Method and device for obtaining borehole collapse pressure based on rock integrity factor

Abstract

The application relates to the technical field of oil exploitation and processing, and is a well wall collapse pressure acquisition method and device based on a rock integrity coefficient, which comprises the following steps: calculating a cohesion force correction value by using the rock integrity coefficient; calculating an internal friction angle correction value by using the cohesion force correction value; establishing a well wall collapse pressure calculation model by using the cohesion force correction value, the internal friction angle correction value and a pressure difference generated by drilling fluid seepage; and calculating the well wall collapse pressure based on the well wall collapse pressure calculation model. When the well wall collapse pressure is calculated, the changes of the cohesion force and the internal friction angle caused by the stratum breaking degree and the stratum pore pressure rise caused by the drilling fluid seepage are considered as multiple influence factors, so that the accuracy of the well wall collapse pressure predicted according to the application is improved.

Description

Technical Field

[0001] This invention relates to the field of oil extraction and processing technology, and is a method and apparatus for obtaining wellbore collapse pressure based on rock integrity coefficient. Background Technology

[0002] In oil drilling, accurately predicting wellbore collapse pressure is crucial for ensuring drilling safety. Existing methods for calculating collapse pressure mostly rely on empirical formulas or simplified models, which often fail to accurately reflect the actual conditions under complex geological conditions.

[0003] Patent application CN120007229A discloses a new method for calculating wellbore collapse pressure in fractured shale formations, including: Step 1, preparing experimental rock samples and conducting acoustic property tests on bedrock and fractured rock samples, as well as mechanical tests on the rock samples; Step 2, calculating the rock integrity coefficient K. υ Step 1: Geological strength index GSI, rock mass disturbance coefficient D, and lithological index mi; Step 2: Establish the Hoek-Brown strength criterion based on acoustic evaluation of fractured formations; Step 3: Calculate the principal stress expressions for the wellbore of deviated and horizontal wells; Step 4: Establish a calculation model for wellbore collapse pressure in fractured oil shale formations.

[0004] Patent application CN119801502A discloses a method for predicting shale oil wellbore collapse pressure. The steps are as follows: obtaining the composition, structure, and physicochemical properties of the shale oil reservoir; conducting immersion-NMR-sonic-triaxial stress measurement experiments with different drilling fluid systems; constructing equations for heterogeneous water absorption and strength degradation of shale oil reservoir rocks; establishing geostress and pore pressure profiles; converting far-field stress to wellbore and bedding coordinate systems; calculating the wellbore stress field generated by water absorption in the surrounding rock; simulating and calculating the temperature field distribution of the rock and calculating the thermal stress value; superimposing and calculating the wellbore stress value under the coupling of force, chemistry, heat, and physiology; constructing the discrimination function and conditions for shear failure of the surrounding rock matrix and weak surfaces; constructing an iterative algorithm for numerical simulation of shale oil reservoir collapse pressure; determining the control factors and control mechanisms of formation collapse pressure density; and reducing the risk of shale oil wellbore collapse through optimization.

[0005] Patent application CN119333120A discloses a method and related equipment for calculating wellbore collapse pressure of different sizes, belonging to the technical field of drilling engineering. The method includes the following steps: calculating the geostress characteristic parameters of the target formation based on logging parameters; establishing a wellbore collapse pressure calculation model for the target formation based on the geostress characteristic parameters; introducing a size effect into the wellbore collapse pressure calculation model to obtain a mathematical model of the wellbore collapse pressure of the target formation; and substituting the geostress characteristic parameters into the wellbore collapse pressure mathematical model to obtain the equivalent density of the collapse pressure of wellbore walls of different sizes.

[0006] The existing literature does not consider the impact of changes in physical properties after rock fracturing, pressure changes after drilling fluid seepage, and drilling conditions on wellbore collapse pressure. Summary of the Invention

[0007] This invention provides a method and apparatus for obtaining wellbore collapse pressure based on rock integrity coefficient, which overcomes the shortcomings of the prior art. It considers the influence of changes in physical properties after rock fracturing and pressure changes after drilling fluid seepage on wellbore collapse pressure, thereby improving the accuracy of wellbore collapse pressure calculation.

[0008] One of the technical solutions of this invention is achieved through the following measures: a method for obtaining wellbore collapse pressure based on rock integrity coefficient, comprising:

[0009] Calculate the cohesion correction value using the rock integrity coefficient;

[0010] Calculate the internal friction angle correction value using the cohesive force correction value;

[0011] A wellbore collapse pressure calculation model was established using cohesion correction values, internal friction angle correction values, and pressure differentials generated by drilling fluid seepage.

[0012] Wellbore collapse pressure is calculated based on a wellbore collapse pressure calculation model.

[0013] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0014] The aforementioned rock integrity coefficient is calculated based on the P-wave sonic transit time or seismic layer velocity.

[0015] Kv=(AC wr / AC pr ) 2 Or, Kv = (V pr / V wr ) 2

[0016] In the formula, For the longitudinal wave time difference of fractured rock, ; For the longitudinal wave sonic transit time of intact rock, ; For the velocity of the fractured rock seismic layer, ; For the velocity of intact rock seismic layers, .

[0017] The above calculation of cohesion correction values ​​using rock integrity coefficients specifically includes: for steep, large-scale strata with the same lithology but different degrees of fracturing in front of mountains, the cohesion correction value is calculated using the following formula.

[0018] C 破碎 =0.0721×C 完整 e 2.6296Kv

[0019] In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

[0020] The above calculation of the internal friction angle correction value using the cohesion correction value specifically includes: calculating the internal friction angle correction value according to the following formula.

[0021]

[0022] In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

[0023] The calculation model for wellbore collapse pressure is as follows:

[0024]

[0025] In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction coefficient, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

[0026] The second technical solution of the present invention is achieved through the following measures: an apparatus for implementing a method for obtaining wellbore collapse pressure based on rock integrity coefficient, comprising:

[0027] Cohesion correction value calculation module: Calculates the cohesion correction value using the rock integrity coefficient;

[0028] Internal friction angle correction value calculation module: Calculates the internal friction angle correction value using the cohesion correction value;

[0029] Model building module: Establish a wellbore collapse pressure calculation model using cohesion correction value, internal friction angle correction value and pressure difference generated by drilling fluid seepage;

[0030] Wellbore collapse pressure calculation module: Calculates wellbore collapse pressure based on the wellbore collapse pressure calculation model.

[0031] The following are further optimizations and / or improvements to the second technical solution of the above invention:

[0032] The aforementioned cohesion correction value calculation module includes a cohesion correction value calculation unit. This unit calculates the cohesion correction value using the following formula for steep, complex strata with the same lithology but different degrees of fracturing in front of a mountain.

[0033] C 破碎 =0.0721×C 完整 e 2.6296Kv

[0034] In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

[0035] The aforementioned internal friction angle correction value calculation module includes an internal friction angle correction value calculation unit, which calculates the internal friction angle correction value.

[0036] In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

[0037] The above model building module includes a model building unit. The model building unit's wellbore collapse pressure calculation model is as follows:

[0038]

[0039] In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction coefficient, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

[0040] The present invention has the following beneficial effects:

[0041] 1) Improved calculation accuracy: When calculating wellbore collapse pressure, this invention considers various influencing factors such as the cohesion caused by the degree of formation fracturing, the change in internal friction angle, and the increase in formation pore pressure caused by drilling fluid seepage. Therefore, the accuracy of the wellbore collapse pressure predicted by this invention is improved.

[0042] 2) Wide applicability: It is applicable to drilling projects under different geological conditions, no longer limited to intact lithological formations, and is also applicable to fractured formations.

[0043] 3) Easy to operate: The required data can be easily obtained through sonic logging technology, simplifying the calculation process.

[0044] 4) Pre-drilling prediction is possible: By using the wellbore collapse pressure calculation model and combining it with seismic layer velocity, pre-drilling prediction analysis of collapse pressure can be carried out to ensure drilling safety. Attached Figure Description

[0045] Appendix Figure 1 This is a technical roadmap for the present invention.

[0046] Appendix Figure 2 This is a regression analysis of the actual rock cohesion and rock integrity coefficient.

[0047] Appendix Figure 3 Comparison chart before and after collapse pressure correction.

[0048] Figure 3 In this context, cohesion (correction) refers to the cohesion correction value; internal friction angle (correction) refers to the internal friction angle correction value. Detailed Implementation

[0049] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0050] The present invention will be further described below with reference to embodiments:

[0051] Example 1: As Figure 1 As shown, a method for obtaining wellbore collapse pressure based on rock integrity coefficient includes:

[0052] Calculate the cohesion correction value using the rock integrity coefficient;

[0053] Calculate the internal friction angle correction value using the cohesive force correction value;

[0054] A wellbore collapse pressure calculation model was established using cohesion correction values, internal friction angle correction values, and pressure differentials generated by drilling fluid seepage.

[0055] Wellbore collapse pressure is calculated based on a wellbore collapse pressure calculation model.

[0056] Example 2: As an optimization of the above example, the rock integrity coefficient is calculated based on the P-wave sonic transit time or seismic layer velocity.

[0057] Kv=(AC wr / AC pr ) 2 Or, Kv = (V pr / V wr ) 2

[0058] In the formula, For the longitudinal wave time difference of fractured rock, ; For the longitudinal wave sonic transit time of intact rock, ; For the velocity of the fractured rock seismic layer, ; For the velocity of intact rock seismic layers, .

[0059] Example 3: As an optimization of the above examples, the cohesion correction value is calculated using the rock integrity coefficient. Specifically, for steep, large-scale strata with the same lithology but different degrees of fracture in front of a mountain, the cohesion correction value is calculated using the following formula.

[0060] C 破碎 =0.0721×C 完整 e 2.6296Kv

[0061] In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

[0062] Example 4: As an optimization of the above embodiment, the internal friction angle correction value is calculated using the cohesion correction value, specifically including: calculating the internal friction angle correction value according to the following formula.

[0063]

[0064] In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

[0065] Example 5: As an optimization of the above examples, the wellbore collapse pressure calculation model is as follows:

[0066]

[0067] In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction coefficient, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa;h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

[0068] Example 6: An apparatus for implementing a method for obtaining wellbore collapse pressure based on rock integrity coefficient, comprising:

[0069] Cohesion correction value calculation module: Calculates the cohesion correction value using the rock integrity coefficient;

[0070] Internal friction angle correction value calculation module: Calculates the internal friction angle correction value using the cohesion correction value;

[0071] Model building module: Establish a wellbore collapse pressure calculation model using cohesion correction value, internal friction angle correction value and pressure difference generated by drilling fluid seepage;

[0072] Wellbore collapse pressure calculation module: Calculates wellbore collapse pressure based on the wellbore collapse pressure calculation model.

[0073] Example 7: As an optimization of Example 6 above, the cohesion correction value calculation module includes a cohesion correction value calculation unit. The cohesion correction value calculation unit calculates the cohesion correction value according to the following formula for steep, complex strata with the same lithology but different degrees of fracturing in front of a mountain.

[0074] C 破碎 =0.0721×C 完整 e 2.6296Kv

[0075] In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

[0076] Example 8: As an optimization of Example 6 above, the internal friction angle correction value calculation module includes an internal friction angle correction value calculation unit. The internal friction angle correction value calculation unit calculates the internal friction angle correction value according to the following formula:

[0077]

[0078] In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

[0079] The traditional formula for calculating collapse pressure is as follows:

[0080]

[0081] In the formula, P m1 σ is the collapse pressure, MPa; η is the stress nonlinearity correction factor, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa; h2 θ is the minimum principal stress in MPa; C is the cohesion in MPa; θ is the angle of internal friction in °; α is the biot coefficient, dimensionless; P p , Formation pressure, MPa.

[0082] As can be seen from the traditional formula for calculating collapse pressure: a larger stress difference (i.e., σ) h1 -σ h2 Rock strength decreases (i.e., cohesion), formation pore pressure (i.e., formation pressure P) p An increase in any of these factors will lead to an increase in collapse pressure. In fractured formations, the cohesion decreases with the degree of fracture, and drilling fluid infiltration increases formation pore pressure. Previous calculations of collapse pressure often neglected the effects of changes in cohesion and internal friction angle caused by formation fracture, as well as the increase in formation pore pressure due to drilling fluid seepage. Therefore, this paper modifies the traditional collapse pressure calculation formula based on cohesion, internal friction angle, and pressure difference generated by drilling fluid seepage, using a modified rock integrity coefficient, to obtain a collapse pressure calculation model, as shown in Example 9.

[0083] Example 9: As an optimization of Example 6 above, the model building module includes a model building unit. The model building unit's wellbore collapse pressure calculation model is as follows:

[0084]

[0085] In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction coefficient, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless, typically taken as 1; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless, typically chosen as 0.25; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

[0086] This invention establishes a wellbore collapse pressure calculation model based on the correction of cohesion and internal friction angle by the rock integrity coefficient and the pressure difference generated by drilling fluid seepage, thereby improving the applicability and accuracy of the model.

[0087] Verification and Application:

[0088] A well is located on the southern edge of a basin (the strata of which are steep and complex sets of strata with the same lithology but different degrees of fracture). The well encountered multiple faults, and the strata were steep and fractured. The well was stuck multiple times during the drilling process.

[0089] The wellbore collapse pressure acquisition method based on rock integrity coefficient described in this invention is applied to the wellbore collapse pressure calculation of a certain well, and includes the following steps:

[0090] Step 1, collect data;

[0091] Acquire formation P-wave sonic transit time data using sonic logging technology; if no P-wave sonic transit time data is available, collect seismic layer velocities.

[0092] Step 2: Calculate the rock integrity factor;

[0093] The rock integrity coefficient is calculated using the following formula:

[0094] Kv=(AC wr / AC pr ) 2 Or, Kv = (V pr / V wr ) 2

[0095] In the formula, For the longitudinal wave time difference of fractured rock, ; For the longitudinal wave sonic transit time of intact rock, ; For the velocity of the fractured rock seismic layer, ; For the velocity of intact rock seismic layers, .

[0096] The rock integrity coefficient reflects the degree of development of cracks and pores in a rock.

[0097] Step 3: Calculate the cohesion correction value using the rock integrity coefficient;

[0098] Calculate the cohesion correction value using the following formula:

[0099] C 破碎 =0.0721×C 完整 e 2.6296Kv

[0100] In the formula, C破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

[0101] The cohesion of intact rock is the cohesion value when the rock integrity coefficient Kv of the stratum equals 1. The cohesion value obtained by calculating Kv equal to 1 according to the rock cohesion formula is the intact rock cohesion of the current stratum.

[0102]

[0103] In the formula, C 完整 The cohesion of intact rock, expressed in MPa, represents the rock's ability to resist shear failure.

[0104] A is an empirical coefficient, a dimensionless constant whose value needs to be determined by fitting and regressing experimental data (such as actual rock cohesion measured by triaxial rock tests) with the calculated value of the intact rock cohesion formula. Different studies or regions may have different recommended values.

[0105] μ d This is the dynamic Poisson's ratio. It is a dimensionless quantity representing the Poisson's ratio of a rock under dynamic conditions (such as sound wave propagation). It is typically calculated from the P-wave velocity (Vp) and S-wave velocity (Vs): μ d =(Vp²-2Vs²) / [2(Vp²-Vs²)].

[0106] ρ is the bulk density, which represents the mass per unit volume of rock. The unit is usually grams per cubic centimeter (g / cm³) or kilograms per cubic meter (kg / m³), and it can be obtained through density logging.

[0107] V cl The clay content represents the volume percentage of clay minerals or argillaceous components in a rock. It is a dimensionless quantity, ranging from 0 to 1. It can be calculated from well logging curves such as natural gamma ray and neutron density.

[0108] The exponent term e in the formula for calculating the cohesive correction value 2.6296Kv Obtained using the following method:

[0109] Regression analysis was performed on the actual rock cohesion (y) measured by the triaxial rock test and the rock integrity coefficient (x) (see...). Figure 2 The fitting formula is obtained as: y = 2.5317e 2.6296x R 2 =0.8597.

[0110] Step 4: Calculate the internal friction angle correction value using the cohesion correction value;

[0111] The correction value for the internal friction angle is calculated using the following formula:

[0112]

[0113] In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

[0114] Step 5: Establish a wellbore collapse pressure calculation model using the cohesion correction value, the internal friction angle correction value, and the pressure difference generated by drilling fluid seepage. Calculate the wellbore collapse pressure based on this model. The wellbore collapse pressure calculation model is as follows:

[0115]

[0116] In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction coefficient, typically taken as 1; h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

[0117] Calculate the collapse pressure coefficient using the following formula P ’ m :

[0118] P ’ m =100×P m2 / H

[0119] In the formula ，P ’ m P is the collapse pressure coefficient, dimensionless; m2 H is the collapse pressure, MPa; H is the well depth, m.

[0120] When P m2 P is selected m At that time, the calculated collapse pressure coefficient is a corrected value for the collapse pressure coefficient, and is consistent with... Figure 3 The collapse pressure coefficient (corrected) shown in the figure is consistent with that when P m2 P is selected m1 At that time, the calculated collapse pressure coefficient is the traditional collapse pressure coefficient, which is different from... Figure 3The collapse pressure coefficient shown in the figure is consistent.

[0121] The cohesion correction value, internal friction angle correction value, and collapse pressure coefficient correction value calculated by the method described in this invention are compared with the traditional cohesion, internal friction angle, and collapse pressure coefficient values. Figure 3 .

[0122] Depend on Figure 3 It can be seen that the cohesion correction value calculated based on the rock integrity coefficient is significantly smaller than that before the correction; the internal friction angle also changes significantly before and after the correction; from the calculation results, the collapse pressure coefficient calculated by the traditional collapse pressure model is significantly inconsistent with the actual drilling situation, while the collapse pressure coefficient calculated by the wellbore collapse pressure calculation model of this invention has good consistency with the drilling fluid density and wellbore enlargement.

[0123] This invention calculates the rock integrity coefficient using acoustic transit time (or seismic layer velocity) and considers various influencing factors such as changes in cohesion and internal friction angle caused by formation fracturing and formation pore pressure increase caused by drilling fluid seepage. It also revises the wellbore collapse pressure calculation model, improving the accuracy and applicability of the calculation, which is of great significance for optimizing drilling design and ensuring drilling safety.

[0124] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for obtaining wellbore collapse pressure based on rock integrity coefficient, characterized in that, include: Calculate the cohesion correction value using the rock integrity coefficient; Calculate the internal friction angle correction value using the cohesive force correction value; A wellbore collapse pressure calculation model was established using cohesion correction values, internal friction angle correction values, and pressure differentials generated by drilling fluid seepage. Calculate wellbore collapse pressure based on a wellbore collapse pressure calculation model; The cohesion correction value is calculated using the rock integrity coefficient. Specifically, for steep, complex strata with the same lithology but different degrees of fracturing in front of a mountain, the cohesion correction value is calculated using the following formula. C 破碎 =0.0721×C 完整 And 2.6296Kv In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force within intact rock, MPa; The calculation of the internal friction angle correction value using the cohesion correction value specifically includes: calculating the internal friction angle correction value using the following formula. In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive strength correction value, in MPa; The wellbore collapse pressure calculation model is as follows: In the formula, P m σ is the wellbore collapse pressure, MPa; η is the stress nonlinearity correction factor; h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p ρ is the formation pressure, MPa; α is the biot coefficient, dimensionless; Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

2. An apparatus for implementing the wellbore collapse pressure acquisition method based on rock integrity coefficient as described in claim 1, characterized in that, include: Cohesion correction value calculation module: Calculates the cohesion correction value using the rock integrity coefficient; Internal friction angle correction value calculation module: Calculates the internal friction angle correction value using the cohesion correction value; Model building module: Establish a wellbore collapse pressure calculation model using cohesion correction value, internal friction angle correction value and pressure difference generated by drilling fluid seepage; Wellbore collapse pressure calculation module: Calculates wellbore collapse pressure based on the wellbore collapse pressure calculation model.

3. The apparatus according to claim 2, characterized in that, The cohesion correction value calculation module includes a cohesion correction value calculation unit. This unit calculates the cohesion correction value using the following formula for steep, complex strata with the same lithology but varying degrees of fracture in front of a mountain. C 破碎 =0.0721×C 完整 And 2.6296Kv In the formula, C 破碎 Kv is the cohesion correction value, MPa; Kv is the rock integrity coefficient; C 完整 The cohesive force of intact rock is MPa.

4. The apparatus according to claim 2 or 3, characterized in that, The internal friction angle correction value calculation module includes an internal friction angle correction value calculation unit, which calculates the internal friction angle correction value using the following formula: In the formula, θ1 is the correction value for the internal friction angle, in °; C 破碎 This is the cohesive correction value, in MPa.

5. The apparatus according to claim 2 or 3, characterized in that, The model building module includes a model building unit. The model building unit's wellbore collapse pressure calculation model is as follows: In the formula, P m The pressure at which the wellbore collapses, in MPa; η is the stress nonlinearity correction coefficient; σ h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p α represents the formation pressure, MPa; α is the biot coefficient, dimensionless. Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

6. The apparatus according to claim 4, characterized in that, The model building module includes a model building unit. The model building unit's wellbore collapse pressure calculation model is as follows: In the formula, P m The pressure at which the wellbore collapses, in MPa; η is the stress nonlinearity correction coefficient; σ h1 The maximum horizontal principal stress is σ, MPa; h2 The minimum principal stress is σ_0.05 MPa; C 破碎 θ1 is the cohesive force correction value, MPa; θ1 is the internal friction angle correction value, °; P p α represents the formation pressure, MPa; α is the biot coefficient, dimensionless. Δp is the pressure difference, MPa; P_C is the drilling fluid permeability coefficient, 0 to 1, dimensionless; ρ m Density of drilling fluid, g / cm³ 3 H represents the well depth, in meters (m).

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