Method and system for evaluating collapse pressure of well wall of infilled well

Abstract

The invention discloses a method and system for evaluating collapse pressure of a well wall of an infilled well, and the method comprises the steps: calculating a well periphery stress component of an anisotropic stratum according to rock mechanical parameters of a to-be-evaluated region and a reservoir three-dimensional geomechanical model loaded with a well track of the infilled well; according to the well periphery stress component of the anisotropic stratum and the reservoir three-dimensional geomechanical model, the collapse pressure under the well track condition of the infilled well is calculated; collapse pressure under different well tracks of the infilled well is formed by adjusting the well tracks of the infilled well, and a well drilling design scheme of the infilled well is guided on the basis of the collapse pressure. According to the method, the influence of anisotropy on the stability of the well wall of the infilled well is fully considered, the drilling design scheme of the infilled well is carried out according to the collapse pressure under different well track of the infilled well, and the stability of the well wall of drilling of the infilled well can be improved, so that drilling accidents are reduced, and safe and efficient drilling of the infilled well is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling engineering technology, and in particular to a method and system for evaluating wellbore collapse pressure in infill wells. Background Technology

[0002] To effectively develop shale oil and gas reservoirs, horizontal drilling and volumetric fracturing techniques are commonly employed. However, with the continued development of shale oil and gas reservoirs, fracturing wells have gradually revealed problems such as limited fracture-controlled reservoirs and excessively rapid declines in gas production. Considering the large well network and high residual reservoir levels in the early stages of development, infill wells with volumetric fracturing in unconventional oil and gas reservoirs such as shale can effectively increase the degree of inter-well stimulation of the entire reservoir and achieve breakthroughs in residual reserves.

[0003] Typically, when horizontal wells penetrate weak shale formations, and as old wells experience depletion and production, stress exhaustion and inversion occur around the wellbore. At the same time, the intensity and duration of production can cause significant differences in the stress field, which in turn can affect the wellbore stability of subsequent infill wells.

[0004] Currently, when designing infill wells, the main considerations are the pre-planned fracturing and production enhancement effects in the later stages of infill well drilling, with less emphasis on optimizing the design from the perspective of wellbore stability.

[0005] For densely fractured well platforms, the continuous decline in formation pressure of the parent well during long-term oil and gas production has a significant impact on formation pressure, thus altering the wellbore stability of infill wells. However, current research on infill wellbore stability is limited. Furthermore, shale formation is often influenced by various factors, resulting in one or more sets of directional joints and fractures, exhibiting strong anisotropy. However, current research on the wellbore stability of anisotropic shale infill wells is also limited. Summary of the Invention

[0006] The purpose of this invention is to provide a scheme that considers the influence of anisotropy on the wellbore stability during infill well drilling design, in order to solve the problem that existing infill well drilling designs rarely study the influence of anisotropy on the wellbore stability.

[0007] To address the aforementioned technical problems, embodiments of the present invention provide a method for evaluating wellbore collapse pressure in infill wells. The method includes: calculating the wellbore stress components of anisotropic formations based on the rock mechanics parameters of the area to be evaluated and a three-dimensional geomechanical model of the reservoir loaded with the infill wellbore trajectory; calculating the collapse pressure under the infill wellbore trajectory conditions based on the wellbore stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir; adjusting the infill wellbore trajectory to form collapse pressures under different infill wellbore trajectories, and using this to guide the infill well drilling design scheme.

[0008] Optionally, the reservoir three-dimensional geomechanical model is constructed using the following steps: Based on the basic measurement data of the area to be evaluated, a three-dimensional fine geological model of the area to be evaluated is established; based on the basic measurement data, key reservoir attributes are obtained using numerical simulation methods, and these key attributes are added to the three-dimensional fine geological model to construct a reservoir attribute model; based on the basic measurement data, the correspondence between reservoir attributes and rock mechanical attributes is analyzed, and this correspondence is added to the reservoir attribute model to construct a three-dimensional rock mechanical model; based on the structural parameters and rock mechanical parameters of the area to be evaluated, a three-dimensional geostress model is constructed using a mesh interaction algorithm and a finite element algorithm, and based on the three-dimensional geostress model and the three-dimensional rock mechanical model, a reservoir three-dimensional geomechanical model is constructed.

[0009] Optionally, the basic measurement data includes, but is not limited to, well logging parameters, well logging parameters, and seismic parameters. The step of obtaining key reservoir attributes using numerical simulation methods based on the basic measurement data of the area to be evaluated includes: obtaining geological attributes describing the area to be evaluated based on the seismic parameters; obtaining lithological spatial variation characteristics describing the area to be evaluated using Kriging interpolation based on the seismic parameters and the well logging parameters; obtaining lithological distribution characteristics of the area to be evaluated based on the geological attribute distribution characteristics and the lithological spatial variation characteristics; and performing numerical simulation based on the well logging parameters, using the lithological distribution characteristics as constraints, to obtain the key reservoir attributes.

[0010] Optionally, the step of constructing a three-dimensional geostress model based on the structural parameters and rock mechanics parameters of the area to be evaluated using a mesh interaction algorithm and a finite element algorithm includes: importing the structural parameters into the finite element model using the finite element method, and importing the rock mechanics parameters into the finite element model using the mesh interaction algorithm, wherein the structural parameters include underground structures and geological structures; performing geostress simulation calculations on the finite element model with the imported structural parameters and rock mechanics parameters to construct a three-dimensional geostress model.

[0011] Optionally, the rock mechanical parameters of the area to be evaluated are obtained through the following steps: based on the three-dimensional rock mechanical model in the three-dimensional geomechanical model of the reservoir, reservoir inversion is performed on the reservoir of the area to be evaluated to obtain the rock mechanical parameters; the rock mechanical parameters are adjusted by conducting triaxial experiments and shear tests on the core of the reservoir of the area to be evaluated, and the rock mechanical parameters include elastic modulus, Poisson's ratio, Lamé constant, cohesion and internal friction.

[0012] Optionally, the step of calculating the collapse pressure under the infill well trajectory conditions based on the wellbore stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir includes: importing the wellbore stress components of the anisotropic formation into the three-dimensional geomechanical model of the reservoir, and calculating the matrix critical bottom-hole pressure and the weak-face boundary bottom-hole pressure by combining the Mogi-Column criterion and the Jaeger weak-face criterion; and taking the minimum value among the matrix critical bottom-hole pressure, the weak-face boundary bottom-hole pressure, and the reservoir pore pressure distribution as the collapse pressure under the current infill well trajectory conditions.

[0013] Optionally, the step of calculating the wellbore stress components of anisotropic formations includes: extracting three-dimensional geostress distribution characteristics based on the rock mechanics parameters and the reservoir three-dimensional geomechanical model; performing multiple rounds of coordinate system transformation on the three-dimensional geostress distribution characteristics to obtain the wellbore stress components of anisotropic formations in the target coordinate system, wherein the multiple rounds of coordinate system transformation are performed sequentially from the geodetic coordinate system to the wellbore rectangular coordinate system and from the wellbore rectangular coordinate system to the wellbore polar coordinate system.

[0014] Optionally, the step of guiding the drilling design scheme of infill wells based on the collapse pressure under different infill well trajectories includes: step S1, adjusting the inclination angle and azimuth angle in the infill well trajectory to update the three-dimensional geomechanical model of the reservoir; step S2, obtaining the critical drilling mud density based on the updated three-dimensional geomechanical model; step S3, continuously repeating steps S1 and S2, and determining the drilling design scheme of infill wells in the area to be evaluated based on the critical drilling mud density under different infill well trajectory conditions.

[0015] On the other hand, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method described in any one or more of the above embodiments.

[0016] Furthermore, embodiments of the present invention also provide a system for evaluating wellbore collapse pressure in infill wells. The system includes: a wellbore stress component calculation module, configured to calculate the wellbore stress components of anisotropic formations based on the rock mechanics parameters of the area to be evaluated and a three-dimensional geomechanical model of the reservoir loaded with the wellbore trajectory of the infill well; a collapse pressure calculation module, configured to calculate the collapse pressure under the wellbore trajectory conditions of the infill well based on the wellbore stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir; and an infill well drilling scheme generation module, configured to generate collapse pressures under different infill well trajectories by adjusting the wellbore trajectory of the infill well, and to guide the infill well drilling design scheme based on this.

[0017] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0018] This invention proposes a method and system for evaluating wellbore collapse pressure in infill wells. This method and system require correction of the inverted rock mechanics parameters through laboratory experiments, thereby improving the ability to update rock mechanics parameters through a combination of experimental and numerical simulation techniques. Compared to pure numerical simulation methods, this approach offers higher accuracy and can effectively guide safe and efficient infill well drilling and subsequent production stimulation. It also considers the significant anisotropy of shale formations and its impact on wellbore stability, and designs infill well drilling schemes based on collapse pressure under different wellbore trajectories. This improves wellbore stability during infill well drilling, thereby reducing drilling accidents and enhancing the efficiency of infill well drilling.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a schematic diagram illustrating the steps of a method for evaluating wellbore collapse pressure according to an embodiment of this application.

[0022] Figure 2 This is a diagram showing the maximum horizontal principal stress data of a three-dimensional geostress model in the method for evaluating wellbore collapse pressure in an embodiment of this application.

[0023] Figure 3This is a diagram of the minimum horizontal principal stress data of a three-dimensional geostress model in the method for evaluating wellbore collapse pressure in an embodiment of this application.

[0024] Figure 4 This is a collapse pressure cloud map extracted from a preset wellbore trajectory for evaluating the collapse pressure of a densified wellbore in an embodiment of this application.

[0025] Figure 5 This is a collapse pressure cloud map of different wellbore trajectories in an infill well, used to evaluate the collapse pressure of the infill wellbore in an embodiment of this application.

[0026] Figure 6 This is a comparison and verification diagram of the calculation results of isotropic and anisotropic collapse pressure in evaluating the collapse pressure of the wellbore in this application embodiment.

[0027] Figure 7 This is a schematic diagram of the system for evaluating wellbore collapse pressure according to an embodiment of this application. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0029] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0031] To effectively develop shale oil and gas reservoirs, horizontal drilling and volumetric fracturing techniques are commonly employed. However, with the continued development of shale oil and gas reservoirs, fracturing wells have gradually revealed problems such as limited fracture-controlled reservoirs and excessively rapid declines in gas production. Considering the large well network and high residual reservoir levels in the early stages of development, infill wells with volumetric fracturing in unconventional oil and gas reservoirs such as shale can effectively increase the degree of inter-well stimulation of the entire reservoir and achieve breakthroughs in residual reserves.

[0032] Typically, when horizontal wells penetrate weak shale formations, and as old wells experience depletion and production, stress exhaustion and inversion occur around the wellbore. At the same time, the intensity and duration of production can cause significant differences in the stress field, which in turn can affect the wellbore stability of subsequent infill wells.

[0033] Currently, when designing infill wells, the main considerations are the pre-planned fracturing and production enhancement effects in the later stages of infill well drilling, with less emphasis on optimizing the design from the perspective of wellbore stability.

[0034] For densely fractured well platforms, the continuous decline in formation pressure of the parent well during long-term oil and gas production has a significant impact on formation pressure, thus altering the wellbore stability of infill wells. However, current research on infill wellbore stability is limited. Furthermore, shale formation is often influenced by various factors, resulting in one or more sets of directional joints and fractures, exhibiting strong anisotropy. However, current research on the wellbore stability of anisotropic shale infill wells is also limited.

[0035] Figure 1 This is a schematic diagram illustrating the steps of a method for evaluating wellbore collapse pressure according to an embodiment of this application. See below for reference. Figure 1 The specific steps and flow of the method for evaluating wellbore collapse pressure in infill wells (hereinafter referred to as the "infill well collapse pressure evaluation method") described in the embodiments of the present invention will be explained.

[0036] Step S110: Calculate the wellbore stress components of anisotropic formations based on the rock mechanics parameters of the area to be evaluated and the three-dimensional geomechanical model of the reservoir with the wellbore trajectory of the infill well.

[0037] A three-dimensional geomechanical model of the reservoir is established, and the pre-made wellbore trajectory of the infill well is loaded into the three-dimensional geomechanical model of the reservoir. Then, based on the rock mechanical parameters of the area to be evaluated by the infill well and the three-dimensional geomechanical model of the reservoir loaded with the wellbore trajectory of the infill well, the well peri-well stress components of the anisotropic formation are calculated.

[0038] In this embodiment, the wellbore trajectory of the encrypted well includes, but is not limited to, the well inclination angle, the wellbore radius, and the azimuth angle.

[0039] In one embodiment, when constructing a three-dimensional geomechanical model of a reservoir, firstly, a detailed three-dimensional geological model of the area to be evaluated is established using basic measurement data of the area. Then, key reservoir attributes are added to the detailed three-dimensional geological model to construct a reservoir attribute model. Furthermore, the correspondence between reservoir attributes and rock mechanical properties is added to the reservoir attribute model to construct a three-dimensional rock mechanical model. Finally, a three-dimensional reservoir in-situ stress model is constructed based on the constructed three-dimensional rock mechanical model and the three-dimensional in-situ stress model. Specifically, the three-dimensional geomechanical model of the reservoir is constructed using the following steps A1-A4:

[0040] Step A1: Based on the basic measurement data of the area to be evaluated, establish a three-dimensional detailed geological model of the area to be evaluated.

[0041] Step A2: Based on the basic measurement data, use numerical simulation methods to obtain the key reservoir attributes, and add the key reservoir attributes to the three-dimensional fine geological model to construct the reservoir attribute model.

[0042] Step A3: Based on the basic measurement data, analyze the correspondence between reservoir properties and rock mechanical properties, add the correspondence to the reservoir property model, and construct a three-dimensional rock mechanical model.

[0043] Step A4: Based on the structural parameters and rock mechanics parameters of the area to be evaluated, a three-dimensional geostress model is constructed using the mesh interaction algorithm and the finite element algorithm. Based on the three-dimensional geostress model and the three-dimensional rock mechanics model, a three-dimensional geomechanical model of the reservoir is constructed.

[0044] The basic measurement data includes, but is not limited to: well logging parameters, well logging parameters, and seismic parameters.

[0045] Specifically, in step A1, based on the drilling data, fault interpretation results, and adjacent layer data comparison of the area to be evaluated, and based on the volume element modeling technology, an accurate block structure model is established. Through logging parameters, well logging parameters, and seismic parameters, and combined with the pilot well layer data, the thickness of each sub-layer is calibrated, thereby realizing a three-dimensional fine geological model containing each sub-layer of anisotropic strata, and constructing a three-dimensional fine geological model.

[0046] Specifically, in step A2, a comprehensive analysis is conducted using various methods and data, such as seismic parameters, to determine the spatial distribution of different lithologies and the variation law of rock physical parameters in the area to be evaluated. Through numerical simulation, key reservoir attributes are obtained, and a reservoir attribute model is constructed based on the key reservoir attributes and the three-dimensional fine geological model.

[0047] In step A2, key reservoir properties include, but are not limited to, porosity, permeability, and gas saturation. In obtaining these key reservoir properties, firstly, the seismic property distribution characteristics and lithological spatial variation characteristics of the area to be evaluated are analyzed, thereby obtaining the lithological distribution characteristics of the area. Numerical simulations are then performed using these lithological distribution characteristics as constraints to obtain the key reservoir properties. Specifically, step A2 includes the following sub-steps A21-A24:

[0048] Sub-step A21: Based on the seismic parameters, obtain the geological properties used to describe the area to be evaluated.

[0049] Sub-step A22: Based on the seismic parameters and logging parameters, the Kriging interpolation method is used to obtain the lithological spatial variation characteristics used to describe the area to be evaluated.

[0050] Sub-step A23: Based on the geological attribute distribution characteristics and lithological spatial variation characteristics, obtain the lithological distribution characteristics of the area to be evaluated.

[0051] Sub-step A24 uses lithological distribution characteristics as constraints and performs numerical simulation based on well logging parameters to obtain key reservoir attributes.

[0052] Specifically, in obtaining key reservoir attributes, when conducting inter-well lithological stochastic simulation using seismic parameters, the distribution patterns of geological attributes can be derived from data such as seismic velocity and density, and these distribution patterns can be applied to the inter-well lithological stochastic simulation. Furthermore, the spatial variability of lithology is described using the Kriging interpolation method based on seismic and logging parameters. By combining neural networks with multi-point statistical analysis methods, the spatial distribution and variability patterns of geological attributes and the spatial variability characteristics of lithology are learned to generate lithological distribution characteristics that conform to actual conditions. Well logging and core parameters are collected, and using the lithological distribution characteristics as constraints, key reservoir attributes are obtained through numerical simulation methods.

[0053] In particular, since geological information data obtained by various means such as seismic parameters, core parameters, and well logging parameters have different formats, preprocessing such as data correction and interpolation is required to ensure data consistency and accuracy, so as to better facilitate subsequent analysis.

[0054] Specifically, in step A3, well logging parameters, seismic parameters, and core parameters are collected. These parameters undergo preprocessing, including data cleaning, outlier handling, and missing value filling, to ensure they meet modeling requirements. The preprocessed parameters are then analyzed to establish a correspondence between reservoir properties and rock mechanical properties. This correspondence is added to the reservoir property model to construct a three-dimensional rock mechanical model. The collected well logging parameters, seismic parameters, and core parameters include, but are not limited to: reservoir shear and p-wave data, density logging data, seismic shear wave impedance, Lamé impedance, and shear impedance.

[0055] In particular, the spatial structure of the reservoir, the distribution of rock mechanical properties, and the characteristics of seismic wave propagation need to be considered when constructing a three-dimensional rock mechanics model.

[0056] In step A4, the construction parameters include underground structure and geological structure.

[0057] In step A4, during the construction of the three-dimensional geostress model, the structural parameters and rock mechanics parameters are first imported into the finite element model. Then, geostress simulation calculations are performed on the finite element model to construct the three-dimensional geostress model. Specifically, step A4 includes the following sub-steps A41-A42:

[0058] Sub-step A41 involves using the finite element method to import the construction parameters into the finite element model, and using the mesh interaction algorithm to import the rock mechanics parameters into the finite element model.

[0059] Sub-step A42 involves performing geostress simulation calculations on the finite element model with imported structural parameters and rock mechanics parameters to construct a three-dimensional geostress model.

[0060] Specifically, by combining seismic interpretation results with the finite element method, the underground structure and geological features are imported into the finite element model. Then, using the mesh interaction algorithm, rock mechanics parameters are imported into the finite element model. The particle swarm algorithm is used to perform finite element numerical calculations, and the three-dimensional geostress model is obtained by iterative solution.

[0061] In particular, mesh adjustment and optimization are necessary during finite element analysis. The mesh size significantly impacts both the calculation results and computational efficiency. An adaptive meshing technique based on error control is employed, which refines or coarsens the mesh in different regions by evaluating the error magnitude of each mesh element, effectively controlling the mesh size. Furthermore, a mesh generation algorithm based on triangulation is used, dividing the model into multiple triangles to generate the mesh, effectively improving the efficiency and accuracy of the simulation.

[0062] In this embodiment, the rock mechanical parameters of the region to be evaluated include: elastic modulus, Poisson's ratio, Lamé constant, cohesion, and internal friction.

[0063] In one embodiment, the rock mechanical parameters of the region to be evaluated are obtained through the following steps B1-B2:

[0064] Step B1: Based on the three-dimensional rock mechanics model in the three-dimensional geomechanical model of the reservoir, reservoir inversion is performed on the reservoir in the area to be evaluated to obtain rock mechanics parameters.

[0065] Step B2 involves adjusting the rock mechanical parameters by conducting triaxial and shear tests on core samples from the reservoir in the area to be evaluated.

[0066] Specifically, the three-dimensional rock mechanics model in the three-dimensional geomechanical model of the reservoir is used to perform reservoir inversion in the area to be evaluated, and obtain rock mechanics parameters. Triaxial tests and shear tests are then carried out on the core samples of the reservoir in the area to be evaluated to adjust the rock mechanics parameters so that the obtained rock mechanics parameters are more accurate.

[0067] Furthermore, in order to improve the accuracy of the obtained rock mechanics parameters, the rock mechanics parameters can be adjusted by conducting triaxial and shear tests on the core samples of the reservoir in the area to be evaluated using well logging parameters.

[0068] Specifically, Poisson's ratio is calculated using well logging parameters through the following expression:

[0069]

[0070] Where v represents Poisson's ratio, v p V represents the longitudinal wave velocity. s The transverse wave velocity, Δt p The longitudinal wave time difference, Δt s This indicates the transverse wave time difference.

[0071] The elastic modulus is calculated using the well logging parameters through the following expression:

[0072]

[0073] Where K represents the elastic modulus, ρ represents the formation bulk density, and v p V represents the longitudinal wave velocity. s The transverse wave velocity, Δt p The longitudinal wave time difference, Δt s This indicates the transverse wave time difference.

[0074] The Lamé constant is calculated using well logging parameters through the following expression:

[0075]

[0076] Where R is Lamé constant, ρ represents formation bulk density, and v p V represents the longitudinal wave velocity. s The transverse wave velocity, Δt p The longitudinal wave time difference, Δt s This indicates the transverse wave time difference.

[0077] Using well logging parameters, Young's modulus is calculated using the following expression:

[0078]

[0079] Where E represents Young's modulus, K represents elastic modulus, ρ represents formation bulk density, and v s V represents the transverse wave velocity. p Represents the longitudinal wave velocity, Δt p The longitudinal wave time difference, Δt s This indicates the transverse wave time difference.

[0080] The shear modulus is calculated using the well logging parameters through the following expression:

[0081]

[0082] Where G represents the shear modulus, ρ represents the formation bulk density, and v s The transverse wave velocity, Δt s This indicates the transverse wave time difference.

[0083] The uniaxial compressive strength is calculated using the well logging parameters through the following expression:

[0084] S c =E[0.008V sh +0.0045(1-V sh (6)

[0085] Among them, S c V represents uniaxial compressive strength, E represents Young's modulus, and V represents... sh Indicates the mud content.

[0086] The inherent shear strength is calculated using the well logging parameters through the following expression:

[0087]

[0088] Where C represents the inherent shear strength, S c denoted by uniaxial compressive strength, and k represents the volume compressibility coefficient.

[0089] The tensile strength of the rock is calculated using the following expression based on well logging parameters:

[0090]

[0091] Among them, S t S represents the tensile strength of rock. c It represents uniaxial compressive strength.

[0092] In one embodiment, when calculating the wellbore stress components of anisotropic formations, it is necessary to use rock mechanics parameters and a three-dimensional geomechanical model of the reservoir to extract the three-dimensional geostress distribution characteristics, and then obtain the wellbore stress components of the anisotropic formations based on the three-dimensional geostress distribution characteristics. Specifically, the steps for calculating the wellbore stress components of anisotropic formations include the following sub-steps C1-C2:

[0093] Sub-step C1: Extract the three-dimensional geostress distribution characteristics based on rock mechanics parameters and the three-dimensional geomechanical model of the reservoir.

[0094] Sub-step C2 involves performing multiple rounds of coordinate system transformation on the three-dimensional geostress distribution characteristics to obtain the wellbore stress components of the anisotropic formation in the target coordinate system.

[0095] In sub-step C1, the three-dimensional geostress distribution characteristics include: the minimum horizontal principal stress, the maximum horizontal principal stress, and the vertical stress.

[0096] Specifically, in the sub-step C1 step of extracting the three-dimensional geostress distribution characteristics, firstly, reservoir inversion is performed using the three-dimensional geostress model in the reservoir three-dimensional geomechanical model. At the same time, experimental results such as geostress test results and field low-pressure analysis are collected to constrain the magnitude of the inverted geostress. The geostress direction is constrained by paleomagnetic and wave anisotropy results, as well as imaging logging interpretation results, to obtain the three-dimensional geostress distribution characteristics. Figure 2 and Figure 3 The maximum and minimum horizontal principal stresses obtained by inversion from the three-dimensional geostress model are shown respectively.

[0097] In sub-step C2, the multi-round coordinate system transformation process involves sequentially transforming from the geodetic coordinate system to the wellbore rectangular coordinate system, and then from the wellbore rectangular coordinate system to the wellbore polar coordinate system.

[0098] Specifically, in sub-step C2, based on the reservoir's three-dimensional geomechanical model with the wellbore trajectory loaded, the three-dimensional geostress distribution characteristics, and the bedding attitude, the three-dimensional geostress distribution characteristics are transformed from the geodetic coordinate system to the wellbore rectangular coordinate system, and then the three-dimensional geostress distribution characteristics in the wellbore rectangular coordinate system are transformed to the wellbore polar coordinate system to obtain the wellbore stress components of the anisotropic formation in the wellbore polar coordinates.

[0099] The three-dimensional geostress distribution characteristics are transformed from the geodetic coordinate system to the wellbore rectangular coordinate system using the following expression:

[0100]

[0101] Where, σ x σ y σ z τ xy τ xz τ yz These represent the total stress components, σ indicates that only the real part of the result within the parentheses is taken. xx，i σ represents the normal stress in the x-direction of the x-plane caused by geostress. xx，a σ represents the normal stress in the x-direction of the x-plane caused by anisotropy. yy，i σ represents the normal stress in the y-direction of the y-plane caused by geostress. yy，a τ represents the normal stress in the y-direction of the y-plane caused by anisotropy. xy，i τ represents the shear stress in the y-direction of the x-plane caused by geostress. xy，a τ represents the normal stress in the y-direction of the x-plane caused by anisotropy. xz，i τ represents the shear stress in the z-direction of the x-plane caused by geostress. xz，a τ represents the normal stress in the z-direction of the x-plane caused by anisotropy. yz，i τ represents the shear stress in the z-direction of the y-plane caused by geostress. yz，a σ represents the normal stress in the z-direction of the y-plane caused by anisotropy. zz，i σ represents the normal stress in the z-direction of the z-plane caused by geostress. zz，a B represents the normal stress in the z-direction of the z-plane caused by anisotropy. 31 B 32 B 34 B 35 and B 36 These are elements in the compliance matrix.

[0102] Specifically, the compliance matrix is ​​expressed using the following expression:

[0103]

[0104] Where B represents the compliance matrix, E represents the elastic modulus in the isotropic surface, v represents the Poisson's ratio in the isotropic surface, E′ represents the elastic modulus in the normal direction of the isotropic surface, v′ represents the Poisson's ratio in the normal direction of the isotropic surface, and G′ represents the shear modulus of the plane perpendicular to the isotropic surface.

[0105] Specifically, ξ i Calculate using the following expression:

[0106]

[0107] Where, ξ iξ is a root of expression (11), which has 6 roots, and they are pairwise conjugate. i Let i be the three roots whose imaginary part is positive (where i = 1, 2, 3).

[0108] χ i Calculate using the following expression:

[0109]

[0110] Specifically, φ′1(z1), φ′2(z2), and φ′3(z3) are calculated using the following expressions:

[0111]

[0112] Among them, D′, E′, F′, G k Calculate using the following expressions respectively:

[0113]

[0114] The following expression is used to transform the wellbore stress components from the rectangular coordinate system to the polar coordinate system:

[0115]

[0116] Where, σ r Represents radial stress, σ x σ represents the total stress components, θ represents the wellbore angle, and σ represents the wellbore angle. y τ represents the total stress components. xy σ represents the total stress components. θ τ represents circumferential stress. rθ τ represents the shear stress in the θ direction of the r-plane. θz τ represents the shear stress in the z-direction of the θ-plane. rz σ represents the shear stress in the z-direction of the r-plane. y τ represents the total stress components. yz τ represents the total stress components. xz σ represents the total stress components. z This indicates axial stress.

[0117] Optionally, to facilitate the calculation of collapse pressure, the wellbore stress components are converted into principal stress forms using the following expression:

[0118]

[0119] Where σ1 represents the maximum principal stress, σ2 represents the intermediate principal stress, and σ θ σ represents circumferential stress. z τ represents axial stress. θzσ represents the shear stress in the z-direction of the θ-plane, σ3 represents the minimum principal stress, and σ r This represents radial stress.

[0120] Step S120: Calculate the collapse pressure under the wellbore trajectory conditions of the infill well based on the well perimeter stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir.

[0121] Based on the converted principal stress and the three-dimensional geomechanical model of the reservoir, the collapse pressure under the wellbore trajectory conditions of the infill well is calculated, and then the critical drilling mud density is obtained, so as to determine the drilling design scheme of the infill well in the area to be evaluated.

[0122] In one embodiment, Figure 4 The collapse pressure under a specific infill well trajectory is presented. When calculating the collapse pressure under the infill well trajectory conditions, the critical bottom-hole pressure of the matrix and the bottom-hole pressure at the weak surface boundary are calculated using the Mogi-Column criterion and the Jaeger weak surface criterion, respectively. The critical bottom-hole pressure of the matrix, the bottom-hole pressure at the weak surface boundary, and the reservoir pore pressure are compared, and the minimum value among the three is taken as the collapse pressure under the current infill well trajectory conditions. Specifically, step S120 includes the following sub-steps D1-D2:

[0123] In sub-step D1, the wellbore stress components of the anisotropic formation are imported into the three-dimensional geomechanical model of the reservoir. Combining the Mogi-Column criterion and the Jaeger weak surface criterion, the critical bottom-hole pressure of the matrix and the bottom-hole pressure of the weak surface are calculated.

[0124] Sub-step D2 takes the minimum value among the matrix critical bottom hole pressure, weak surface boundary bottom hole pressure, and reservoir pore pressure distribution as the collapse pressure under the current infill well trajectory conditions.

[0125] Specifically, the calculation process for collapse pressure under current infill well trajectory conditions includes:

[0126] (1) Establish the relationship between the bedding plane coordinate system and the geodetic coordinate system, and determine the angle between the maximum principal stress around the well and the normal to the bedding plane. The steps for determining the angle between the maximum principal stress around the well and the normal to the bedding plane are as follows:

[0127]

[0128] Where, β i The angle between the maximum principal stress around the well and the normal to the bedding plane is represented, n represents the direction vector of the normal to the bedding plane in the geodetic coordinate system, and N represents the direction vector of the maximum principal stress around the well in the geodetic coordinate system.

[0129] The direction vectors of the bedding plane normal in the geodetic coordinate system and the direction vectors of the maximum principal stress around the well in the geodetic coordinate system are respectively expressed by the following expressions:

[0130] n=[cosα bp sinβ bp sinα bp sinβ bq cosβ bq (20)

[0131]

[0132] Where n represents the direction vector of the bedding plane normal in the geodetic coordinate system, N represents the direction vector of the maximum principal stress around the well in the geodetic coordinate system, and α bp Indicating the tendency of bedding, β bp α represents the dip angle of the bedding planes. b Indicates wellbore tendency, β b The bedding dip angle is represented by γ, the angle between the maximum principal stress and the wellbore axis Ze is represented by θ, and the wellbore perimeter angle is represented by τ. θz σ represents the shear stress in the z-direction of the θ-plane. θ σ represents circumferential stress. z This indicates axial stress.

[0133] (2) Calculate the critical bottomhole pressure of the matrix according to the Mogi-Column criterion. The Mogi-Column criterion is expressed as follows:

[0134] τ oct =a+bσ′ m，2 (twenty three)

[0135]

[0136] Where, σ′ m，2 σ represents the effective uniform stress. oct σ' represents the octahedral shear stress, c represents the matrix cohesion, φ represents the matrix internal friction angle, a and b represent intermediate variables, σ′1 represents the first principal stress, and σ′3 represents the third principal stress.

[0137] (3) Calculate the bottomhole pressure at the weak surface boundary using the Jaeger weak surface criterion. The Jaeger weak surface criterion is expressed by the following formula:

[0138]

[0139] Among them, C w Indicates the cohesion of the bedding plane. β represents the internal friction angle of the bedding plane, and β is the angle between the normal of the weak surface of the shale and the maximum principal stress. w1 and β w2These are all critical angles at which shale bedding planes undergo slippage and failure.

[0140] (4) The minimum value among the matrix critical bottom hole pressure, weak surface boundary bottom hole pressure and reservoir pore pressure distribution is taken as the collapse pressure under the current infill well trajectory conditions.

[0141] Step S130: By adjusting the wellbore trajectory of the infill well, the collapse pressure under different infill well trajectories is formed, and the drilling design scheme of the infill well is guided based on the collapse pressure under different infill well trajectories.

[0142] Considering that the wellbore trajectory has a significant impact on wellbore stability, the three-dimensional geomechanical model of the reservoir is updated by repeatedly adjusting the wellbore trajectory of the infill well. The collapse pressure corresponding to different wellbore trajectories of the infill well is recalculated, and the collapse pressure under the optimized wellbore trajectory is used to guide the drilling design scheme of the infill well.

[0143] Optionally, Figure 5 The collapse pressure under different infill well trajectories was shown. The critical mud density under different infill well trajectories was calculated based on the collapse pressure. Based on the critical drilling mud density under different infill well trajectories, the drilling design scheme for infill wells in the evaluation area was determined.

[0144] In one embodiment, when adjusting the infill well trajectory, the inclination angle and azimuth angle in the infill well trajectory are adjusted to obtain the collapse pressure under different infill well trajectories, thereby obtaining the critical drilling mud density. Finally, the critical drilling mud density under different infill well trajectory conditions is determined to identify the drilling design scheme for the infill wells in the evaluation area. Specifically, step S130 includes the following steps S1-S3:

[0145] Step S1: Adjust the inclination angle and azimuth angle in the wellbore trajectory of the infiltrated well and update the three-dimensional geomechanical model of the reservoir.

[0146] Step S2: Based on the updated three-dimensional geomechanical model, the critical drilling mud density is obtained.

[0147] Step S3: Repeat steps S1 and S2 continuously to determine the drilling design scheme for infill wells in the area to be evaluated based on the critical drilling mud density under different infill well trajectory conditions.

[0148] In step S2, the critical drilling mud density of the infill well is calculated using the following expression:

[0149]

[0150] Among them, MW low p represents the critical drilling mud density of infill wells. cmp represents the critical bottomhole pressure of the matrix. cw This indicates that the weakly facing the boundary well bottom pressure, p p denoted by , g represents the reservoir pore pressure, g represents the gravitational acceleration, and TVD represents the actual depth of the infill well.

[0151] Optionally, Figure 6 The calculation results of collapse pressure for isotropic and anisotropic infill wells are presented, enabling the calculation of collapse pressure based on... Figure 6 To better analyze the impact of anisotropic well collapse pressure on wellbore stability.

[0152] Based on the above-described method for evaluating wellbore collapse pressure, the present invention also provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method described in any one or more of the above embodiments.

[0153] Based on the above-described method for evaluating wellbore collapse pressure in infill wells, the present invention also provides a system for evaluating wellbore collapse pressure in infill wells. This system for evaluating wellbore collapse pressure in infill wells implements the method described above.

[0154] Figure 7 This is a schematic diagram of a system for evaluating wellbore collapse pressure according to an embodiment of this application. Figure 7 As shown, the system for evaluating the life extension of oil and gas facilities according to the embodiments of the present invention includes: a well perimeter stress component calculation module 701, a collapse pressure calculation module 702, and an infill well drilling scheme generation module 703.

[0155] Specifically, the wellbore stress component calculation module 701 is implemented according to the method described in step S110 above, and is configured to calculate the wellbore stress components of anisotropic formations based on the rock mechanics parameters of the area to be evaluated and the three-dimensional geomechanical model of the reservoir loaded with the infill well trajectory; the collapse pressure calculation module 702 is implemented according to the method described in step S120 above, and is configured to calculate the collapse pressure under the infill well trajectory conditions based on the wellbore stress components of anisotropic formations and the three-dimensional geomechanical model of the reservoir; the infill well drilling scheme generation module 703 is implemented according to the method described in step S130 above, and is configured to form the collapse pressure under different infill well trajectories by adjusting the infill well trajectory, and guide the infill well drilling design scheme based on the collapse pressure under different infill well trajectories.

[0156] This invention proposes a method and system for evaluating wellbore collapse pressure in infill wells. This method and system require correction of the inverted rock mechanics parameters through laboratory experiments, thereby improving the ability to update rock mechanics parameters through a combination of experimental and numerical simulation techniques. Compared to pure numerical simulation methods, this approach offers higher accuracy and can effectively guide safe and efficient infill well drilling and subsequent production stimulation. It also considers the significant anisotropy of shale formations and its impact on wellbore stability, and designs infill well drilling schemes based on collapse pressure under different wellbore trajectories. This improves wellbore stability during infill well drilling, thereby reducing drilling accidents and enhancing the efficiency of infill well drilling.

[0157] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0158] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0159] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0160] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0161] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0162] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for evaluating wellbore collapse pressure in infill wells, characterized in that, include: Based on the rock mechanics parameters of the area to be evaluated and the three-dimensional geomechanical model of the reservoir loaded with the wellbore trajectory of the infill well, the well perimeter stress components of the anisotropic formation are calculated. Based on the wellbore stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir, the collapse pressure under the wellbore trajectory conditions of the infill well is calculated. By adjusting the wellbore trajectory of the infill well, the collapse pressure under different infill well trajectories is generated, and this is used to guide the drilling design scheme of the infill well.

2. The method according to claim 1, characterized in that, The three-dimensional geomechanical model of the reservoir is constructed using the following steps: Based on the basic measurement data of the area to be evaluated, a three-dimensional detailed geological model of the area to be evaluated is established. Based on the basic measurement data, the key properties of the reservoir are obtained using numerical simulation methods, and the key properties of the reservoir are added to the three-dimensional fine geological model to construct a reservoir property model. Based on the basic measurement data, the correspondence between reservoir properties and rock mechanical properties is analyzed, and the correspondence is added to the reservoir property model to construct a three-dimensional rock mechanical model. Based on the structural parameters and rock mechanics parameters of the area to be evaluated, a three-dimensional geostress model is constructed using a grid interaction algorithm and a finite element algorithm. Based on the three-dimensional geostress model and the three-dimensional rock mechanics model, a three-dimensional geomechanical model of the reservoir is constructed.

3. The method according to claim 2, characterized in that, The basic measurement data includes, but is not limited to, well logging parameters, well logging parameters, and seismic parameters. The step of obtaining key reservoir attributes using numerical simulation methods based on the basic measurement data of the area to be evaluated includes: Based on the earthquake parameters, the geological properties used to describe the area to be evaluated are obtained; Based on the seismic parameters and the logging parameters, the lithological spatial variation characteristics describing the area to be evaluated are obtained using the Kriging interpolation method. Based on the distribution characteristics of geological attributes and the spatial variation characteristics of lithology, the lithological distribution characteristics of the area to be evaluated are obtained; Using lithological distribution characteristics as constraints, numerical simulations were performed based on the well logging parameters to obtain key reservoir properties.

4. The method according to claim 2 or 3, characterized in that, The steps of constructing a three-dimensional geostress model based on the tectonic and rock mechanical parameters of the region to be evaluated, using the mesh interaction algorithm and the finite element algorithm, include: The structural parameters are imported into the finite element model using the finite element method, and the rock mechanics parameters are imported into the finite element model using a mesh interaction algorithm. The structural parameters include underground structure and geological structure. A three-dimensional geostress model is constructed by performing geostress simulation calculations on the finite element model with the imported structural parameters and rock mechanics parameters.

5. The method according to any one of claims 2 to 4, characterized in that, The rock mechanical parameters of the area to be evaluated are obtained through the following steps: Based on the three-dimensional rock mechanics model in the reservoir three-dimensional geomechanical model, reservoir inversion is performed on the reservoir in the area to be evaluated to obtain rock mechanics parameters; The rock mechanical parameters, including elastic modulus, Poisson's ratio, Lamé constant, cohesion, and internal friction, are adjusted by conducting triaxial and shear tests on core samples from the reservoir in the area to be evaluated.

6. The method according to any one of claims 1 to 5, characterized in that, The step of calculating the collapse pressure under infill well trajectory conditions based on the wellbore stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir includes: The wellbore stress components of the anisotropic formation are imported into the three-dimensional geomechanical model of the reservoir. The critical bottom-hole pressure of the matrix and the bottom-hole pressure of the weak surface are calculated by combining the Mogi-Column criterion and the Jaeger weak surface criterion. The minimum value among the matrix critical bottom hole pressure, the weak face boundary bottom hole pressure, and the reservoir pore pressure distribution is taken as the collapse pressure under the current infill wellbore trajectory conditions.

7. The method according to any one of claims 1 to 6, characterized in that, The steps for calculating the wellbore stress components of anisotropic formations include: Based on the rock mechanics parameters and the reservoir three-dimensional geomechanical model, the three-dimensional geostress distribution characteristics are extracted. The three-dimensional geostress distribution characteristics are subjected to multiple rounds of coordinate system transformation to obtain the wellbore stress components of anisotropic formations in the target coordinate system. The multiple rounds of coordinate system transformation are performed sequentially from the geodetic coordinate system to the wellbore rectangular coordinate system and from the wellbore rectangular coordinate system to the wellbore polar coordinate system.

8. The method according to any one of claims 1 to 7, characterized in that, The steps for guiding infill well drilling design based on the collapse pressure under different infill well trajectories include: Step S1: Adjust the inclination angle and azimuth angle in the wellbore trajectory of the infiltrated well, and update the three-dimensional geomechanical model of the reservoir; Step S2: Based on the updated three-dimensional geomechanical model, obtain the critical drilling mud density; Step S3: Repeat steps S1 and S2 continuously to determine the drilling design scheme for infill wells in the area to be evaluated based on the critical drilling mud density under different infill well trajectory conditions.

9. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method as described in any one of claims 1 to 8.

10. A system for evaluating wellbore collapse pressure in infill wells, characterized in that, include: The wellbore stress component calculation module is configured to calculate the wellbore stress components of anisotropic formations based on the rock mechanics parameters of the area to be evaluated and the three-dimensional geomechanical model of the reservoir loaded with the wellbore trajectory of the infill well. The collapse pressure calculation module is configured to calculate the collapse pressure under the wellbore trajectory conditions of the infill well based on the well perimeter stress components of the anisotropic formation and the three-dimensional geomechanical model of the reservoir. The infill well drilling scheme generation module is configured to generate collapse pressure under different infill well trajectories by adjusting the wellbore trajectory of the infill well, and to guide the infill well drilling design scheme based on this.

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