Stratum collapse pressure measuring method combining seismic wave velocity and fault effect

Abstract

The application relates to the technical field of oil reservoir engineering, and is a stratum collapse pressure measuring and calculating method and device combining seismic wave velocity and fault effect, the method comprising the following steps: obtaining the depth pressure and the ratio of transverse wave velocity to longitudinal wave velocity of a target drilling well; establishing a collapse pressure calculation formula according to the relationship among the collapse pressure, the depth pressure and the structural influence; and measuring and calculating the stratum collapse pressure according to the depth pressure, the ratio of transverse wave velocity to longitudinal wave velocity and the collapse pressure calculation formula. The application deeply excavates the petrophysical characteristics of seismic wave velocity reaction, expresses the stratum stress balance state by using the fault activity effect, replaces the complex and difficult-to-measure rock elastic parameters in the traditional Mohr-Coulomb criterion by the ratio of transverse wave velocity to longitudinal wave velocity and the fault effect parameter, greatly simplifies the calculation process, significantly reduces the parameter acquisition difficulty, and has multiple advantages of simple operation, strong timeliness, high calculation efficiency and high accuracy, thereby providing an innovative solution for the rapid and accurate measurement of the stratum collapse pressure in the drilling engineering.

Description

Technical Field

[0001] This invention relates to the field of reservoir engineering technology, and is a method and apparatus for calculating formation collapse pressure that combines seismic wave velocity and fault effect. Background Technology

[0002] In underground engineering construction, accidents such as ground collapse and well leakage seriously threaten the safety and progress of the project. Accurately calculating ground collapse pressure and precisely determining the potential collapse location are crucial for preventing such accidents. Traditional methods for calculating ground collapse pressure are mainly based on the Mohr-Coulomb criterion, which requires obtaining multiple parameters such as the rock's elastic modulus, Poisson's ratio, cohesion, and internal friction angle, as well as the magnitude and direction of geostress. Obtaining these parameters from the laboratory requires simulating real geological environments (such as high temperature, high pressure, and complex fluid environments), resulting in high experimental costs and low time efficiency. Calculations using formulas involve multiple different formulas, and the calculation process is cumbersome and involves a large amount of data processing. The calculation of each parameter requires complex formula derivation and extensive data processing, which not only consumes significant manpower and time but is also prone to human error. Furthermore, because the parameters are interrelated and mutually influential, an error in one parameter may be amplified in subsequent calculations, ultimately leading to a significant deviation between the calculated collapse pressure and the actual situation.

[0003] In recent years, research on calculating formation collapse pressure using seismic velocities has deepened. Existing technologies mainly fall into two categories: First, by comparing the seismic layer velocity similarity between the well to be drilled and the well already drilled, adjacent wells with similar structural characteristics are selected. Rock elastic parameters are calculated using known data from the adjacent wells, and then the Mohr-Coulomb criterion is used to calculate the collapse pressure of the adjacent wells. Finally, the collapse pressure of the well to be drilled is predicted based on the layer velocity similarity. Second, by inverting shear wave velocity, P-wave velocity, and density volume using pre-stack seismic data, elastic parameters such as Poisson's ratio, Young's modulus, and internal friction angle are further derived through formulas. The collapse pressure calculation also relies on the Mohr-Coulomb criterion.

[0004] Chinese patent document CN1588127A discloses a method for predicting collapse pressure and rupture pressure before drilling using seismic layer velocity, comprising the following steps: 1) performing data correlation analysis on the seismic layer velocities of the well to be drilled and multiple adjacent drilled wells, and identifying drilled wells with a correlation coefficient greater than 0.75 as drilled wells with similar structures to be drilled; 2) using logging data sequences such as sonic transit time, natural gamma, and density, dividing the entire section of the drilled well into layers, and calculating the average sonic velocity, natural gamma, and formation density of each layer to characterize a certain thickness and similar lithology; 3) using the average sonic velocity, natural gamma, and formation density of each layer to determine the collapse pressure and rupture pressure of the drilled well; 4) establishing a logging model based on the collapse pressure and rupture pressure of the drilled well and the logging layer velocity; 5) establishing a pre-drilling prediction model for the layer velocity of the drilled well; 6) substituting the seismic layer velocity of the well to be drilled into the model in step 5) to obtain the collapse pressure and rupture pressure of the well to be drilled.

[0005] Chinese patent document CN114429017A discloses a method, storage medium, and computer equipment for predicting formation collapse pressure. The method includes: obtaining the clay content, wave impedance, elastic parameters, and fracture rock physical parameters of a target reservoir through inversion based on seismic data; determining the compressive strength and bulk modulus of the target reservoir; determining the cohesion of the target reservoir based on its compressive strength and bulk modulus; determining the overlying strata pressure and hydrostatic pressure of the target reservoir based on its density; determining the formation pressure of the target reservoir based on a formation pressure prediction model; constructing a geostress prediction model based on Hooke's law; determining the normal compliance of the target reservoir; determining the maximum and minimum horizontal geostress of the target reservoir based on the geostress prediction model; and determining the formation collapse pressure of the target reservoir using a collapse pressure prediction model based on the Mohr-Coulomb criterion. This invention can accurately predict formation collapse pressure, providing a basis for drilling operations and wellbore stability analysis.

[0006] Although these methods incorporate seismic velocity into the calculation of collapse pressure and improve the accuracy to some extent, they still have not escaped the inherent limitations of the Mohr-Coulomb criterion—the parameter acquisition process is cumbersome, involving the complex determination and calculation of multiple rock mechanics parameters, and the data processing is large and time-consuming, resulting in low computational efficiency. Summary of the Invention

[0007] This invention provides a method for calculating stratum collapse pressure by combining seismic wave velocity and fault effect, which overcomes the shortcomings of the existing technology and can effectively solve the problems of large data processing volume, long time consumption and low calculation efficiency of the existing stratum collapse pressure calculation method.

[0008] One of the technical solutions of this invention is achieved through the following measures: a method for calculating stratum collapse pressure combining seismic wave velocity and fault effect, comprising the following steps:

[0009] Obtain the depth pressure and transverse / longitudinal wave velocity ratio of the target well.

[0010] A formula for calculating collapse pressure is established based on the relationship between collapse pressure, depth pressure, and tectonic influence.

[0011] The formation collapse pressure is calculated based on the formulas for depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure.

[0012] The formula for calculating the collapse pressure is:

[0013]

[0014] In the formula, P c The collapse pressure is expressed in MPa. P z For depth pressure, MPa; The ratio of transverse to longitudinal wave velocities is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa. T To construct the correction value, MPa.

[0015] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0016] The aforementioned methods for obtaining the depth pressure and transverse / longitudinal wave velocity ratio of the target well include:

[0017] Formation density was obtained by combining well logging data with pre-stack seismic gather inversion. , transverse wave V s longitudinal waves V p ;

[0018] by transverse waves V s and longitudinal waves V p The transverse and longitudinal wave velocities were calculated.

[0019] The depth pressure is calculated using the following formula.

[0020]

[0021] In the formula, P z For depth pressure, MPa; Formation density, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H The depth of the well is in meters (m).

[0022] The above-mentioned formula for calculating collapse pressure, based on the relationship between collapse pressure, depth pressure, and tectonic influences, includes:

[0023] The regional formation coefficient is determined based on the collapse pressure measured in the drilling experiment and the collapse pressure monitored while drilling.

[0024] Based on the ratio of transverse and longitudinal wave velocities in the gently sloping formation with minimal tectonic disturbance in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling, the rock deformation threshold value is determined.

[0025] The structural correction value is determined based on the formation uplift or compression thickness and the collapse pressure data monitored during drilling in adjacent wells;

[0026] A formula for calculating collapse pressure is established based on depth pressure, the ratio of transverse to longitudinal wave velocities, tectonic correction values, regional stratigraphic coefficients, and rock deformation threshold values.

[0027] The above-mentioned determination of the regional formation coefficient based on the collapse pressure measured in drilling experiments and the collapse pressure monitored while drilling includes: calculating the regional formation coefficient using the following formula.

[0028]

[0029] In the formula, R This is a regional stratigraphic coefficient, dimensionless. P ct The collapse pressure, measured during drilling, is MPa. P cs The collapse pressure, measured in MPa, is the pressure obtained from the drilling experiment.

[0030] The rock deformation threshold value is determined based on the transverse and longitudinal wave velocity ratio of the gently sloping formation with minimal tectonic disturbance in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling. This includes:

[0031] In the area where the target well is located, select gentle strata with minimal tectonic disturbance as the data acquisition strata;

[0032] The data acquisition formation's transverse and longitudinal wave velocity ratios, as well as the collapse pressure and depth pressure monitored during drilling, were obtained.

[0033] The rock deformation threshold value in the target drilling area is obtained by back-calculation using the following formula;

[0034]

[0035] In the formula, The collapse pressure (MPa) of the formation monitored during drilling for data acquisition. The depth pressure of the formation used for data acquisition is measured in MPa. The ratio of transverse and longitudinal wave velocities in the data acquisition strata is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c Rock deformation threshold, MPa.

[0036] The above-mentioned structural correction values ​​are determined based on the formation uplift or compression thickness and the collapse pressure data monitored while drilling in adjacent wells, including:

[0037] The construction correction value is calculated using the following formula:

[0038]

[0039] In the formula, T To construct the correction value, MPa; k The pressure reduction or enhancement coefficient for the fault is expressed in MPa / m. L The thickness of the strata due to uplift or compression is measured in meters (m).

[0040] The above-mentioned fault decompression or pressurization coefficient k Determine by following these steps:

[0041] Obtain the collapse pressure data while drilling from adjacent wells in the region with similar structures to the target well, and calculate the structural correction value for the adjacent wells using the following formula. T i ,

[0042]

[0043] In the formula, T i For the first i Structural correction value for adjacent well No. , MPa; P ci For the first i The collapse pressure monitored during drilling of the adjacent well, in MPa; For the first i Formation density of adjacent well #, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H i For the first i The depth of the adjacent well, in meters; For the first i The ratio of transverse and longitudinal wave velocities of adjacent wells is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa.

[0044] The first was obtained through seismic profile measurements. i Formation uplift or compression thickness of adjacent well No. L i;

[0045] Based on the structural correction value of adjacent wells T i Formation uplift or compression thickness with adjacent wells L i The fault decompression or pressurization coefficient is obtained according to the following formula. k :

[0046]

[0047] In the formula, d i For the first i The distance from the adjacent well to the target well, in meters; The weighting factor is dimensionless. T i For the first i Structural correction value for adjacent well No. 1; L i No. i Thickness of formation uplift or compression in adjacent well No.

[0048] The second technical solution of the present invention is achieved through the following measures: a ground collapse pressure calculation device combining seismic wave velocity and fault effect, comprising:

[0049] The data acquisition module obtains the depth pressure and transverse / longitudinal wave velocity ratio of the target well.

[0050] The calculation formula establishment module establishes a collapse pressure calculation formula based on the relationship between collapse pressure, depth pressure, and tectonic influence.

[0051] The collapse pressure calculation module calculates the formation collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure calculation formula.

[0052] The formula for calculating the collapse pressure is:

[0053]

[0054] In the formula, P c The collapse pressure is expressed in MPa. P z For depth pressure, MPa; The ratio of transverse to longitudinal wave velocities is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa. T To construct the correction value, MPa.

[0055] The following are further optimizations and / or improvements to the second technical solution of the above invention:

[0056] The above data acquisition module includes:

[0057] The data acquisition unit obtains formation density by combining well logging data with pre-stack seismic gather inversion. , transverse wave V s longitudinal waves V p ;

[0058] Transverse and longitudinal wave velocity ratio unit, composed of transverse waves V s and longitudinal waves V p The transverse and longitudinal wave velocities were calculated.

[0059] The depth pressure calculation unit calculates the depth pressure according to the following formula.

[0060]

[0061] In the formula, P z For depth pressure, MPa; Formation density, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H The depth of the well is in meters (m).

[0062] The module for establishing the above calculation formula includes:

[0063] The regional formation coefficient determination unit determines the regional formation coefficient based on the collapse pressure measured in drilling experiments and the collapse pressure monitored while drilling.

[0064] The rock deformation threshold determination unit determines the rock deformation threshold value based on the transverse and longitudinal wave velocity ratio of the gentle and structurally disturbed strata in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling.

[0065] The structural correction value determination unit determines the structural correction value based on the formation uplift or compression thickness and the collapse pressure data monitored while drilling in adjacent wells;

[0066] The formula establishment unit establishes a formula for calculating collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, tectonic correction value, regional stratigraphic coefficient, and rock deformation threshold value.

[0067] This invention provides a method for calculating formation collapse pressure by combining seismic wave velocity and fault effect. It deeply explores the rock physical characteristics of seismic wave velocity response, uses fault activity effect to express the formation stress balance state, and replaces the complex and difficult-to-measure rock elastic parameters in the traditional Mohr-Coulomb criterion with transverse and longitudinal wave ratios and fault effect parameters. This greatly simplifies the calculation process, significantly reduces the difficulty of parameter acquisition, and has multiple advantages such as simple operation, high timeliness, high calculation efficiency, and excellent accuracy. It provides an innovative solution for the rapid and accurate calculation of formation collapse pressure in drilling engineering. Attached Figure Description

[0068] Appendix Figure 1 This is a schematic diagram of the ground collapse pressure calculation device that combines seismic wave velocity and fault effect according to the present invention.

[0069] Appendix Figure 2 This is a schematic diagram illustrating the process of determining the formation density and transverse / longitudinal wave velocity ratio in well M51 in Embodiment 11 of the present invention.

[0070] Appendix Figure 3 This is a cross-sectional view of the transverse and longitudinal wave velocity ratio of well M51 in Embodiment 11 of the present invention.

[0071] Appendix Figure 4 This is a formation density profile of well M51 in Embodiment 11 of the present invention.

[0072] Appendix Figure 5 This is a statistical diagram of the stratigraphic coefficients of the experimental area to which well M51 belongs in Embodiment 11 of the present invention.

[0073] Appendix Figure 6 This is a location diagram of wells B1, C1, and D1 in Embodiment 11 of the present invention, specifically for wells M6, M5, and M504.

[0074] Appendix Figure 7 This is a cross-sectional view of the structural location of well M51 and adjacent wells in Embodiment 11 of the present invention.

[0075] Appendix Figure 8 This is a schematic diagram of the formation uplift measurement in well M51 and adjacent wells in Embodiment 11 of the present invention. Detailed Implementation

[0076] 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.

[0077] The present invention will be further described below with reference to embodiments:

[0078] Example 1: This method for calculating stratum collapse pressure by combining seismic wave velocity and fault effect includes the following steps:

[0079] Obtain the depth pressure and transverse / longitudinal wave velocity ratio of the target well.

[0080] A formula for calculating collapse pressure is established based on the relationship between collapse pressure, depth pressure, and tectonic influence.

[0081] The formation collapse pressure is calculated based on the formulas for depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure.

[0082] The formula for calculating the collapse pressure is:

[0083]

[0084] In the formula, P c The collapse pressure is expressed in MPa. P z For depth pressure, MPa; The ratio of transverse to longitudinal wave velocities is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa. T To construct the correction value, MPa.

[0085] Example 2: As an optimization of the above example, obtaining the depth pressure and transverse / longitudinal wave velocity ratio of the target drilling well includes:

[0086] Formation density was obtained by combining well logging data with pre-stack seismic gather inversion. , transverse wave V s longitudinal waves V p ;

[0087] by transverse waves V s and longitudinal waves V p The transverse and longitudinal wave velocities were calculated.

[0088] The depth pressure is calculated using the following formula.

[0089]

[0090] In the formula, P z For depth pressure, MPa; Formation density, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H The depth of the well is in meters (m).

[0091] Example 3: As an optimization of the above examples, a formula for calculating collapse pressure is established based on the relationship between collapse pressure, depth pressure, and tectonic influence, including:

[0092] The regional formation coefficient is determined based on the collapse pressure measured in the drilling experiment and the collapse pressure monitored while drilling.

[0093] Based on the ratio of transverse and longitudinal wave velocities in the gently sloping formation with minimal tectonic disturbance in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling, the rock deformation threshold value is determined.

[0094] The structural correction value is determined based on the formation uplift or compression thickness and the collapse pressure data monitored during drilling in adjacent wells;

[0095] A formula for calculating collapse pressure is established based on depth pressure, the ratio of transverse to longitudinal wave velocities, tectonic correction values, regional stratigraphic coefficients, and rock deformation threshold values.

[0096] Example 4: As an optimization of the above examples, the regional formation coefficient is determined based on the collapse pressure measured in the drilling experiment and the collapse pressure monitored while drilling. This includes calculating the regional formation coefficient using the following formula.

[0097]

[0098] In the formula, R This is a regional stratigraphic coefficient, dimensionless. P ct The collapse pressure, measured during drilling, is MPa. P cs The collapse pressure, measured in MPa, is the pressure obtained from the drilling experiment.

[0099] Example 5: As an optimization of the above examples, based on the transverse and longitudinal wave velocity ratios of gently sloping formations with minimal tectonic disturbance in the target drilling area, the collapse pressure monitored during drilling, and the depth pressure, a rock deformation threshold value is determined, including:

[0100] In the area where the target well is located, select gentle strata with minimal tectonic disturbance as the data acquisition strata;

[0101] The data acquisition formation's transverse and longitudinal wave velocity ratios, as well as the collapse pressure and depth pressure monitored during drilling, were obtained.

[0102] The rock deformation threshold value in the target drilling area is obtained by back-calculation using the following formula;

[0103]

[0104] In the formula, The collapse pressure (MPa) of the formation monitored during drilling for data acquisition. The depth pressure of the formation used for data acquisition is measured in MPa. The ratio of transverse and longitudinal wave velocities in the data acquisition strata is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c Rock deformation threshold, MPa.

[0105] Example 6: As an optimization of the above examples, based on the formation uplift or compression thickness and the collapse pressure data monitored while drilling in adjacent wells, a structural correction value is determined, including:

[0106] The construction correction value is calculated using the following formula:

[0107]

[0108] In the formula, T To construct the correction value, MPa; k The pressure reduction or enhancement coefficient for the fault is expressed in MPa / m. L The thickness of the strata due to uplift or compression is measured in meters (m).

[0109] Example 7: As an optimization of the above examples, the fault decompression or pressurization coefficient k Determine by following these steps:

[0110] Obtain the collapse pressure data while drilling from adjacent wells in the region with similar structures to the target well, and calculate the structural correction value for the adjacent wells using the following formula. T i ,

[0111]

[0112] In the formula, T i For the first i Structural correction value for adjacent well No. , MPa; P ci For the first i The collapse pressure monitored during drilling of the adjacent well, in MPa; For the first i Formation density of adjacent well #, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H i For the first i The depth of the adjacent well, in meters; For the first i The ratio of transverse and longitudinal wave velocities of adjacent wells is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa.

[0113] The first was obtained through seismic profile measurements. i Formation uplift or compression thickness of adjacent well No. L i ;

[0114] Based on the structural correction value of adjacent wells T iFormation uplift or compression thickness with adjacent wells L i The fault decompression or pressurization coefficient is obtained according to the following formula. k :

[0115]

[0116] In the formula, d i For the first i The distance from the adjacent well to the target well, in meters; The weighting factor is dimensionless. T i For the first i Structural correction value for adjacent well No. 1; L i No. i Thickness of formation uplift or compression in adjacent well No.

[0117] Example 8: As Figure 1 As shown, the ground collapse pressure calculation device combining seismic wave velocity and fault effect includes:

[0118] The data acquisition module obtains the depth pressure and transverse / longitudinal wave velocity ratio of the target well.

[0119] The calculation formula establishment module establishes a collapse pressure calculation formula based on the relationship between collapse pressure, depth pressure, and tectonic influence.

[0120] The collapse pressure calculation module calculates the formation collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure calculation formula.

[0121] The formula for calculating the collapse pressure is:

[0122]

[0123] In the formula, P c The collapse pressure is expressed in MPa. P z For depth pressure, MPa; The ratio of transverse to longitudinal wave velocities is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa. T To construct the correction value, MPa.

[0124] Example 9: As an optimization of the above embodiments, the data acquisition module includes:

[0125] The data acquisition unit obtains formation density by combining well logging data with pre-stack seismic gather inversion. , transverse wave Vs longitudinal waves V p ;

[0126] Transverse and longitudinal wave velocity ratio unit, composed of transverse waves V s and longitudinal waves V p The transverse and longitudinal wave velocities were calculated.

[0127] The depth pressure calculation unit calculates the depth pressure according to the following formula.

[0128]

[0129] In the formula, P z For depth pressure, MPa; Formation density, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H The depth of the well is in meters (m).

[0130] Example 10: As an optimization of the above embodiments, the calculation formula establishment module includes:

[0131] The regional formation coefficient determination unit determines the regional formation coefficient based on the collapse pressure measured in drilling experiments and the collapse pressure monitored while drilling.

[0132] The rock deformation threshold determination unit determines the rock deformation threshold value based on the transverse and longitudinal wave velocity ratio of the gentle and structurally disturbed strata in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling.

[0133] The structural correction value determination unit determines the structural correction value based on the formation uplift or compression thickness and the collapse pressure data monitored while drilling in adjacent wells;

[0134] The formula establishment unit establishes a formula for calculating collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, tectonic correction value, regional stratigraphic coefficient, and rock deformation threshold value.

[0135] This invention addresses the challenge of calculating strata collapse pressure in deep strata, fault fracture zones, and complex structural regions by providing a method that combines seismic wave velocity and fault effects. In deep, high-temperature, and high-pressure strata, the mechanical properties of rocks are altered by complex physicochemical processes, making it difficult to obtain accurate parameters using traditional methods. Within fault fracture zones, rock integrity is poor and stress distribution is disordered, rendering conventional calculation models unable to reflect the true mechanical state. Furthermore, in complex structural regions such as folds and thrust faults, the geostress field is affected by the superposition of multiple tectonic movements, further increasing the complexity and uncertainty of collapse pressure calculation. Therefore, this invention develops a highly user-friendly, accurate, and practical method for calculating strata collapse pressure. By cleverly transforming complex and profound geomechanical principles into simple calculation and judgment logic based on intuitively measurable key parameters such as seismic wave velocity, fault uplift height, and shear wave direction, this method enables even ordinary engineering technicians without extensive professional backgrounds to quickly and conveniently estimate strata collapse pressure and determine potential collapse hazard locations. This provides timely and reliable data support for key decisions such as mud density adjustment and support structure design during underground engineering construction, effectively reducing the risk of engineering accidents, significantly saving engineering costs, and promoting technological progress and development in the field of underground engineering construction.

[0136] Example 11: The process of establishing this method for calculating stratum collapse pressure by combining seismic wave velocity and fault effect is as follows:

[0137] The calculation of formation collapse pressure is essentially a quantitative assessment of a formation's ability to resist instability and failure under the influence of various factors. Depth pressure represents the stress generated by the formation's own weight and is a fundamental component of formation collapse pressure. Seismic wave velocity (P-wave velocity) V p and transverse wave velocity V s The stress modulus is closely related to the mechanical properties of the strata, such as the elastic modulus and shear modulus. The ratio of these two values ​​reflects the elastic and shear characteristics of the strata rocks, thus demonstrating the strata's ability to resist collapse. Fault activity disrupts the original stress balance of the strata, leading to a redistribution of stress. When a fault is uplifted during activity, rock stress decreases, and the strata collapse pressure decreases. Conversely, when the strata are compressed, the rocks become more compact, and the strata collapse pressure increases. Therefore, tectonic correction needs to be included as an important adjustment factor in the calculation of strata collapse pressure to obtain an accurate assessment.

[0138] Based on extensive data research, it has been found that ground collapse pressure P c With deep pressure P z There is a linear relationship between the structural effects and the influence of the structure, that is:

[0139]

[0140] In the formula R and T The coefficients are to be determined.

[0141] Simultaneously considering the elastic and shear properties of the rock layers (ratio of transverse to longitudinal wave velocities) The impact of this on formation collapse pressure further extends the calculation of formation collapse pressure as follows:

[0142]

[0143] In the formula, P c The collapse pressure is expressed in MPa. P z For depth pressure, MPa; The ratio of transverse to longitudinal wave velocities is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c The rock deformation threshold value is given in MPa. T To construct the correction value, MPa.

[0144] Among them, deep pressure P z :

[0145]

[0146] In the formula, P z For depth pressure, MPa; Formation density, g / cm³ 3 ; The acceleration due to gravity is expressed in m / s². H The depth of the well is in meters (m).

[0147] Construct correction value T :

[0148]

[0149] In the formula, T To construct the correction value, MPa; k The pressure reduction or enhancement coefficient for the fault is expressed in MPa / m. L The thickness of the strata due to uplift or compression is measured in meters (m).

[0150] Therefore, by integrating depth-weighted formation depth pressure, parameters reflecting the influence of seismic wave velocity, and adjustment terms reflecting fault activity, and based on the accumulation of extensive practical engineering data and in-depth geomechanical theoretical research, the collapse pressure calculation formula, after repeated verification and optimization, can be expressed as:

[0151]

[0152] Among them, formation density , transverse wave V s longitudinal waves V p The three parameters can be obtained by establishing a rock physics model from well logging data and then combining it with pre-stack seismic gather inversion.

[0153] Regional stratigraphic coefficient R The ratio of the collapse pressure measured by drilling experiments to the collapse pressure calculated from drilling monitoring is used to determine the value of the collapse pressure.

[0154]

[0155] In the formula, R This is a regional stratigraphic coefficient, dimensionless. P ct The collapse pressure, measured during drilling, is MPa. P cs The collapse pressure, measured in MPa, is the pressure obtained from the drilling experiment.

[0156] The process for determining the rock deformation threshold value c is as follows:

[0157] In the area where the target well is located, select gentle strata with minimal tectonic disturbance as the data acquisition strata;

[0158] The data acquisition formation's transverse and longitudinal wave velocity ratios, as well as the collapse pressure and depth pressure monitored during drilling, were obtained.

[0159] Since these types of flat strata with minimal tectonic disturbance are not affected by fault activity, the tectonic correction term T in Equation 1 takes the value of 0. Therefore, Equation 1 can be converted into Equation 5 below, and the rock deformation threshold value in the target drilling area can be calculated in reverse.

[0160]

[0161] In the formula, The collapse pressure (MPa) of the formation monitored during drilling for data acquisition. The depth pressure of the formation used for data acquisition is measured in MPa. The ratio of transverse and longitudinal wave velocities in the data acquisition strata is dimensionless. R This is a regional stratigraphic coefficient, dimensionless. c Rock deformation threshold, MPa.

[0162] Fault decompression or pressurization coefficient k And the thickness of the formation uplift or compression L The steps to determine this are as follows:

[0163] When a fault is active, the rock is uplifted, reducing rock stress and lowering collapse pressure. k represents The coefficient of fault decompression, L This indicates the height of uplift of the strata in the hanging wall of the fault; when the strata are compressed, the rock becomes more compact, and the pressure for collapse increases. k The coefficient representing fault pressurization. L It indicates the difference in stratum thickness at the same level on the hanging wall and footwall of a fault. L This can be obtained through seismic profile measurements. k The value utilizes collapse pressure data from 3 to 5 adjacent wells with similar structures to the target well, monitored while drilling, and then uses a formula... (Equation 6) Back-calculate the structural correction value of adjacent wells T i In seismic profile measurement L i And assumes based on distance d i The weighting factor is ( d i For the serial number i The horizontal distance between the well and the predicted well is measurable in the seismic profile, and the fault decompression or pressurization coefficient is obtained by weighted averaging based on weighting factors. (Equation 7).

[0164] Example 12: The specific implementation process of this method for calculating stratum collapse pressure by combining seismic wave velocity and fault effect is as follows:

[0165] (1) Basic parameter: formation density transverse and longitudinal wave velocity ratio Acquisition

[0166] like Figure 2 As shown, pre-stack seismic inversion was first performed using well logging and seismic data to obtain the three-dimensional S-wave and P-wave velocity ratio and formation density data volumes for well M51. Within these data volumes, the S-wave and P-wave velocity ratio profiles and formation density profiles for well M51 are extracted as follows: Figure 3 and Figure 4 As shown, the formation density at point A of well M51 was read in the profile. 2.35 g / cm 3 transverse and longitudinal wave velocities It is 2.045.

[0167] (2) Regional stratigraphic coefficient R The determination

[0168] In the experimental area, 52 data points from 43 wells with collapse pressure data obtained through drilling monitoring and experimental measurements were selected within the time range of 2018 to 2024.

[0169] First, based on the formula (Equation 4) Calculate the 53 data points respectively. R Value. According to statistics (see...) Figure 5 ), shallow loose strata ( H <2750m), collapse pressure monitored while drilling P ct Collapse pressure measured in drilling experiments P cs The average ratio is 0.8; deep compacted strata ( H >2750m), collapse pressure monitored while drilling P ct Collapse pressure measured in drilling experiments P cs The average ratio is 1.2. Therefore, the empirical stratigraphic coefficient for this experimental area is... R shallow ( H <2750m) take 0.8, deep layer H (>2750m) Take 1.2.

[0170] (3) Determination of rock deformation threshold value c

[0171] Three points, B1, C1, and D1, were selected in the stable formation above the trajectories of wells M6, M5, and M504 (see...). Figure 6 The three drilling depths were 767m, 772m, and 882m, respectively; the collapse pressures monitored during drilling were 17.9MPa, 17.57MPa, and 18.82MPa, respectively; and the density values ​​were 2.08g / cm³. 3 2.07 g / cm 3 2.03 g / cm 3 The longitudinal and transverse wave velocity ratios are 1.65, 1.68, and 1.62, respectively; the stratigraphic coefficient R is taken as 0.8. Substituting these values ​​into Equation 5, the rock deformation threshold value c is calculated. Since the three points B1, C1, and D1 are less affected by tectonic disturbance, the rock deformation threshold value c values ​​for the three sample points are 2.994 MPa, 3.026 MPa, and 2.971 MPa, respectively. The average value of the three values ​​is taken as c = 3 MPa.

[0172] (4) Fault decompression coefficient k The determination

[0173] Interpret the structural morphology of the P-layer geological stratum at measuring point A on the seismic profile of well M51, and identify the large faults influencing the structure of this area to determine the structural location. Well M51 is located on the hanging wall of the fault. According to the fault effect: the strata are uplifted, rock stress decreases, and collapse pressure decreases. Therefore, adjacent wells M6, M5, and M504, which are located on the same hanging wall as M51, are selected. Figure 7 ), calculate the structural corrections for the three well trajectories passing through the P layer at depths of 2600m, 2617m, and 2730m respectively. Ti and fault decompression coefficient k i Let the three measurement points be B, C, and D.

[0174] The collapse pressures monitored during drilling at points B, C, and D in wells M6, M5, and M504 were 38.21 MPa, 39.01 MPa, and 53.11 MPa, respectively, and their density values ​​in the density inversion volume were 2.37 g / cm³. 3 2.32 g / cm 3 2.30g / cm 3 The transverse and longitudinal wave velocities are compared to those read from the inverted body. The values ​​are 2.123, 2.075, and 1.96, respectively, representing regional stratigraphic coefficients. R Take 0.8.

[0175] According to the formula (Equation 6) yields:

[0176]

[0177] In the seismic profile, the footwall of layer P is flattened, and a horizontal extension line of the footwall of layer P is drawn to the footwall, such as... Figure 8 As shown, the vertical distances from the intersection of the horizontal extension of the footwall of layer P and the well trajectory to points B, C, D, and A are obtained by measuring the seismic profile. L B =135 m , L C =118 m , L D =16 m , L C =133 m The calculated formation decompression coefficients at points B, C, and D are as follows:

[0178]

[0179] Based on distance d i The weighting factor is , d i For the first i The horizontal distance from well M6 to well M51 is the same as the horizontal distance from well M51 to well M6. d B =1331m, horizontal distance between well M5 and well M51 d C =1244m, the horizontal distance between well M504 and well M51 d D=3970m, and the decompression coefficient at point A of well M51 is predicted by weighted average based on the weighting factor. k A for:

[0180]

[0181] (4) Calculation of formation collapse pressure:

[0182] Calculate the formation collapse pressure at 2610m in well M51 according to Equation 8:

[0183]

[0184] The calculated formation collapse pressure at point A of well M51 was 36.582 MPa, while the post-drilling measured value was 33.66 MPa, with an error rate of 8.68%, indicating a high degree of agreement.

[0185] In summary, this invention provides a method for calculating formation collapse pressure by combining seismic wave velocity and fault effects. It deeply integrates knowledge from multiple disciplines such as geological engineering, geophysics, and petroleum exploration engineering. Based on the propagation characteristics of seismic shear waves and longitudinal waves in underground media, and combined with the stress change effect caused by fault activity, it innovatively proposes a method for quickly and accurately calculating formation collapse pressure and scientifically determining the location of collapse hazards. This method can be widely and effectively applied to wellbore stability analysis and mud density optimization decisions in oil and gas drilling engineering.

[0186] The above technical features constitute the preferred embodiment of the present invention, which has strong adaptability and optimal implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A method for calculating ground collapse pressure by combining seismic wave velocity and fault effect, characterized in that... Includes the following steps: Obtain the depth pressure and transverse / longitudinal wave velocity ratio of the target well. A formula for calculating collapse pressure is established based on the relationship between collapse pressure, depth pressure, and tectonic influence. The formation collapse pressure is calculated based on the formulas for depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure. The formula for calculating the collapse pressure is: In the formula, The collapse pressure is expressed in MPa. For depth pressure, MPa; R is the ratio of transverse to longitudinal wave velocities, dimensionless; R is the regional stratigraphic coefficient, dimensionless. c represents the rock deformation threshold value, in MPa; T is the construction correction value, in MPa; The process of obtaining the depth pressure and transverse / longitudinal wave velocity ratio of the target well includes: Formation density was obtained by combining well logging data with pre-stack seismic gather inversion. , transverse wave longitudinal waves ; by transverse waves and longitudinal waves The transverse and longitudinal wave velocities were calculated. The depth pressure is calculated using the following formula. In the formula, For depth pressure, MPa; For the formation density, 10 6 g / m 3 ; ρ is the acceleration due to gravity, m / s²; H is the well depth, m.

2. The method for calculating stratum collapse pressure by combining seismic wave velocity and fault effect according to claim 1, characterized in that... A formula for calculating collapse pressure is established based on the relationship between collapse pressure, depth pressure, and tectonic influences, including: The regional formation coefficient is determined based on the collapse pressure measured in the drilling experiment and the collapse pressure monitored while drilling. Based on the ratio of transverse and longitudinal wave velocities in the gently sloping formation with minimal tectonic disturbance in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling, the rock deformation threshold value is determined. The structural correction value is determined based on the formation uplift or compression thickness and the collapse pressure data monitored during drilling in adjacent wells; A formula for calculating collapse pressure is established based on depth pressure, the ratio of transverse to longitudinal wave velocities, tectonic correction values, regional stratigraphic coefficients, and rock deformation threshold values.

3. The method for calculating stratum collapse pressure combining seismic wave velocity and fault effect according to claim 2, characterized in that... Based on the collapse pressure measured in drilling experiments and the collapse pressure monitored while drilling, the regional formation coefficient is determined, including: the regional formation coefficient is calculated using the following formula. In the formula, R is the regional stratigraphic coefficient, which is dimensionless; The collapse pressure, measured during drilling, is MPa. The collapse pressure, measured in MPa, is the pressure obtained from the drilling experiment.

4. The method for calculating stratum collapse pressure combining seismic wave velocity and fault effect according to claim 2 or 3, characterized in that... Based on the transverse and longitudinal wave velocity ratios of gently sloping formations with minimal tectonic disturbance in the target drilling area, and the collapse pressure and depth pressure monitored during drilling, rock deformation thresholds are determined, including: In the area where the target well is located, select gentle strata with minimal tectonic disturbance as the data acquisition strata; The data acquisition formation's transverse and longitudinal wave velocity ratios, as well as the collapse pressure and depth pressure monitored during drilling, were obtained. The rock deformation threshold value in the target drilling area is obtained by back-calculation using the following formula; In the formula, The collapse pressure (MPa) of the formation monitored during drilling for data acquisition. The depth pressure of the formation used for data acquisition is measured in MPa. R is the ratio of transverse and longitudinal wave velocities in the data acquisition strata, dimensionless; R is the regional stratigraphic coefficient, dimensionless; c is the rock deformation threshold value, MPa.

5. The method for calculating stratum collapse pressure combining seismic wave velocity and fault effect according to claim 2, characterized in that... Based on the formation uplift or compression thickness and the collapse pressure data monitored during drilling in adjacent wells, structural correction values ​​are determined, including: The construction correction value is calculated using the following formula: In the formula, T is the structural correction value, MPa; k is the fault decompression or pressurization coefficient, MPa / m; and L is the formation uplift or compression thickness, m.

6. The method for calculating stratum collapse pressure combining seismic wave velocity and fault effect according to claim 5, characterized in that... The fault decompression or pressurization coefficient k is determined according to the following steps: Obtain the collapse pressure data while drilling from adjacent wells in the region with similar structures to the target well, and calculate the structural correction value for the adjacent wells using the following formula. , In the formula, Let be the structural correction value for the i-th adjacent well, in MPa; The collapse pressure during drilling monitoring of the i-th adjacent well is given in MPa. Let be the formation density of the i-th adjacent well, 10 6 g / m 3 ; The acceleration due to gravity is expressed in m / s². Let the depth of the i-th adjacent well be m; R is the ratio of transverse and longitudinal wave velocities of the i-th adjacent well, dimensionless; R is the regional stratigraphic coefficient, dimensionless; c is the rock deformation threshold value, MPa; The formation uplift or compression thickness of the i-th adjacent well was obtained through seismic profile measurements. ; Based on the structural correction value of adjacent wells Formation uplift or compression thickness with adjacent wells The fault decompression or pressurization coefficient k is obtained according to the following formula: In the formula, Let be the distance, in meters, from the i-th adjacent well to the target well. The weighting factor is dimensionless. This is the structural correction value for the i-th adjacent well; Thickness of formation uplift or compression in adjacent well i.

7. A device for calculating stratum collapse pressure combining seismic wave velocity and fault effect, wherein the device uses the stratum collapse pressure calculation method combining seismic wave velocity and fault effect as described in any one of claims 1 to 6, characterized in that... include: The data acquisition module obtains the depth pressure and transverse / longitudinal wave velocity ratio of the target well. The calculation formula establishment module establishes a collapse pressure calculation formula based on the relationship between collapse pressure, depth pressure, and tectonic influence. The collapse pressure calculation module calculates the formation collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, and collapse pressure calculation formula. The formula for calculating the collapse pressure is: In the formula, The collapse pressure is expressed in MPa. For depth pressure, MPa; R is the ratio of transverse to longitudinal wave velocities, dimensionless; R is the regional stratigraphic coefficient, dimensionless. c represents the rock deformation threshold value, in MPa; T is the construction correction value, in MPa; The data acquisition module includes: The data acquisition unit obtains formation density by combining well logging data with pre-stack seismic gather inversion. , transverse wave longitudinal waves ; Transverse and longitudinal wave velocity ratio unit, composed of transverse waves and longitudinal waves The transverse and longitudinal wave velocities were calculated. The depth pressure calculation unit calculates the depth pressure according to the following formula. In the formula, For depth pressure, MPa; For the formation density, 10 6 g / m 3 ; ρ is the acceleration due to gravity, m / s²; H is the well depth, m.

8. The ground collapse pressure calculation device combining seismic wave velocity and fault effect according to claim 7, characterized in that... The calculation formula creation module includes: The regional formation coefficient determination unit determines the regional formation coefficient based on the collapse pressure measured in drilling experiments and the collapse pressure monitored while drilling. The rock deformation threshold determination unit determines the rock deformation threshold value based on the transverse and longitudinal wave velocity ratio of the gentle and structurally disturbed strata in the target drilling area, as well as the collapse pressure and depth pressure monitored during drilling. The structural correction value determination unit determines the structural correction value based on the formation uplift or compression thickness and the collapse pressure data monitored while drilling in adjacent wells; The formula establishment unit establishes a formula for calculating collapse pressure based on depth pressure, transverse and longitudinal wave velocity ratio, tectonic correction value, regional stratigraphic coefficient, and rock deformation threshold value.

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