Method and device for determining collapse pressure of well wall

Abstract

The present application discloses a method and device for determining the collapse pressure of a well wall, and belongs to the field of petrochemical industry. Since the computer equipment can output the collapse pressure at the point to be drilled according to the first principal stress, the second principal stress and the third principal stress determined by the in situ stress, the well inclination angle and the well inclination azimuth angle, the computer equipment can output the collapse pressure at the point to be drilled. Therefore, the drilling personnel can accurately determine whether the well wall will collapse when drilling at the point to be drilled based on the collapse pressure, thereby effectively improving the accuracy of determining whether the well wall collapses. In addition, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the well wall collapses is further improved.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry, and in particular to a method and device for determining the collapse pressure of a well wall. Background Art

[0002] During oil drilling, drillers usually determine based on experience whether the well wall will collapse if drilling is performed at a point to be drilled on the well wall. However, this method results in low reliability in determining whether the well wall collapses. Summary of the invention

[0003] The embodiment of the present disclosure provides a method and device for determining the collapse pressure of a well wall, which can solve the problem of low reliability in determining whether the well wall has collapsed in the related art. The technical solution is as follows:

[0004] In one aspect, a method for determining the collapse pressure of a well wall is provided, which is applied to a computer device, and the method comprises:

[0005] Obtaining the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall;

[0006] Determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth;

[0007] outputting the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress;

[0008] The directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other, and the collapse pressure is positively correlated with the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress.

[0009] The step of outputting the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress, and the third principal stress comprises:

[0010] Obtaining rock mechanics parameters at the point to be drilled, wherein the rock mechanics parameters include uniaxial compression strength, pore pressure, and overburden pressure;

[0011] Determine the triaxial compressive strength at the drilling point according to the pore pressure and the difference between the maximum principal stress and the minimum principal stress, wherein the triaxial compressive strength is positively correlated with the pore pressure, the maximum principal stress is the principal stress with the largest value among the first principal stress, the second principal stress and the third principal stress, and the minimum principal stress is the principal stress with the smallest value among the first principal stress, the second principal stress and the third principal stress;

[0012] The collapse pressure at the point to be drilled is determined according to the pore pressure, the overburden pressure, the intermediate principal stress and the triaxial compression strength, and the collapse pressure at the point to be drilled is output. The magnitude of the collapse pressure is also positively correlated with the magnitude of the pore pressure and the magnitude of the overburden pressure.

[0013] Optionally, the triaxial compression strength σ at the drilling point s satisfy:

[0014] Among them, the p 1 is the pore pressure, the Q 1 is the difference between the maximum principal stress and the minimum principal stress, and Q 2 is the uniaxial compression strength at the point to be drilled, and K is the influence coefficient of the confining pressure on the strength of the rock at the point to be drilled when the confining pressure at the point to be drilled is 0.

[0015] Optionally, the collapse pressure P1 satisfies: P1 = σ s +σ 1 ×f×e 1-f ,

[0016] Among them, the σ s is the triaxial compressive strength, the σ 1 is the intermediate principal stress, the p 1 is the pore pressure, the p 2 is the overburden pressure, and γ is a constant.

[0017] Optionally, determining the first principal stress, the second principal stress, and the third principal stress at the drilling point according to the in situ stress, the well inclination angle, and the well inclination azimuth includes:

[0018] Determine the first circumferential stress, the second circumferential stress, and the third circumferential stress at the drilling point in a cylindrical coordinate system according to the in situ stress, the well inclination angle, and the well inclination azimuth, wherein the plane where the polar coordinate system in the cylindrical coordinate system is located is a plane tangent to the well wall;

[0019] determining that the first principal stress is equal to the first circumferential stress;

[0020] determining the second principal stress and the third principal stress according to the second circumferential stress, the third circumferential stress and the circumferential shear force;

[0021] The magnitude of the second principal stress is negatively correlated with the magnitude of the circumferential shear force, and the magnitude of the third principal stress is positively correlated with the magnitudes of the second circumferential stress and the magnitudes of the circumferential shear force.

[0022] Optionally, the second principal stress σ k satisfy:

[0023] The third principal stress σ j satisfy:

[0024] Among them, the σ θ is the second circumferential stress, the σ z is the third circumferential stress, the τ θz is the circumferential shear force.

[0025] Optionally, after outputting the collapse pressure at the point to be drilled according to the first principal stress, the second principal stress and the third principal stress, the method further includes:

[0026] Obtaining a target pressure, wherein the target pressure is positively correlated with the minimum principal stress;

[0027] The difference between the target pressure and the collapse pressure is output, and the difference is used to indicate whether the well wall will collapse when drilling at the point to be drilled.

[0028] Optionally, the target pressure P2 satisfies:

[0029] Said is the internal friction angle of the rock at the point to be drilled, c is the cohesion of the rock at the point to be drilled, and σ 2 is the minimum principal stress.

[0030] On the other hand, a device for determining the collapse pressure of a well wall is provided, the device comprising:

[0031] An acquisition module, used for acquiring the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall;

[0032] A determination module, used to determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth;

[0033] An output module, configured to output the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress;

[0034] The directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other, and the collapse pressure is positively correlated with the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress.

[0035] On the other hand, a computer-readable storage medium is provided, in which instructions are stored, and the instructions are loaded and executed by a processor to implement the method for determining the collapse pressure of the well wall as described in the above aspects.

[0036] On the other hand, a computer device is provided, comprising: a memory, a processor and a computer program stored in the memory, wherein when the processor executes the computer program, the method for determining the collapse pressure of the well wall as described in the above aspects is implemented.

[0037] In yet another aspect, a computer program product comprising instructions is provided, and when the computer program product is run on the computer, the computer is caused to execute the method for determining the collapse pressure of the well wall as described in the above aspect.

[0038] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0039] The disclosed embodiment provides a method and device for determining the collapse pressure of a wellbore. Since the computer device can output the collapse pressure at the point to be drilled based on the first principal stress, the second principal stress and the third principal stress determined by the in situ stress, the well inclination angle and the well inclination azimuth, the wellbore driller can accurately determine whether the wellbore wall will collapse when drilling at the wellbore point based on the collapse pressure, thereby effectively improving the accuracy of determining whether the wellbore wall collapses. In addition, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the wellbore wall collapses is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 is a flow chart of a method for determining the collapse pressure of a well wall provided by an embodiment of the present disclosure;

[0042] Figure 2 is a flow chart of another method for determining the collapse pressure of a well wall provided by an embodiment of the present disclosure;

[0043] Figure 3 is a schematic diagram in a cylindrical coordinate system provided by an embodiment of the present disclosure;

[0044] Figure 4 It is a schematic diagram comparing a principal stress actually measured by an embodiment of the present disclosure with a principal stress determined by a method provided by an embodiment of the present application;

[0045] Figure 5 It is a change cloud diagram of collapse pressure determined by the method provided in the embodiment of the present application, provided in the embodiment of the present application;

[0046] Figure 6 It is a cloud diagram of the change of collapse pressure determined by the method provided by the relevant technology;

[0047] Figure 7 is a block diagram of a device for determining the collapse pressure of a well wall provided by an embodiment of the present disclosure;

[0048] Figure 8 It is a block diagram of another device for determining the collapse pressure of a well wall provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0050] Figure 1 1 is a flow chart of a method for determining the collapse pressure of a wellbore provided in an embodiment of the present disclosure. The method can be applied to a computer device, which can be a laptop computer, a desktop computer or other device with computing functions. Figure 1 As shown, the method may include:

[0051] Step 101: Obtain the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall.

[0052] In the disclosed embodiment, the in-situ stress, well inclination angle and well inclination azimuth can all be measured by a logging tool. The drilling personnel can store the in-situ stress, well inclination angle and well inclination azimuth measured by the logging tool in a computer device. Then the computer device can obtain the in-situ stress, well inclination angle and well inclination azimuth. Optionally, the logging tool may include a stress measuring device and an angle detector, the stress measuring device is used to measure the in-situ stress of the well wall, and the angle detector can be used to measure the well inclination angle and well inclination azimuth at the drilling point.

[0053] Step 102: Determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth.

[0054] After obtaining the in-situ stress, well inclination angle and well inclination azimuth, the computer equipment can determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in-situ stress, the well inclination angle and the well inclination azimuth.

[0055] The direction of the first principal stress, the direction of the second principal stress and the direction of the third principal stress are perpendicular to each other.

[0056] Step 103: output the collapse pressure at the drilling point according to the first principal stress, the second principal stress and the third principal stress.

[0057] After determining the first principal stress, the second principal stress and the third principal stress at the drilling point, the computer device can output the collapse pressure at the drilling point according to the first principal stress, the second principal stress and the third principal stress. The collapse pressure at the drilling point is the predicted pressure that the drilling point will bear when drilling the drilling point. Since this pressure may cause the collapse of the well wall, it is called collapse pressure.

[0058] This allows the driller to determine whether the well wall will collapse when drilling at the drilling point based on the collapse pressure. The magnitude of the collapse pressure is positively correlated with the magnitude of the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress, that is, the greater the intermediate principal stress, the greater the collapse pressure; the smaller the intermediate principal stress, the smaller the collapse pressure.

[0059] The computer device can determine the maximum principal stress, the intermediate principal stress and the minimum principal stress from the first principal stress, the second principal stress and the third principal stress. The maximum principal stress is the principal stress with the largest value among the first principal stress, the second principal stress and the third principal stress, the minimum principal stress is the principal stress with the smallest value among the first principal stress, the second principal stress and the third principal stress, and the intermediate principal stress is the principal stress other than the maximum principal stress and the minimum principal stress among the first principal stress, the second principal stress and the third principal stress.

[0060] In summary, the disclosed embodiment provides a method for determining the collapse pressure of a wellbore. Since the computer device can output the collapse pressure at the point to be drilled based on the first principal stress, the second principal stress, and the third principal stress determined by the in situ stress, the well inclination angle, and the well inclination azimuth, the wellbore driller can accurately determine whether the wellbore wall will collapse when drilling at the wellbore point based on the collapse pressure, thereby effectively improving the accuracy of determining whether the wellbore wall collapses. Moreover, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the wellbore wall collapses is further improved.

[0061] Figure 2 FIG. 1 is a flow chart of another method for determining the collapse pressure of a well wall provided by an embodiment of the present disclosure. The method can be applied to a computer device, which can be a laptop or a desktop computer. Figure 2 As shown, the method may include:

[0062] Step 201: Obtain the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall.

[0063] In the disclosed embodiment, the in-situ stress, well inclination angle and well inclination azimuth can be measured by a logging tool. The drilling personnel can store the in-situ stress, well inclination angle and well inclination azimuth measured by the logging tool in a computer device. Then the computer device can obtain the in-situ stress, well inclination angle and well inclination azimuth. Optionally, the logging tool may include a stress measuring device and an angle detector, the stress measuring device is used to measure the in-situ stress of the well wall, and the angle detector can be used to measure the well inclination angle and well inclination azimuth at the drilling point.

[0064] Wherein, the in-situ stress refers to the original magnitude of the in-situ stress in the formation before drilling, and the in-situ stress may include the maximum horizontal principal stress, the minimum horizontal principal stress, and the vertical principal stress. The direction of the maximum horizontal principal stress, the direction of the minimum horizontal principal stress, and the direction of the vertical principal stress are perpendicular to each other. Optionally, the in-situ stress may be the in-situ stress at the target formation depth, and for example, the formation depth may be 2050 meters (m).

[0065] refer to Figure 3 , the computer equipment can determine the maximum principal stress σ at this level in the three-dimensional rectangular coordinate system XYZ H , horizontal minimum principal stress σ h and the vertical principal stress σ v . In this three-dimensional rectangular coordinate system XYZ, the plane XY where the X-axis and Y-axis are located is parallel to the horizontal plane of the vertical well, and the Z-axis of the three-dimensional rectangular coordinate system XYZ is parallel to the vertical direction of the vertical well. The vertical well refers to a well whose designed trajectory is a plumb line. If the well 00 where the drilling point is located is an inclined well, refer to Figure 3 The well inclination angle α is the angle between the Z axis and the perpendicular bisector of well 00.

[0066] Step 202: Determine the first circumferential stress, the second circumferential stress, the third circumferential stress and the circumferential shear force at the drilling point in the cylindrical coordinate system according to the in situ stress, the well inclination angle and the well inclination azimuth.

[0067] After obtaining the in-situ stress, well inclination angle and well inclination azimuth, the computer equipment can determine the first circumferential stress, the second circumferential stress, the third circumferential stress and the circumferential shear force at the drilling point in the cylindrical coordinate system according to the in-situ stress, well inclination angle and well inclination azimuth. The plane where the polar coordinate system in the cylindrical coordinate system is located is the plane tangent to the well wall. Figure 3 The plane where the polar coordinate system (r, θ) in the cylindrical coordinate system is located is parallel to the plane where the wellhead of well 00 is located, and the z-axis of the cylindrical coordinate system is perpendicular to the polar coordinate system (r, θ).

[0068] Optionally, the computer device may first determine the first stress component, the second stress component, the third stress component, the first shear force component, the second shear force component and the third shear force component at the point to be drilled in the three-dimensional rectangular coordinate system XYZ according to the in situ stress, the well inclination angle and the well inclination azimuth. Afterwards, the computer device may determine the first circumferential stress, the second circumferential stress, the third circumferential stress and the circumferential shear force at the point to be drilled in the cylindrical coordinate system according to the first stress component, the second stress component, the third stress component, the first shear force component, the second shear force component and the third shear force component.

[0069] Among them, the direction of the first stress component is parallel to the X axis, the direction of the second stress component is parallel to the Y axis, and the direction of the third stress component is parallel to the Z axis. The first shear force component is the shear force in the plane where the X axis and the Y axis are located, the second shear force component is the shear force in the plane where the Y axis and the Z axis are located. The third shear force component is the shear force in the plane where the X axis and the Z axis are located.

[0070] Optionally, the first stress component σ X , the second stress component σ Y and the third stress component σ Z Satisfies the following formula:

[0071] σ X =σ H ×cos 2 α×cos 2 ω+σ h ×cos 2 α×sin 2 ω+σ v ×sin 2 α.

[0072] σ Y =σ H ×sin 2 ω+σ h ×cos 2 ω.

[0073] σ Z =σ H ×sin 2 α×cos 2 ω+σ h ×sin 2 α×sin 2 ω+σ v ×cos 2 α.

[0074] Here, ω is the well inclination azimuth.

[0075] The first shear force component τ XY , the second shear force component τYZ and the third shear force component τ XZ Satisfies the following formula:

[0076] τ XY =-σ H ×cosα×cosω×sinω+σ h ×cosα×cosω×sinω.

[0077] τ YZ =-σ H ×sinα×cosω×sinω+σ h ×sinα×cosω×sinω

[0078] τ XZ =σ H ×cosα×sinα×cos 2 ω+σ h ×cosα×sinα×sin 2 ω-H,

[0079] Among them, H = σ v ×cosα×sinα.

[0080] In the embodiment of the present disclosure, the first circumferential stress σ r The direction is parallel to the r-axis of the polar coordinate system. The second circumferential stress σ θ The direction is parallel to the θ axis of the polar coordinate system. The third circumferential stress σ z The direction is parallel to the z-axis of the cylindrical coordinate system. The circumferential shear force τ θz The direction is parallel to the plane where the z-axis and the θ-axis of the cylindrical coordinate system are located.

[0081] The first circumferential stress σ r , the second circumferential stress σ θ , the third circumferential stress σ z and circumferential shear force τ θz Satisfies the following formula:

[0082]

[0083]

[0084]

[0085]

[0086] Among them, the v is Poisson's ratio, R is the radius of the borehole at the drilling point, and r1 is the distance from the mid-perpendicular line of the well to any point on the well wall after the stress at the drilling point is released.1 can be the pore pressure at the point to be drilled, the p w can be the bottom hole fluid column pressure, and λ can be the effective stress coefficient. Figure 3 , where β can be the angle of a point on the well wall rotated counterclockwise along the x-axis direction, and β can satisfy Or, the Both R and r1 can be values ​​pre-stored in the computer device.

[0087] In the disclosed embodiment, the logging tool may further include: a pressure detector. The drilling personnel may store the pore pressure and bottom hole fluid column pressure at the drilling point measured by the pressure detector in a computer device, and the computer device may then obtain the pore pressure and bottom hole fluid column pressure at the drilling point.

[0088] Step 203: Determine that the first principal stress is equal to the first circumferential stress.

[0089] After determining the first circumferential stress, the computer device can determine that the first principal stress at the drilling point is equal to the first circumferential stress, that is, the first principal stress satisfies σ i :σ i =σ r .

[0090] Step 204: determine the second principal stress and the third principal stress according to the second circumferential stress, the third circumferential stress and the circumferential shear force.

[0091] After determining the second circumferential stress, the third circumferential stress and the circumferential shear force, the computer device can determine the second principal stress and the third principal stress according to the second circumferential stress, the third circumferential stress and the circumferential shear force.

[0092] Among them, the magnitude of the second principal stress is negatively correlated with the magnitude of the circumferential shear force, and the magnitude of the third principal stress is positively correlated with the magnitude of the second circumferential stress and the magnitude of the circumferential shear force. That is, the greater the circumferential shear force, the smaller the second principal stress, the smaller the circumferential shear force, and the greater the second principal stress. The greater the second circumferential stress, the greater the third principal stress, the smaller the second circumferential stress, and the smaller the third principal stress. The greater the circumferential shear force, the greater the third principal stress, the smaller the circumferential shear force, and the smaller the third principal stress.

[0093] The directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other.

[0094] Optionally, the second principal stress σ k satisfy:

[0095] The third principal stress σ j satisfy:

[0096] Step 205: Obtain rock mechanical parameters at the point to be drilled.

[0097] After determining the first principal stress, the second principal stress and the third principal stress, the computer device can also obtain the rock mechanical parameters at the point to be drilled, and the rock mechanical parameters can include uniaxial compression strength, pore pressure and overburden pressure. Optionally, the logging tool can also include a strength detector, which is used to measure the uniaxial compression strength at the point to be drilled. The pressure detector can be used to measure the overburden pressure. The driller can store the uniaxial compression strength measured by the strength detector and the overburden pressure measured by the pressure detector in the computer device, and then the computer device can obtain the pre-stored rock mechanical parameters at the point to be drilled.

[0098] Step 206: determine the triaxial compression strength at the drilling point according to the pore pressure and the difference between the maximum principal stress and the minimum principal stress.

[0099] After determining the first principal stress, the second principal stress and the third principal stress, the computer device can determine the maximum principal stress and the minimum principal stress among the first principal stress, the second principal stress and the third principal stress. And the difference between the maximum principal stress and the minimum principal stress can be determined. And after obtaining the rock mechanics parameters at the point to be drilled, the computer device can determine the triaxial compression strength at the point to be drilled according to the pore pressure in the rock mechanics parameters and the difference between the maximum principal stress and the minimum principal stress. Among them, the magnitude of the triaxial compression strength is positively correlated with the magnitude of the pore pressure, that is, the greater the pore pressure, the greater the triaxial compression strength, and the smaller the pore pressure, the smaller the triaxial compression strength.

[0100] In the embodiment of the present disclosure, the triaxial compressive strength σ at the drilling point is s Can satisfy:

[0101] Among them, the p 1 is the pore pressure, the Q 1 is the difference between the maximum principal stress and the minimum principal stress, the Q 2 is the uniaxial compression strength at the drilling point. K is the influence coefficient of the confining pressure on the strength of the rock at the drilling point when the confining pressure at the drilling point is 0. The confining pressure refers to the pressure of the rock around the drilling point on the rock at the drilling point.

[0102] Step 207: Determine the collapse pressure at the drilling point according to the pore pressure, the overburden pressure, the intermediate principal stress and the triaxial compression strength.

[0103] In the disclosed embodiment, after determining the pore pressure, overburden pressure, second principal stress and triaxial compression strength, the computer device can determine the collapse pressure at the drilling point according to the pore pressure, overburden pressure, second principal stress and triaxial compression strength. The collapse pressure is positively correlated with the intermediate principal stress, the pore pressure and the overburden pressure.

[0104] Optionally, the collapse pressure P1 may satisfy:

[0105] Among them, the p 2 is the overburden pressure, σ 1 is the intermediate principal stress. γ is a constant, for example, γ can be 1.6.

[0106] Step 208: Obtain target pressure.

[0107] After the computer device outputs the collapse pressure at the point to be drilled according to the first principal stress, the second principal stress and the third principal stress, it can also obtain the target pressure.

[0108] The target pressure P2 can meet the following requirements: Should is the internal friction angle of the rock at the point to be drilled, c is the cohesion of the rock at the point to be drilled, and σ 2 is the minimum principal stress, and the target pressure P2 is positively correlated with the minimum principal stress.

[0109] Step 209: output the difference between the target pressure and the collapse pressure.

[0110] After obtaining the target pressure, the computer device can also determine the difference between the target pressure and the collapse pressure, and can output the difference between the target pressure and the collapse pressure, which is used to indicate whether the well wall will collapse when drilling continues at the point to be drilled. Therefore, the driller can accurately judge whether the well wall will collapse when drilling at the point to be drilled based on the difference output by the computer device, thereby improving the reliability of determining whether the well wall will collapse. Among them, the difference F between the target pressure and the collapse pressure satisfies: F = P2-P1.

[0111] In the disclosed embodiment, after determining the difference between the target pressure and the collapse pressure, the computer device can also detect whether the difference between the target pressure and the collapse pressure is greater than a preset difference. If the difference between the target pressure and the collapse pressure is less than the preset difference, the computer device can issue an alarm message, which is used to indicate that the wellbore wall will collapse when drilling at the drilling point. For example, the alarm message can be "Warning: Continuing drilling here will cause the wellbore wall to collapse". The preset difference is a value pre-stored in the computer device. For example, the preset difference can be 0.

[0112] If the difference between the target pressure and the collapse pressure is less than or equal to the preset difference, the computer device can output result information, which is used to indicate that the well wall will not collapse when drilling at the point to be drilled. For example, the result information can be "You can continue drilling here". In the embodiment of the present disclosure, since the computer device can directly output alarm information or result information, so that the driller can intuitively see whether the well wall will collapse when drilling at the point to be drilled, without the need for the driller to make a judgment, the efficiency of determining whether the well wall will collapse is improved, and the user experience is better.

[0113] It should be noted that the above embodiment is described by taking the drilling personnel using the logging tool to obtain the above parameters as an example. Optionally, the logging tool can also communicate with a computer device, and the logging tool is used to send the above parameters to the computer device after measuring the above parameters. Therefore, the embodiment of the present disclosure provides a prediction system for the collapse pressure of the well wall, and the prediction system includes the computer device and the logging tool. The prediction system can automatically predict the collapse pressure, so that the prediction of the collapse pressure is more efficient and more accurate.

[0114] Optionally, after determining the above circumferential shear stress, the computer device may also determine other circumferential shear stresses, which may include the first circumferential shear force τ rθ and the second circumferential shear stress τ rz The first circumferential shear force τ rθ The direction of the second circumferential shear force is parallel to the plane where the r axis and the θ axis of the cylindrical coordinate system are located. rz Parallel to the plane where the r-axis and z-axis of the cylindrical coordinate system are located. The first circumferential shear stress τ rθ and the second axial shear stress τ rz Satisfies the following formula:

[0115]

[0116]

[0117] Figure 4 1 is a schematic diagram of a comparison between the principal stress actually measured and the principal stress determined by the method provided in the embodiment of the present application. The principal stress includes the first principal stress, the second principal stress and the third principal stress. Figure 4 As shown, the horizontal axis in the comparative schematic diagram represents the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress, and its unit is megapascal (MPa). The vertical axis in the comparative schematic diagram represents the maximum principal stress among the first principal stress, the second principal stress and the third principal stress, and its unit is MPa.

[0118] The first curve, the second curve, the third curve, the fourth curve and the fifth curve in the comparison schematic diagram are multiple first principal stresses σ determined by the method provided in the embodiment of the present application at multiple different in situ stresses, well inclination angles and well inclination azimuths. i , multiple second principal stresses σ k and multiple third principal stresses σ j The multiple measured points are multiple first principal stresses σ actually measured at the multiple different in situ stresses, well inclination angles and well inclination azimuths. i , multiple second principal stresses σ k and multiple third principal stresses σ j .

[0119] Among them, the first curve is the minimum principal stress σ 2 When the value is 0MPa, the curves obtained by fitting multiple maximum principal stresses and multiple intermediate principal stresses are shown in the figure below. Figure 4 It can be seen that a plurality of first measured points actually measured at the same in situ stress, well inclination angle and well inclination azimuth are evenly distributed around the first curve.

[0120] The second curve is the minimum principal stress σ 2 When the value is 30MPa, the curves obtained by fitting multiple maximum principal stresses and multiple intermediate principal stresses are shown in the figure below. Figure 4 It can be seen that a plurality of second measured points actually measured at the same in situ stress, well inclination angle and well inclination azimuth are evenly distributed around the second curve.

[0121] The third curve is the minimum principal stress σ 2 When the value is 30MPa, the curves obtained by fitting multiple maximum principal stresses and multiple intermediate principal stresses are shown in the figure below. Figure 4 It can be seen that a plurality of third measured points actually measured at the same in situ stress, well inclination angle and well inclination azimuth are evenly distributed around the third curve.

[0122] The fourth curve is the minimum principal stress σ 2 When the value is 30MPa, the curves obtained by fitting multiple maximum principal stresses and multiple intermediate principal stresses are shown in the figure below. Figure 4 It can be seen that a plurality of fourth measured points actually measured at the same in situ stress, well inclination angle and well inclination azimuth are evenly distributed around the fourth curve.

[0123] The fifth curve is the minimum principal stress σ 2 When the value is 30MPa, the curves obtained by fitting multiple maximum principal stresses and multiple intermediate principal stresses are shown in the figure below. Figure 4 It can be seen that a plurality of fifth measured points actually measured at the same in situ stress, well inclination angle and well inclination azimuth are evenly distributed around the fifth curve.

[0124] Since multiple measured points are evenly distributed around the multiple curves at the same in situ stress, well inclination angle and well inclination azimuth, it can be shown that the principal stress determined by the method provided in the embodiment of the present application is slightly different from the actually measured principal stress, indicating that the principal stress determined by the method provided in the embodiment of the present application has a higher accuracy.

[0125] The method provided in the embodiment of the present application is used to analyze the inclined well of the sandstone reservoir in a certain area, wherein the reservoir parameters in the area are as follows: the formation depth is 2050m, the overburden pressure is 51.57MPa, the horizontal maximum stress in the in-situ stress is 42.8MPa, the horizontal minimum stress in the in-situ stress is 36.2MPa, the pore pressure is 15.57MPa, the effective stress coefficient is 0.75, and the Poisson's ratio is 0.33.

[0126] Figure 5 This is a cloud diagram of changes in collapse pressure determined by a method provided in an embodiment of the present application. Figure 6 It is a cloud diagram of the change of collapse pressure determined by the method provided by the relevant technology. Figure 5 and Figure 6 As shown, the horizontal axis in the change cloud map represents the well inclination azimuth, and the vertical axis represents the well inclination angle. The filling color in the change cloud map changes from dark to light and then to dark in the direction of increasing vertical axis, indicating that the collapse pressure changes from small to large.

[0127] refer to Figure 5 , using the method provided in the embodiment of the present application, when the well inclination angle is greater than or equal to 0° and less than or equal to 90°, and the well inclination azimuth angle is greater than or equal to 0° and less than or equal to 90°, the determined collapse pressure is greater than or equal to 90 MPa and less than or equal to 121 MPa.

[0128] When the drilling direction of the wellbore at the point to be drilled satisfies: the well inclination angle is greater than or equal to 40° and less than or equal to 45°, and the well inclination azimuth is greater than or equal to 85° and less than or equal to 90°, the collapse pressure of the wellbore wall is small, and the wellbore wall will not collapse. The well inclination angle and well inclination azimuth are the best drilling trajectory. When the drilling direction of the wellbore at the point to be drilled satisfies: the well inclination angle is greater than or equal to 78° and less than or equal to 90°, and the well inclination azimuth is greater than or equal to 0° and less than or equal to 28°, the wellbore wall is prone to collapse.

[0129] refer to Figure 6, using the method provided by the relevant technology, without considering the intermediate principal stress to determine the collapse pressure, when the well inclination angle is greater than or equal to 0° and less than or equal to 90°, and the well inclination azimuth is greater than or equal to 0° and less than or equal to 90°, the determined collapse pressure is greater than or equal to 110MPa and less than or equal to 121MPa. It can be seen that the collapse pressure determined by the method provided by the relevant technology is too large.

[0130] When the wellbore drilling direction at the point to be drilled satisfies: the well inclination is greater than or equal to 35° and less than or equal to 45°, the azimuth is greater than or equal to 80° and less than or equal to 90°, the wellbore collapse pressure is small. When the wellbore drilling direction at the point to be drilled satisfies: the well inclination is greater than or equal to 78° and less than or equal to 90°, the azimuth is greater than or equal to 0° and less than or equal to 28°, the wellbore collapse pressure is high, and collapse is likely to occur at this time.

[0131] It should be noted that the order of the steps of the method for determining the collapse pressure of the well wall provided in the embodiment of the present application can be appropriately adjusted, and the steps can also be deleted according to the situation. For example, step 208 and step 209 can be deleted according to the situation, or if the computer device obtains the bottom hole liquid column pressure in the above step 202, only step 208 can be deleted. Or step 205 can be executed before step 201. Any technician familiar with the technical field can easily think of a change within the technical scope disclosed in this application, which should be covered within the scope of protection of this application, so it will not be repeated.

[0132] In summary, the disclosed embodiment provides a method for determining the collapse pressure of a wellbore. Since the computer device can output the collapse pressure at the point to be drilled based on the first principal stress, the second principal stress, and the third principal stress determined by the in situ stress, the well inclination angle, and the well inclination azimuth, the wellbore driller can accurately determine whether the wellbore wall will collapse when drilling at the wellbore point based on the collapse pressure, thereby effectively improving the accuracy of determining whether the wellbore wall collapses. Moreover, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the wellbore wall collapses is further improved.

[0133] Figure 7 FIG. 7 is a block diagram of a device 70 for determining the collapse pressure of a wellbore provided in an embodiment of the present disclosure. Figure 7 As shown, the device may include:

[0134] The first acquisition module 701 is used to acquire the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall.

[0135] The determination module 702 is used to determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth.

[0136] The first output module 703 is used to output the collapse pressure at the drilling point according to the first principal stress, the second principal stress and the third principal stress.

[0137] Among them, the directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other, and the magnitude of the collapse pressure is positively correlated with the magnitude of the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress.

[0138] In summary, the disclosed embodiment provides a device for determining the collapse pressure of a wellbore. Since the device can output the collapse pressure at the point to be drilled based on the first principal stress, the second principal stress, and the third principal stress determined by the in situ stress, the well inclination angle, and the well inclination azimuth, the wellbore driller can accurately determine whether the wellbore wall will collapse when drilling at the wellbore point based on the collapse pressure, thereby effectively improving the accuracy of determining whether the wellbore wall collapses. Moreover, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the wellbore wall collapses is further improved.

[0139] Optionally, the first acquisition module 701 is used to:

[0140] Obtain the rock mechanics parameters at the point to be drilled, which include uniaxial compression strength, pore pressure and overburden pressure.

[0141] The triaxial compressive strength at the drilling point is determined according to the pore pressure and the difference between the maximum principal stress and the minimum principal stress. The triaxial compressive strength is positively correlated with the pore pressure. The maximum principal stress is the principal stress with the largest value among the first principal stress, the second principal stress and the third principal stress, and the minimum principal stress is the principal stress with the smallest value among the first principal stress, the second principal stress and the third principal stress.

[0142] The collapse pressure at the drilling point is determined according to the pore pressure, overburden pressure, intermediate principal stress and triaxial compression strength, and the collapse pressure at the drilling point is output. The collapse pressure is also positively correlated with the pore pressure and the overburden pressure.

[0143] Optionally, the triaxial compressive strength σ at the point to be drilled s satisfy:

[0144] Among them, p 1 is the pore pressure, Q 1 is the difference between the maximum principal stress and the minimum principal stress, Q 2 is the uniaxial compression strength at the drilling point, and K is the influence coefficient of the confining pressure on the strength of the rock at the drilling point when the confining pressure at the drilling point is 0.

[0145] Optionally, the collapse pressure P1 satisfies: P1 = σ s +σ 1 ×f×e 1-f ,

[0146] Among them, σ s is the triaxial compressive strength, σ 1 is the intermediate principal stress, p 1 is the pore pressure, p 2 is the overburden pressure, and γ is a constant.

[0147] Optionally, the determination module 702 is used to:

[0148] According to the in situ stress, well inclination angle and well inclination azimuth, the first circumferential stress, the second circumferential stress, the third circumferential stress and the circumferential shear force at the drilling point in the cylindrical coordinate system are determined, and the plane where the polar coordinate system in the cylindrical coordinate system is located is the plane tangent to the well wall.

[0149] Determine that the first principal stress is equal to the first circumferential stress.

[0150] The second principal stress and the third principal stress are determined according to the second circumferential stress, the third circumferential stress and the circumferential shear force.

[0151] Among them, the magnitude of the second principal stress is negatively correlated with the magnitude of the circumferential shear force, and the magnitude of the third principal stress is positively correlated with the magnitudes of the second circumferential stress and the circumferential shear force.

[0152] Optionally, the second principal stress σ k satisfy:

[0153] The third principal stress σ j satisfy:

[0154] Among them, σ θ is the second circumferential stress, σ z is the third circumferential stress, τ θz is the circumferential shear force.

[0155] Optional, such as Figure 8 As shown, the device may also include:

[0156] The second acquisition module 704 is used to acquire a target pressure after outputting the collapse pressure at the drilling point according to the first principal stress, the second principal stress and the third principal stress. The target pressure is positively correlated with the minimum principal stress.

[0157] The second output module 705 is used to output the difference between the target pressure and the collapse pressure, and the difference is used to indicate whether the wellbore wall will collapse when drilling at the point to be drilled.

[0158] The target pressure P2 satisfies:

[0159] is the internal friction angle of the rock at the point to be drilled, c is the cohesion of the rock at the point to be drilled, σ 2 is the minimum principal stress.

[0160] In summary, the disclosed embodiment provides a device for determining the collapse pressure of a wellbore. Since the device can output the collapse pressure at the point to be drilled based on the first principal stress, the second principal stress, and the third principal stress determined by the in situ stress, the well inclination angle, and the well inclination azimuth, the wellbore driller can accurately determine whether the wellbore wall will collapse when drilling at the wellbore point based on the collapse pressure, thereby effectively improving the accuracy of determining whether the wellbore wall collapses. Moreover, since the intermediate principal stress is taken into account in the process of determining the collapse pressure, the accuracy of determining whether the wellbore wall collapses is further improved.

[0161] The present application provides a computer device, including: a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the above method embodiment (for example Figure 1 or Figure 2 embodiment shown).

[0162] The present application embodiment provides a computer-readable storage medium, in which instructions are stored. When the instructions are loaded and executed by a processor to implement the above method embodiment (such as Figure 1 or Figure 2 The method embodiment shown).

[0163] The present application embodiment provides a computer program product including instructions. When the computer program product is run on a computer, the computer executes the above method embodiment (for example, Figure 1 Or the embodiment shown in 2).

[0164] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the embodiments of the present application, the term "plurality" means two or more.

[0165] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for determining the collapse pressure of a wellbore, characterized in that: Applied to a computer device, the method comprises: Obtaining the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall; Determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth; outputting the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress; Wherein, the directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other, and the magnitude of the collapse pressure is positively correlated with the magnitude of the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress; Wherein, outputting the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress comprises: Obtaining rock mechanics parameters at the point to be drilled, wherein the rock mechanics parameters include uniaxial compression strength, pore pressure, and overburden pressure; Determine the triaxial compressive strength at the drilling point according to the pore pressure and the difference between the maximum principal stress and the minimum principal stress, wherein the triaxial compressive strength is positively correlated with the pore pressure, the maximum principal stress is the principal stress with the largest value among the first principal stress, the second principal stress and the third principal stress, and the minimum principal stress is the principal stress with the smallest value among the first principal stress, the second principal stress and the third principal stress; Determine the collapse pressure at the point to be drilled according to the pore pressure, the overburden pressure, the intermediate principal stress and the triaxial compression strength, and output the collapse pressure at the point to be drilled, wherein the collapse pressure is positively correlated with the pore pressure and the overburden pressure; the intermediate principal stress is the principal stress among the first principal stress, the second principal stress and the third principal stress except the maximum principal stress and the minimum principal stress; The triaxial compression strength at the drilling point satisfy: ; Among them, the p 1 is the pore pressure, Q 1 is the difference between the maximum principal stress and the minimum principal stress, Q 2 is the uniaxial compression strength at the point to be drilled, and K is the influence coefficient of the confining pressure on the strength of the rock at the point to be drilled when the confining pressure at the point to be drilled is 0; The collapse pressure P1 satisfies: ; Among them, the is the triaxial compressive strength, is the intermediate principal stress, p 1 is the pore pressure, p 2 is the overburden pressure, γ is constant; After outputting the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress, the method further includes: Obtain a target pressure, wherein the target pressure is positively correlated with the minimum principal stress; the target pressure P 2. Satisfy: ; Said is the internal friction angle of the rock at the drilling point, c is the cohesive force of the rock at the drilling point, is the minimum principal stress; The difference between the target pressure and the collapse pressure is output, and the difference is used to indicate whether the well wall will collapse when drilling at the point to be drilled.

2. The method according to claim 1, characterized in that: Determining the first principal stress, the second principal stress, and the third principal stress at the drilling point according to the in situ stress, the well inclination angle, and the well inclination azimuth includes: Determine the first circumferential stress, the second circumferential stress, and the third circumferential stress at the drilling point in a cylindrical coordinate system according to the in situ stress, the well inclination angle, and the well inclination azimuth, wherein the plane where the polar coordinate system in the cylindrical coordinate system is located is a plane tangent to the well wall; determining that the first principal stress is equal to the first circumferential stress; determining the second principal stress and the third principal stress according to the second circumferential stress, the third circumferential stress and the circumferential shear force; The magnitude of the second principal stress is negatively correlated with the magnitude of the circumferential shear force, and the magnitude of the third principal stress is positively correlated with the magnitudes of the second circumferential stress and the magnitudes of the circumferential shear force.

3. The method according to claim 2, characterized in that The second principal stress satisfy: ; The third principal stress satisfy: ; Among them, the is the second circumferential stress, is the third circumferential stress, is the circumferential shear force.

4. A device for determining the collapse pressure of a well wall, characterized in that: The device comprises: A first acquisition module is used to acquire the in-situ stress of the well wall and the well inclination angle and well inclination azimuth at the point to be drilled in the well wall; A determination module, used to determine the first principal stress, the second principal stress and the third principal stress at the drilling point according to the in situ stress, the well inclination angle and the well inclination azimuth; A first output module, configured to output the collapse pressure at the to-be-drilled point according to the first principal stress, the second principal stress and the third principal stress; Wherein, the directions of the first principal stress, the second principal stress and the third principal stress are perpendicular to each other, and the magnitude of the collapse pressure is positively correlated with the magnitude of the intermediate principal stress among the first principal stress, the second principal stress and the third principal stress; Wherein, the first output module is used for: Obtaining rock mechanics parameters at the point to be drilled, wherein the rock mechanics parameters include uniaxial compression strength, pore pressure, and overburden pressure; Determine the triaxial compressive strength at the drilling point according to the pore pressure and the difference between the maximum principal stress and the minimum principal stress, wherein the triaxial compressive strength is positively correlated with the pore pressure, the maximum principal stress is the principal stress with the largest value among the first principal stress, the second principal stress and the third principal stress, and the minimum principal stress is the principal stress with the smallest value among the first principal stress, the second principal stress and the third principal stress; Determine the collapse pressure at the point to be drilled according to the pore pressure, the overburden pressure, the intermediate principal stress and the triaxial compression strength, and output the collapse pressure at the point to be drilled, wherein the collapse pressure is positively correlated with the pore pressure and the overburden pressure; the intermediate principal stress is the principal stress among the first principal stress, the second principal stress and the third principal stress except the maximum principal stress and the minimum principal stress; The triaxial compression strength at the drilling point satisfy: ; Among them, the p 1 is the pore pressure, Q 1 is the difference between the maximum principal stress and the minimum principal stress, Q 2 is the uniaxial compression strength at the point to be drilled, and K is the influence coefficient of the confining pressure on the strength of the rock at the point to be drilled when the confining pressure at the point to be drilled is 0; The collapse pressure P1 satisfies: ; Among them, the is the triaxial compressive strength, is the intermediate principal stress, p 1 is the pore pressure, p 2 is the overburden pressure, γ is constant; The device also includes: The second acquisition module is used to obtain a target pressure after outputting the collapse pressure at the drilling point according to the first principal stress, the second principal stress and the third principal stress, wherein the target pressure is positively correlated with the minimum principal stress; the target pressure P 2. Satisfy: ; Said is the internal friction angle of the rock at the drilling point, c is the cohesive force of the rock at the drilling point, is the minimum principal stress; The second output module is used to output the difference between the target pressure and the collapse pressure, wherein the difference is used to indicate whether the wellbore wall will collapse when drilling at the point to be drilled.

5. A computer device, characterized in that: include: A memory, a processor and a computer program stored in the memory, wherein when the processor executes the computer program, the method for determining the collapse pressure of the well wall as described in any one of claims 1 to 3 is implemented.

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