040] The mechanical equation of plane strain is:

[0041]

[0042] In formula (4), Ei, i = 1, 2, 3, are the elastic modulus, i = 1, 2, 3 correspond to casing, cement sheath, formation respectively; vi, i = 1, 2, 3, are the Poisson's ratio, i = 1, 2, 3 correspond to casing, cement sheath, formation respectively; i i

[0043] Substitute formula (3) and formula (5) into formula (4), integrate and simplify to obtain:

[0044]

[0045] In formula (6), Ui, i = 1, 2, 3, are the radial displacement, m; γi, i = 1, 2, 3, are the circumferential displacement, m; i = 1, 2, 3 correspond to casing, cement sheath, formation respectively; ri θi

[0046] At r = r1, the boundary condition is:

[0047]

[0048] In formula (7), P is the pressure at casing, Pa, that is, the bottom hole fracture pressure; w

[0049] At r = r2, the boundary condition is:

[0050]

[0051] At r = r3, the boundary condition is:

[0052]

[0053] At r = r4, the boundary condition is:

[0054]

[0055] In formula (10), σi, i = 1, 2, 3, are the stress values under the action of far-field stress, when the well inclination angle is 90°:

[0056] ​​​​​​

[0057] In formula (11), σ h is the minimum horizontal principal stress; σ H is the trial value of the maximum horizontal principal stress; and α is the included angle between the minimum horizontal principal stress and the wellbore direction.

[0058] Substitute formula (2) and (5) into formula (6)-(11) to obtain the unknown parameters in formula (3), i.e. to obtain the stress distribution law at the cement sheath-stratigraphic interface;

[0059] The perforation hole is regarded as a small open hole wellbore connected with the wellbore wall surface, which is subjected to horizontal stress in the wellbore axis direction, and the horizontal force is σ rw , σ θw and σ zw , and the stress value at the perforation hole is obtained according to formula (3);

[0060] Suppose that the perforation radius is r p , and a cylindrical coordinate system is established with the hole axis as the reference , and σ θw is defined as the initial direction of the perforation circumferential angle , and the wellbore wall rock stress is regarded as the far-field stress of the hole, the stress distribution model of the perforation hole wall rock is obtained by calculating the stress components of the perforation hole and applying the superposition principle, in the same way as the above-mentioned method of analyzing the stress distribution of the wellbore wall rock;

[0061]

[0062] In formula (12), p p is the pore pressure, Pa; θ is the perforation circumferential angle; σ ρp , σ zp , τ ρzp , are the stress components of the perforation hole in the cylindrical coordinate system with the hole axis direction as the z direction, Pa; v3 is the Poisson's ratio of the stratum; P w is the casing pressure, Pa, i.e. the bottom hole fracture pressure; φ is the porosity of the stratum, dimensionless; σ rw , σ θw , σ zw τ θzw , τ θrw , τ rzw are the stress components of the perforation hole in the cylindrical coordinate system with the hole axis direction as the z direction, Pa.

[0063] Further improvement of the present application is that:

[0064] The maximum principal stress at the perforation hole is calculated according to each stress component at the perforation hole, and the specific operation comprises:

[0065] The three principal stresses at the perforation hole of the horizontal well are calculated by using the formula:

[0066]

[0067] In the formula, σ ρp , σ zp , are each stress component of the perforation hole in the direction of the cylindrical coordinate system with the hole axis direction as the z direction, Pa; σ1, σ2 and σ3 are the first, second and third principal stresses at the perforation hole of the horizontal well, Pa;

[0068] The maximum principal stress at the perforation hole is:

[0069] σ max (σ H ) = max (σ1, σ2, σ3).

[0070] The second aspect of the present application provides a horizontal well casing cementing maximum horizontal principal stress inversion device, comprising:

[0071] A setting unit is configured to set a maximum horizontal principal stress as a trial value;

[0072] A first calculation unit is configured to calculate the maximum principal stress at the perforation hole according to the trial value;

[0073] A second calculation unit is configured to calculate the error value of the maximum principal stress at the perforation hole and the tensile strength of the rock;

[0074] A judgment unit is configured to judge whether the error value is less than a set value;

[0075] An output unit is configured to output the trial value as the inverted maximum horizontal principal stress when the error value is less than the set value.

[0076] The further improvement of the present application is:

[0077] The first calculation unit comprises:

[0078] An acquisition subunit is configured to acquire fracturing operation data and rock mechanics data;

[0079] A perforation hole stress component calculation subunit is configured to calculate each stress component at the perforation hole;

[0080] A perforation hole maximum principal stress calculation subunit is configured to calculate the maximum principal stress at the perforation hole according to each stress component at the perforation hole.

[0081] In a third aspect, the present application provides a computer readable storage medium, which stores at least one program executable by a computer, and the at least one program, when executed by the computer, causes the computer to perform the steps of the method for calculating the maximum horizontal principal stress in the horizontal well casing cementing.

[0082] Compared with the prior art, the present application has the following beneficial effects:

[0083] The present application first sets a maximum horizontal principal stress as a trial value, calculates the maximum principal stress at the perforation hole according to the trial value, calculates the error value of the maximum principal stress at the perforation hole and the tensile strength of the rock, if the error value is less than the set value, the trial value is taken as the inverted maximum horizontal principal stress, if the error value is greater than or equal to the set value, the updated value of the maximum horizontal principal stress is calculated according to the trial value, the updated value is taken as the trial value, and the maximum principal stress at the perforation hole is recalculated until the error value of the maximum principal stress at the perforation hole and the tensile strength of the rock is less than the set value. The present application is suitable for calculating the maximum horizontal principal stress under the perforation condition of horizontal well casing cementing, and provides a technical means for geological understanding. BRIEF DESCRIPTION OF DRAWINGS

[0084] Figure 1 is a flow chart of a method for calculating the maximum horizontal principal stress in the horizontal well casing cementing of the present application;

[0085] Figure 2 is a structural diagram of a device for calculating the maximum horizontal principal stress in the horizontal well casing cementing of the present application. DETAILED DESCRIPTION

[0086] The present application will be further described in detail below in combination with the drawings:

[0087] At present, the in-situ geostress is measured by the hydraulic fracturing method, and during the test, it is required to be in the open hole, and the borehole axis is parallel to the direction of a principal stress component in the rock. However, in the development of unconventional reservoirs such as shale oil and gas, the well type is mostly horizontal well casing cementing, and the borehole axis and the principal stress component both have an included angle, therefore, the conventional hydraulic fracturing method for stress measurement is not completely applicable to the horizontal well casing. Based on this, the present application provides a method for inverting the horizontal principal stress, which first inverts the minimum horizontal principal stress according to the pump shutdown pressure drop data, and then inverts the maximum horizontal principal stress according to the fracture pressure and the minimum horizontal principal stress, and is suitable for calculating the maximum horizontal principal stress under the perforation condition of horizontal well casing cementing, and provides a technical means for geological understanding.

[0088]

Example 1

[0089] As shown in Figure 1 , the present application provides a method for inverting the maximum horizontal principal stress in the horizontal well casing cementing, which comprises:

[0090] First, set a maximum horizontal principal stress as a trial value;

[0091] Second, calculate the maximum principal stress at the perforation hole according to the trial value;

[0092] Third, calculate the error value of the maximum principal stress at the perforation hole and the tensile strength of the rock,

[0093]

[0094] Fourth, determine whether the error value is less than the set value (the set value is set according to the required accuracy, for example, the set value can be 1% or less), if yes, go to the sixth step, if no, go to the fifth step;

[0095] Fifth, obtain an updated value of the maximum horizontal principal stress, and take the updated value as the trial value, and then return to the second step;

[0096] Sixth, take the trial value as the maximum horizontal principal stress obtained by inversion.

[0097] The present application is applicable to the calculation of the maximum horizontal principal stress under the condition of perforation of casing cementing in horizontal wells, and provides a technical means for geological understanding.

[0098] Example 2

[0099] In the fifth step, the updated value of the maximum horizontal principal stress is obtained, and the specific calculation formula is:

[0100]

[0101] Wherein, σ H is the trial value of the maximum horizontal principal stress, Pa; σ max (σ H ) is the maximum principal stress at the perforation hole calculated according to the trial value, Pa; Δσ is the step length, Pa; σ t is the tensile strength of shale, Pa; σ H 更新 is the updated value of the maximum horizontal principal stress, Pa; F' is a factor in the calculation process, which has no real meaning.

[0102] Example 3

[0103] In the second step, the maximum principal stress at the perforation hole is calculated according to the trial value, and the specific operation includes:

[0104] Step 201, obtaining fracturing operation data and rock mechanics data, specifically:

[0105] The fracturing operation data and rock mechanics data include: casing elastic modulus, casing Poisson's ratio, cement sheath elastic modulus, cement sheath Poisson's ratio, formation elastic modulus, formation Poisson's ratio, ground stress direction and vertical principal stress.

[0106] Wherein, the casing elastic modulus, casing Poisson's ratio, cement sheath elastic modulus and cement sheath Poisson's ratio can be obtained by experiment; the formation elastic modulus and formation Poisson's ratio can be obtained by experiment or well logging interpretation; the ground stress direction and vertical principal stress can be obtained by well logging and acoustic emission experiment, and the above experimental methods are prior art and will not be described here.

[0107] Step 202, calculating each stress component at the perforation hole; the specific operation includes:

[0108] Let the casing inner diameter be r1, the casing outer diameter be r2, the wellbore radius be r3, the formation radius be r4, and the wellbore pressure be p;

[0109] According to the theory of elasticity, the stress function of the casing-cement sheath in the non-uniform stress field is set as Ariy's stress function:

[0110]

[0111] In formula (1): Ariy's stress function; r is the polar coordinate parameter, m; θ is the polar coordinate parameter, radian; A, B, C, D, K, F, M and H are unknown quantities to be solved in calculation, respectively;

[0112] Correspondingly, the stress component is:

[0113]

[0114] In formula (2), σ r is the radial stress, Pa; σ θ is the circumferential stress, Pa; τ rθ is the tangential stress, Pa;

[0115] Substitute formula (2) into formula (1) to obtain the expression of each stress component of the casing, cement sheath and formation:

[0116]

[0117] In formula (3), B i , C i , K i , F i , M i , H i are unknown parameters in the casing, cement sheath and formation, respectively, i=1, 2, 3, corresponding to the casing, cement sheath and formation, respectively;

[0118] The geometric equation in polar coordinates is:

[0119]

[0120] In formula (4), ε ri is a radial strain, dimensionless, i = 1, 2, 3 respectively corresponding to the casing, cement sheath, and formation; ε θi is a circumferential strain, dimensionless, i = 1, 2, 3 respectively corresponding to the casing, cement sheath, and formation; γ rθi is a tangential strain, dimensionless, i = 1, 2, 3 respectively corresponding to the casing, cement sheath, and formation;

[0121] The mechanical equation of plane strain is:

[0122]

[0123] In formula (4), E i is an elastic modulus, i = 1, 2, 3, respectively corresponding to the casing, cement sheath, and formation; v i is a Poisson's ratio, i = 1, 2, 3, respectively corresponding to the casing, cement sheath, and formation;

[0124] Substitute formula (3) and formula (5) into formula (4), integrate and simplify to obtain:

[0125]

[0126] In formula (6), U ri is a radial displacement, m; U θi is a circumferential displacement, m; i = 1, 2, 3 respectively corresponding to the casing, cement sheath, and formation;

[0127] At r = r1, the boundary condition is:

[0128]

[0129] In formula (7), P w is a pressure at the casing, Pa, i.e., a bottom hole fracture pressure, which can be obtained through construction data;

[0130] At r = r2, the boundary condition is:

[0131]

[0132] At r = r3, the boundary condition is:

[0133]

[0134] At r = r4, the boundary condition is:

[0135]

[0136] In formula (10), is the stress value under the far-field stress, when the hole angle is 90°:

[0137]

[0138] In formula (11), σ h is the minimum horizontal principal stress; σ H is the trial value of the maximum horizontal principal stress; and α is the included angle between the minimum horizontal principal stress and the wellbore direction.

[0139] The minimum horizontal principal stress σ h may be obtained by inversion according to the pump-off pressure drop data, and the specific operation includes: obtaining the pressure after pump-off and the construction time, drawing the curves of pressure and G function and Gdp / dG and G function respectively, and obtaining the closure pressure, i.e. the minimum horizontal principal stress, according to the changes of the two curves. The minimum horizontal principal stress σ h is obtained by inversion according to the pump-off pressure drop data, and the specific operation includes: obtaining the pressure after pump-off and the construction time, drawing the curves of pressure and G function and Gdp / dG and G function respectively, and obtaining the closure pressure, i.e. the minimum horizontal principal stress, according to the changes of the two curves.

[0140] Substituting formula (2) and (5) into formula (6)-(11) to obtain the unknown parameters in formula (3), i.e. to obtain the stress distribution law at the cement sheath-stratigraphic interface;

[0141] The perforation hole is regarded as a small open hole wellbore connected with the wellbore wall surface, which is subjected to horizontal stress in the wellbore axis direction, and the horizontal force is σ rw , σ θw and σ zw . The stress value at the perforation hole is obtained according to formula (3);

[0142] Supposing that the perforation radius is r p , a cylindrical coordinate system is established with the hole axis as the reference , and σ θw is defined as the initial direction of the perforation circumferential angle . The same as the above analysis method of the stress distribution of the wellbore surrounding rock, the stress components of the wellbore surrounding rock are regarded as the far-field stress of the hole, and the stress distribution model of the perforation hole surrounding rock is obtained after the calculation of the stress components of the perforation hole:

[0143]

[0144] In formula (12), p p is the pore pressure, Pa; is the perforation circumferential angle; σ ρp , σ zp , τ ρzp , respectively are each stress component of the perforation hole in the cylindrical coordinate system with the hole axis direction as the z direction, Pa; v3 is the formation Poisson's ratio; P w is the casing pressure, Pa, i.e., the bottom hole fracture pressure; φ is the formation porosity, dimensionless; σ rw , σ θw , σ zw τ θzw , τ θrw , τ rzw respectively are each stress component of the perforation hole in the cylindrical coordinate system with the hole axis direction as the z direction, Pa.

[0145] In step 203, the maximum principal stress at the perforation hole is calculated according to each stress component at the perforation hole

[0146] The specific operation includes:

[0147] The three principal stresses at the perforation hole of the horizontal well are calculated by using the formula:

[0148]

[0149] wherein, σ ρp , σ zp , and σ respectively are each stress component of the perforation hole in the cylindrical coordinate system with the hole axis direction as the z direction, Pa; σ1, σ2 and σ3 respectively are the first, second and third principal stresses at the perforation hole of the horizontal well, Pa;

[0150] The maximum principal stress at the perforation hole is:

[0151] σ max (σ H ) = max (σ1, σ2, σ3).

[0152]

Example 4

[0153] In this example, the maximum horizontal principal stress of a shale gas well in the southwest of Sichuan is inversed by using the horizontal well casing cementing maximum horizontal principal stress inversion method of the present application, so as to further explain the method of the present application.

[0154] A shale gas well in the southwest of Sichuan province has a vertical depth of 4336.20 m, and the breakdown pressure is 135.3 MPa at the well bottom. According to the rock mechanics experiment results, the rock tensile strength is 14.28 MPa, and the minimum horizontal principal stress is 110.9 MPa according to the pressure drop analysis results. On this basis, the maximum principal stress at the perforation hole is calculated according to different maximum horizontal principal stresses. When the maximum horizontal principal stress is 129.2 MPa, the maximum principal stress at the perforation hole is 14.29 MPa, which is close to the rock tensile strength. According to the rock tensile strength criterion, the maximum horizontal principal stress is 129.2 MPa, and the horizontal principal stress difference is 18.3 MPa. According to the acoustic emission experiment results, the two-way horizontal principal stress difference is 17.5 MPa, and the experimental results are basically consistent with the measured values.

[0155] Example 5

[0156] The embodiment of the present application provides a horizontal well casing cementing maximum horizontal principal stress inversion device, as shown in the figure, comprising: Figure 2

[0157] The setting unit is used for setting a maximum horizontal principal stress as a trial value;

[0158] The first calculation unit is used for calculating the maximum principal stress at the perforation hole according to the trial value;

[0159] The second calculation unit is used for calculating the error value of the maximum principal stress at the perforation hole and the rock tensile strength;

[0160] The judgment unit is used for judging whether the error value is less than the set value;

[0161] The output unit is used for outputting the trial value as the inversion maximum horizontal principal stress when the error value is less than the error set value;

[0162] The update value acquisition unit is used for acquiring the update value of the maximum horizontal principal stress according to the trial value when the error value is greater than or equal to the error set value, and taking the update value as the trial value to calculate the maximum principal stress at the perforation hole.

[0163] The first calculation unit comprises:

[0164] The acquisition subunit is used for acquiring the fracturing construction data and the rock mechanics data;

[0165] The perforation hole stress component calculation subunit is used for calculating the stress components at the perforation hole;

[0166] The perforation hole maximum principal stress calculation subunit is used for calculating the maximum principal stress at the perforation hole according to the stress components at the perforation hole.

[0167] Example 6​

[0168] The embodiment of the present application further provides a computer readable storage medium, which stores at least one program executable by a computer, and the at least one program enables the computer to execute the steps in the horizontal well casing cementing maximum horizontal principal stress inversion method when the at least one program is executed by the computer.

[0169] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing related hardware, and the program can be stored in a non-volatile computer readable storage medium. When the program is executed, the program can include the processes of the above-mentioned embodiment methods. Any reference to memory, storage, database or other medium used in each embodiment provided by the present application can include non-volatile and / or volatile memory. The non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. The volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM) and memory bus dynamic RAM (RDRAM).

[0170] The above technical solutions are only one embodiment of the present application. For those skilled in the art, on the basis of the disclosed principles of the present application, various types of improvements or modifications can be easily made, and are not limited to the technical solutions described in the above-mentioned specific embodiments. Therefore, the above description is only preferred, and is not limited in nature.

Claims

1. A method for inverting the maximum horizontal principal stress in horizontal well casing cementing, characterized in that, include: Set a maximum horizontal principal stress as a trial value; The maximum principal stress at the perforation hole was calculated based on the trial values. Calculate the error between the maximum principal stress at the perforation hole and the tensile strength of the rock; Determine if the error value is less than the set value. If so, use the trial value as the maximum horizontal principal stress obtained by inversion.

2. The method according to claim 1, characterized in that, If the judgment error value is greater than or equal to the set value, the updated value of the maximum horizontal principal stress is calculated based on the trial value. The updated value is then used as the trial value to calculate the maximum principal stress at the perforation hole.

3. The method according to claim 2, characterized in that, The updated value of the maximum horizontal principal stress is calculated based on the trial values. The specific calculation formula is as follows: F'=((σ max (s H +Δσ)-σ t )-(s max (s H )-s t )) / Boss In the formula, σ H The calculated value of the maximum horizontal principal stress is given in Pa; σ max (σ H ) represents the maximum principal stress at the perforation hole calculated from trial values, in Pa; Δσ is the step size, in Pa; σ t σ is the tensile strength of shale, Pa; H 更新 The updated value of the maximum horizontal principal stress, in Pa; F' is a factor in the calculation process and has no real meaning.

4. The method according to claim 1, characterized in that, The maximum principal stress at the perforation hole was calculated based on the trial values. The specific steps included: Obtain fracturing construction data and rock mechanics data; Calculate the stress components at the perforation hole; The maximum principal stress at the perforation hole was calculated based on the stress components at each perforation hole.

5. The method according to claim 4, characterized in that, The fracturing construction data and rock mechanics data include: casing elastic modulus, casing Poisson's ratio, cement sheath elastic modulus, cement sheath Poisson's ratio, formation elastic modulus, formation Poisson's ratio, geostress direction, and vertical principal stress.

6. The method according to claim 4, characterized in that, The specific steps for calculating the stress components at the perforation hole include: Let the inner diameter of the casing be r1, the outer diameter of the casing be r2, the wellbore radius be r3, the formation radius be r4, and the wellbore pressure be p; Based on the theory of elasticity and Ariy's stress function, let the stress function of the sleeve-cement ring in a non-uniform stress field be: In formula (1): Let be Ariy's stress function; r be the polar coordinate parameter in m; θ be the polar coordinate parameter in radians; A, B, C, D, K, F, M and H are the unknowns to be solved in the calculation. Correspondingly, its stress components are: In equation (2), σ r Radial stress, Pa; σ θ For circumferential stress, Pa; τ rθ The stress is tangential, Pa; Substituting equation (2) into equation (1), we obtain the expressions for the stress components of the casing, cement sheath, and formation as follows: In equation (3), B i C i K i F i M i H i These are the unknown parameters in the casing, cement sheath, and formation, respectively, where i = 1, 2, 3, corresponding to the casing, cement sheath, and formation, respectively. The geometric equation in polar coordinates is: In equation (4), ε ri For radial strain, dimensionless, i = 1, 2, 3 correspond to casing, cement sheath, and formation, respectively; ε θi For circumferential strain, dimensionless, i = 1, 2, 3 correspond to casing, cement sheath, and formation, respectively; γ rθi The strain is tangential and dimensionless; i = 1, 2, 3 correspond to the casing, cement sheath, and formation, respectively. The mechanical equation for plane strain is: In equation (4), E i v represents the elastic modulus, where i = 1, 2, 3, corresponding to the casing, cement sheath, and formation, respectively; i Let i be Poisson's ratio, and i = 1, 2, 3, which correspond to casing, cement sheath, and formation, respectively. Substituting equations (3) and (5) into equation (4), integrating and simplifying, we get: In equation (6), U ri U represents radial displacement, in meters (m); θi The displacement is circumferential, m; i = 1, 2, 3 correspond to the casing, cement sheath, and formation, respectively; At r = r1, the boundary conditions are: In equation (7), P w The pressure at the casing, in Pa, is the bottom hole fracture pressure. At r = r2, the boundary conditions are: At r = r3, the boundary conditions are: At r = r4, the boundary conditions are: In equation (10), The stress value is the value under the action of far-field stress when the well inclination angle is 90°: In equation (11), σ h σ is the minimum horizontal principal stress; H α is the calculated value of the maximum horizontal principal stress; α is the angle between the minimum horizontal principal stress and the wellbore direction. Substituting equations (2) and (5) into equations (6) to (11) yields the unknown parameters in equation (3), thus obtaining the stress distribution law at the cement sheath-formation interface. The perforation hole is considered as a small open-hole wellbore connected to the wellbore wall. It is subjected to horizontal stress along the wellbore axis, and the horizontal force is σ. rw σ θw and σ zw The stress value at the perforation hole is obtained according to equation (3); Let the radius of the perforation be r. p Establish a cylindrical coordinate system based on the axis of the hole. And define σ θw The direction is the circumferential angle of the perforation. The starting position is the same as the method used to analyze the stress distribution of the surrounding rock in the horizontal wellbore described above. The stress components of the surrounding rock in the wellbore are regarded as the far-field stress of the perforation. After calculating each stress component of the perforation, the superposition principle is applied to obtain the stress distribution model of the surrounding rock of the perforation: In equation (12), p p Pore ​​pressure, Pa; σ is the circumferential angle of the perforation; ρp , σ zp , τ ρzp , These represent the stress components of the perforation hole in a cylindrical coordinate system with the hole axis as the z-direction, in Pa; v3 is the formation Poisson's ratio; P w σ represents the pressure at the casing, in Pa, i.e., the bottom hole fracture pressure; φ represents the formation porosity, which is dimensionless; σ rw σ θw σ zw τ θzw τ θrw τ rzw These are the stress components at the perforation hole in a cylindrical coordinate system with the wellbore axis as the z-direction, in Pa.

7. The method according to claim 4, characterized in that, The maximum principal stress at the perforation hole is calculated based on the stress components at the perforation hole. The specific operation includes: The three principal stresses at the perforation hole of the horizontal well were calculated using the formula: In the formula, σ ρp , σ zp , σ1, σ2, and σ3 are the stress components of the perforation hole in the cylindrical coordinate system with the hole axis as the z-direction, respectively, in Pa; σ1, σ2, and σ3 are the first, second, and third principal stresses at the perforation hole of the horizontal well, respectively, in Pa. The maximum principal stress at the perforation hole is: s max (s H )=max(σ1,σ2,σ3).

8. A device for inverting the maximum horizontal principal stress in horizontal well casing cementing, characterized in that, include: The setting unit is used to set a maximum horizontal principal stress as a trial value; The first calculation unit is used to calculate the maximum principal stress at the perforation hole based on the trial values. The second calculation unit is used to calculate the error between the maximum principal stress at the perforation hole and the tensile strength of the rock. The judgment unit is used to determine whether the error value is less than the set value; The output unit is used to output the calculated value as the maximum horizontal principal stress obtained by inversion when the error value is less than the set value.

9. The apparatus according to claim 8, characterized in that, The first computing unit includes: Acquire sub-units to obtain fracturing construction data and rock mechanics data; The sub-unit for calculating stress components at the perforation hole is used to calculate each stress component at the perforation hole. The maximum principal stress calculation sub-unit at the perforation hole is used to calculate the maximum principal stress at the perforation hole based on the stress components at the perforation hole.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the method for inverting the maximum horizontal principal stress in horizontal well casing cementing as described in any one of claims 1-8.

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