Method, system and equipment for determining drilling track of multilateral well and medium

Abstract

The invention discloses a method, a system and equipment for determining a drilling track of a multilateral borehole and a medium, and belongs to the technical field of oil and gas drilling engineering technologies. The method for determining the drilling track of the multilateral borehole comprises the steps that a target block where a main borehole is located is determined, and geomechanical parameters of the target block are obtained; calculating stress distribution information of the target block by using the branch point wall clamping finite element model; according to the stress distribution information, determining a parameter range when the wall clamping wall stress is smaller than the target layer rock fracture pressure, and according to the parameter range, determining a borehole included angle between the branch borehole and the main borehole; establishing a discrete element model of the multilateral well, and setting parameters of the discrete element model; determining the drilling direction of the multilateral well by using the discrete element model; and according to the borehole included angle and the drilling direction, the drilling track of the multilateral borehole is determined. According to the method, the drilling track of the multilateral well can be determined on the premise of ensuring the stability of the well wall, and the safety of the drilling process is improved.

Description

Technical Field

[0001] This application relates to the field of oil and gas drilling engineering technology, and in particular to a method, system, equipment and medium for determining the drilling trajectory of branch wells. Background Technology

[0002] With the continuous improvement of drilling technology, higher requirements have been placed on reservoir development, such as connecting more oil and gas reservoirs and increasing the degree of reservoir opening. Multi-branch wells are an advantageous technology to meet these requirements. The wall between the branch wellbore and the main wellbore is a high-risk area for collapse, and the stability of the branch wellbore directly affects its extension length. Both are important factors that determine the success rate of sidetracking and the continuity of subsequent operations.

[0003] In related technologies, wellbore stability mechanical models are typically used to design the drilling trajectory of branch wells. The above methods can provide a macroscopic description of the directional drilling azimuth and formation instability, but it is difficult to focus on specific reservoirs and specific wellbore sizes for detailed analysis, resulting in poor wellbore stability.

[0004] Therefore, how to determine the drilling trajectory of branch wells while ensuring wellbore stability and improving the safety of the drilling process is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a method, system, equipment, and medium for determining the drilling trajectory of branch wells, which can determine the drilling trajectory of branch wells while ensuring the stability of the wellbore, thereby improving the safety of the drilling process.

[0006] To solve the above-mentioned technical problems, this application provides a method for determining the drilling trajectory of a branch wellbore, comprising:

[0007] Determine the target block where the main wellbore is located, and obtain the geomechanical parameters of the target block;

[0008] Based on the aforementioned geomechanical parameters, a corresponding branch point wall finite element model is established for the preset profile; wherein, the preset profile is a profile in the target block whose degree of fracture development, degree of bedding development, and degree of well wall instability meet preset conditions;

[0009] The stress distribution information of the target block is calculated using the finite element model of the branch point sandwich wall; wherein, the stress distribution information includes the stress distribution of the sandwich wall under multiple preset parameter combinations, and the parameters in the preset parameter combinations include dogleg angle and the angle of the maximum horizontal principal stress;

[0010] The parameter range for when the stress in the interlayer wall is less than the fracture pressure of the target layer rock is determined based on the stress distribution information, and the wellbore angle between the branch wellbore and the main wellbore is determined based on the parameter range; wherein, the parameter range includes the dogleg range and the range of the maximum horizontal principal stress angle.

[0011] Establish a discrete element model of the branch wellbore and set the parameters of the discrete element model;

[0012] The drilling direction of the branch wellbore is determined using the discrete element model.

[0013] The drilling trajectory of the branch well is determined based on the wellbore angle and the drilling direction.

[0014] Optionally, obtaining the geomechanical parameters of the target block includes:

[0015] The target block is subjected to geological analysis to obtain the geomechanical parameters; wherein, the geomechanical parameters include the distribution of geostress, the fracture orientation of the target layer, actual drilling parameters, rock mechanical parameters, fracture surface mechanical parameters, and rock failure criteria.

[0016] Optionally, based on the aforementioned geomechanical parameters, a corresponding finite element model of the branch point wall is established for the preset profile, including:

[0017] The preset profile is selected from the target block based on the degree of fracture development, the degree of bedding development, and the degree of wellbore instability;

[0018] A two-dimensional finite element model of the branch point clamping wall is established for the preset profile, and the parameters of the finite element model of the branch point clamping wall are set according to the geomechanical parameters.

[0019] Optionally, the parameters of the discrete element model can be set, including:

[0020] Set the particle size for the discrete element model, and set the crack surface network in the discrete element model;

[0021] In the discrete element model, the microscopic parameters of the particle elements and the crack surface are set;

[0022] The discrete element model is simulated, and the microscopic parameters are adjusted based on the simulation results.

[0023] Optionally, before setting the particle size for the discrete element model and setting the network of crack surfaces in the discrete element model, the method further includes:

[0024] The size of the particle unit was obtained through rock grain size analysis.

[0025] The network location and grid size of the fracture surface are determined based on the fracture dip angle and fracture development density in the aforementioned geomechanical parameters.

[0026] Optionally, determining the drilling direction of the branch wellbore using the discrete element model includes:

[0027] The discrete element model is used to calculate the rock state of the wellbore under multiple alternative parameter combinations; wherein, the parameters in the alternative parameter combinations include fracture dip angle and fracture development density, and the rock state includes instability and force chain distribution;

[0028] The drilling direction of the branch well is determined based on the rock condition.

[0029] Optionally, determining the drilling trajectory of the branch wellbore based on the wellbore angle and the drilling direction includes:

[0030] The target location is read from the configuration file, and the drilling trajectory of the branch well is determined based on the wellbore angle, the drilling direction, and the target location.

[0031] This application also provides a drilling trajectory determination system for branch wells, the system comprising:

[0032] The parameter acquisition module is used to determine the target block where the main wellbore is located and to acquire the geomechanical parameters of the target block.

[0033] The finite element module is used to establish a corresponding branch point wall finite element model for a preset profile based on the geomechanical parameters; wherein, the preset profile is a profile in the target block whose degree of fracture development, degree of bedding development, and degree of well wall instability meet preset conditions;

[0034] The stress distribution determination module is used to calculate the stress distribution information of the target block using the finite element model of the branch point sandwich wall; wherein, the stress distribution information includes the stress distribution of the sandwich wall under multiple preset parameter combinations, and the parameters in the preset parameter combinations include dogleg angle and the angle of the maximum horizontal principal stress;

[0035] Angle determination module is used to determine the parameter range when the stress of the interlayer wall is less than the fracture pressure of the target layer rock based on the stress distribution information, and to determine the wellbore angle between the branch wellbore and the main wellbore based on the parameter range; wherein, the parameter range includes the dogleg angle range and the horizontal maximum principal stress angle range;

[0036] The discrete element model building module is used to build the discrete element model of the branch wellbore and set the parameters of the discrete element model;

[0037] The direction determination module is used to determine the drilling direction of the branch wellbore using the discrete element model;

[0038] The drilling trajectory determination module is used to determine the drilling trajectory of the branch wellbore based on the wellbore angle and the drilling direction.

[0039] This application also provides a storage medium storing a computer program thereon, which, when executed, implements the steps of the above-described method for determining the drilling trajectory of a branch wellbore.

[0040] This application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor invokes the computer program in the memory to implement the steps of the above-described method for determining the drilling trajectory of a branch wellbore.

[0041] This application provides a method for determining the drilling trajectory of a branch wellbore. The method determines the geomechanical parameters of the target block where the main wellbore is located, and establishes a corresponding branch point wall finite element model based on the geomechanical parameters for a preset profile. This allows for the calculation of stress distribution information in the target block using the branch point wall finite element model. Based on the stress distribution information, this application determines the parameter ranges for dogleg stress and the angle between the horizontal maximum principal stresses, and then determines the wellbore angle between the branch wellbore and the main wellbore based on these parameter ranges. This application also utilizes the discrete element model of the branch wellbore to determine its drilling direction, and then combines the wellbore angle and drilling direction to determine the drilling trajectory of the branch wellbore. By comprehensively collecting and analyzing geomechanical parameters, this application ensures the realism and accuracy of the modeling, enabling the determination of the branch wellbore's drilling trajectory while maintaining wellbore stability, thus improving the safety of the drilling process. This application also provides a branch wellbore drilling trajectory determination system, a storage medium, and an electronic device, all possessing the aforementioned beneficial effects, which will not be elaborated upon further here. Attached Figure Description

[0042] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A flowchart illustrating a method for determining the drilling trajectory of a branch wellbore, provided as an embodiment of this application;

[0044] Figure 2 This is a schematic diagram of the frequency distribution of the dip angle of a natural crack provided in an embodiment of this application;

[0045] Figure 3 This is a schematic diagram of the maximum stress under different side-drilling dogleg conditions provided in an embodiment of this application;

[0046] Figure 4 This application provides a schematic diagram of the maximum stress under different angles between the borehole and the formation's maximum horizontal principal stress direction;

[0047] Figure 5 A comparison diagram of triaxial compressive stress-strain curves from numerical simulation and indoor test (confining pressure 60MPa) provided for embodiments of this application;

[0048] Figure 6 This is a schematic diagram comparing the shear stress curves of the first numerical simulation and the indoor direct shear test provided in the embodiments of this application;

[0049] Figure 7 This is a schematic diagram comparing the second type of numerical simulation and the shear stress curve of the indoor direct shear test provided in the embodiments of this application;

[0050] Figure 8 This is a total displacement cloud map of a drilling model with different fracture angles after drilling, considering the effects of fluid, provided in an embodiment of this application. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] Please see below. Figure 1 , Figure 1 A flowchart illustrating a method for determining the drilling trajectory of a branch wellbore, provided as an embodiment of this application.

[0053] Specific steps may include:

[0054] S101: Determine the target block where the main wellbore is located, and obtain the geomechanical parameters of the target block;

[0055] This embodiment can be applied to electronic devices with modeling and numerical calculation functions. Through the relevant operations in S101-S107, the drilling trajectory of the branch wells can be obtained. The main well is the first well drilled from the surface, and it can provide the starting point for subsequent branch wells during the drilling process.

[0056] After determining the target block where the main wellbore is located, the geomechanical parameters of that area can be obtained. These geomechanical parameters may include the distribution of in-situ stress, the orientation of fractures in the target layer, actual drilling parameters, the mechanical parameters of the corresponding rock and fracture surfaces, and any one or a combination of rock failure criteria.

[0057] S102: Establish a finite element model of the branch point wall for the preset profile based on the aforementioned geomechanical parameters;

[0058] This step involves selecting a pre-defined profile that reflects the main contradictions, and then establishing a corresponding finite element model of the branch point wall for the pre-defined profile based on geomechanical parameters. The aforementioned pre-defined profile is one in the target block where the degree of fracture development, bedding development, and wellbore instability meet pre-defined conditions.

[0059] Specifically, this step selects a preset profile that meets the preset conditions and uses the finite element method (FEM) to establish a finite element model of the branch point clamping wall. In this embodiment, the geometric parameters of the branch point clamping wall finite element model can also be set according to geomechanical parameters. This branch point clamping wall finite element model helps to analyze the mechanical behavior of the wellbore under different conditions, ensure wellbore stability, and thus improve the safety and efficiency of the drilling process.

[0060] S103: Calculate the stress distribution information of the target block using the finite element model of the branch point wall;

[0061] This step utilizes a finite element model of the branch-point clamping wall to calculate the stress distribution information of the target block, enabling detailed analysis of the well wall's mechanical behavior under different conditions through numerical simulation. The stress distribution information includes the clamping wall stress distribution under multiple preset parameter combinations, where parameters include dogleg stress and the angle of the maximum horizontal principal stress.

[0062] Specifically, in this embodiment, different dogleg angles and horizontal maximum principal stress angles can be set in the finite element model of the branch point clamping wall to simulate the stress distribution under various possible wellbore trajectories and geostress conditions. Through the above simulation, the stress distribution of the clamping wall under different parameter combinations can be obtained, thereby identifying which combinations can make the clamping wall stress lower than the rock fracture pressure.

[0063] S104: Determine the parameter range when the stress of the interlayer wall is less than the rock fracture pressure of the target layer based on the stress distribution information, and determine the wellbore angle between the branch wellbore and the main wellbore based on the parameter range;

[0064] In this step, the parameter range when the stress in the interlayer wall is less than the fracture pressure of the target rock layer can be determined based on the stress distribution information. This parameter range includes the dogleg range and the range of the horizontal maximum principal stress angle.

[0065] By analyzing the stress distribution under different preset parameter combinations, combinations where the stress in the branch wellbore is lower than the rock fracture pressure are selected. The dogleg angle and the angle between the maximum horizontal principal stresses in these combinations constitute the optimal parameter range. Based on this, this embodiment can determine the wellbore angle between the branch wellbore and the main wellbore, ensuring the stability of the wellbore during construction.

[0066] The aforementioned wellbore angle refers to the angle between the axis of the branch wellbore and the axis of the main wellbore when the branch wellbore branches off from the main wellbore. This embodiment uses a finite element model to calculate the stress distribution under different parameter combinations, thereby determining the optimal wellbore angle.

[0067] S105: Establish the discrete element model of the branch wellbore and set the parameters of the discrete element model;

[0068] This step involves establishing a discrete element model (DEM) of the branch wellbore and setting its parameters to simulate the interactions between rock particles in detail. By setting these parameters, the DEM can more accurately reflect the fracture distribution and mechanical behavior in the actual formation, providing reliable data support for subsequent drilling direction optimization.

[0069] S106: Determine the drilling direction of the branch well using the discrete element model;

[0070] This step utilizes the discrete element model to simulate wellbore rock instability and force chain distribution under different fracture dip angles and development densities, thereby determining the drilling direction of the branch wellbore. This method allows for the selection of the optimal drilling direction based on the stability of the wellbore rock under various conditions. This embodiment ensures that the drilling direction minimizes the risk of wellbore instability, thus improving the safety and efficiency of the drilling process.

[0071] S107: Determine the drilling trajectory of the branch wellbore based on the wellbore angle and the drilling direction.

[0072] In this step, the drilling trajectory of the branch wellbore can be determined based on the wellbore angle and drilling direction. The drilling trajectory of the branch wellbore is determined by combining these two parameters, thus enabling the branch wellbore to smoothly reach the target location and maintain wellbore stability.

[0073] This embodiment provides a method for determining the drilling trajectory of a branch wellbore. The method determines the geomechanical parameters of the target block where the main wellbore is located, and establishes a corresponding branch point wall finite element model based on the geomechanical parameters for a preset profile. This allows for the calculation of stress distribution information in the target block using the branch point wall finite element model. This embodiment determines the parameter ranges for dogleg stress and the angle between the horizontal maximum principal stresses based on the stress distribution information, and then determines the wellbore angle between the branch wellbore and the main wellbore based on these parameter ranges. This embodiment also uses the discrete element model of the branch wellbore to determine its drilling direction, and then combines the wellbore angle and drilling direction to determine the drilling trajectory of the branch wellbore. This embodiment ensures the realism and accuracy of the modeling by comprehensively collecting and analyzing geomechanical parameters, enabling the determination of the branch wellbore's drilling trajectory while ensuring wellbore stability, thus improving the safety of the drilling process.

[0074] As for Figure 1 A further description of the corresponding embodiment is that the geomechanical parameters of the target block can be obtained by performing geological analysis on the target block to obtain the geomechanical parameters; wherein, the geomechanical parameters include the distribution of geostress, the fracture orientation of the target layer, actual drilling parameters, rock mechanical parameters, fracture surface mechanical parameters, and rock failure criteria.

[0075] Specifically, this embodiment can conduct geological surveys and on-site drilling investigations of the target block to obtain information on the distribution of in-situ stress, the orientation of fractures in the target layer, and actual drilling engineering parameters; this embodiment can collect rock samples from the target layer and obtain the mechanical parameters of the corresponding layer rock and fracture surface through conventional triaxial tests, direct shear tests, and fracture surface friction tests; this embodiment can also analyze the stress-strain relationship during rock deformation to determine rock failure criteria.

[0076] As for Figure 1 In a further description of the corresponding embodiment, this embodiment can establish a branch point sandwich wall finite element model in the following way: select the preset profile from the target block according to the degree of fracture development, the degree of bedding development and the degree of well wall instability; establish a two-dimensional branch point sandwich wall finite element model for the preset profile, and set the parameters of the branch point sandwich wall finite element model according to the geomechanical parameters.

[0077] Specifically, this embodiment simplifies the three-dimensional wellbore mechanics problem into a two-dimensional mechanical model. It selects a cross-section reflecting the main contradiction, establishes a finite element model of the branch point wall, sets the radius and inclination angle of the main wellbore and branch wellbore, sets the principal stress at the wellbore wall, and calculates the stress distribution of the wall under different dogleg inclinations of the side-drilling sections and different horizontal maximum principal stress angles. This embodiment can obtain the dogleg range and the horizontal maximum principal stress angle range where the wall stress is less than the fracture pressure of the target layer rock, and derive optimization suggestions based on the stress variation law. Combined with the target point location, it determines the wellbore angle of the drilling trajectory.

[0078] As for Figure 1 In a further description of the corresponding embodiment, the parameters of the discrete element model can be set in the following manner: setting the particle size of the discrete element model and setting a network of crack surfaces in the discrete element model; setting the mesoscopic parameters of the particle size and crack surfaces in the discrete element model; simulating the discrete element model and adjusting the mesoscopic parameters according to the simulation results. Mesoscopic parameters are parameters of an object or system that lie between the macroscopic and microscopic scales, and their scale range is typically within 10^64 ohms. -3 m~10 -9 m.

[0079] Furthermore, before setting the particle size for the discrete element model and setting the network of fracture surfaces in the discrete element model, the particle size can be obtained through rock grain size analysis; the network position and mesh size of the fracture surfaces can be determined based on the fracture dip angle and fracture development density in the geomechanical parameters.

[0080] As for Figure 1 Further description of the corresponding embodiment: This embodiment determines the drilling direction of the branch wellbore in the following way: The discrete element model is used to calculate the rock state of the wellbore under multiple alternative parameter combinations; the drilling direction of the branch wellbore is determined based on the rock state. The parameters in the alternative parameter combinations include fracture dip angle and fracture development density, and the rock state includes instability and force chain distribution. Due to the anisotropy of the formation, this embodiment uses a discrete element model for modeling the branch wellbore. The size of the particle unit is set according to the target layer rock grain size, a specified fracture mesh is generated, and the micro-cementation parameters between particle units and the micro-mechanical parameters of the fracture surface are set. This embodiment can simulate triaxial mechanical tests and direct shear tests under formation conditions, compare the simulation results with the test results, adjust the model's micro-parameters, set the radius and dip angle of the branch wellbore, set the stress state around the well, establish a formation model of the branch wellbore, calculate the instability and force chain distribution of the wellbore under different fracture dip angles and development densities, and select a suitable drilling direction based on the instability.

[0081] As for Figure 1 As further described in the corresponding embodiment, this embodiment can optimize the design of the branch well trajectory based on the branch point and the drilling trajectory of the branch wellbore obtained from numerical simulation analysis, combined with the target point location. Specifically, this embodiment can read the target point location from the configuration file and determine the drilling trajectory of the branch wellbore according to the wellbore angle, the drilling direction, and the target point location.

[0082] As a feasible implementation method, the micromechanical parameters of the rock include: rock cohesion, internal friction angle, compressive strength, shear strength and elastic modulus; the micromechanical strength parameters of the crack surface include: friction coefficient and shear strength.

[0083] As a feasible implementation method, the rock matrix model can adopt a parallel bond model. The microscopic bonding parameters between particle units include particle size, contact modulus, particle stiffness ratio, parallel bond installation spacing, parallel bond stiffness ratio, parallel bond expansion coefficient, particle friction coefficient, parallel bond cohesion, parallel bond tensile strength, and parallel bond friction angle. The crack surface model adopts a smooth joint model. The microscopic strength parameters of the crack surface include smooth joint normal stiffness, smooth joint tangential stiffness, smooth joint friction coefficient, smooth joint tensile strength, smooth joint cohesion, smooth joint friction angle, and smooth joint shear strength.

[0084] As a feasible implementation method, the size of the particle unit in the target layer rock grain size setting in this embodiment is obtained from rock grain size experimental analysis, which can realistically represent the state of rock particles; the fracture mesh generated in this embodiment is set according to the fracture dip angle and development obtained from geological survey, so as to improve the realism of the well perimeter formation model.

[0085] As a feasible implementation method, this embodiment can simulate triaxial mechanical tests and direct shear tests under formation conditions, comparing the slope and peak value of the triaxial compressive stress-strain curves of rocks with different fracture dip angles with the simulation results. By comparing the failure modes and elastoplastic deformation of the model and rock samples, and adjusting the micro-parameters of the model, the deformation characteristics of the model can be made to match the experimental results, thus better reflecting the mechanical properties of the target rock layer.

[0086] As a feasible implementation method, the stress state around the well includes: when the branch wellbore is a horizontal section, the principal stress around the well is the overlying rock stress σ. v Maximum horizontal ground stress σ H Horizontal minimum ground stress σ h The pressure P of the liquid column inside the wellbore m At the same time, the formation pore pressure P must be considered. p When the branch wellbore is an inclined section, it is necessary to use coordinate transformation formulas to convert the principal stress at the well perimeter into the principal stress at the inclined well wall in a rectangular coordinate system (x, y, z).

[0087] The process described in the above embodiments is illustrated below through examples in practical applications.

[0088] Wellbore trajectory optimization design is a crucial step in multi-branch well drilling, and its impact on wellbore stability must be fully considered. Improper trajectory design can lead to low drilling efficiency, difficulties in casing installation, and missed targets. Therefore, reasonable trajectory optimization design is a key guarantee for the safe and efficient development of oil and gas reservoirs. In designing the drilling trajectory for branch wells, the quality of the branch wellbore is a crucial factor in determining the quality of the development channel for untapped reserves. It is essential to consider both the stability of the sidetracking point's wall and the stability of the branch wellbore itself, thereby improving the extension capacity of the branch section. Currently, there is no optimization design method that can simultaneously address all of these aspects.

[0089] This embodiment provides a branch well trajectory optimization design scheme based on wellbore stability. This scheme utilizes experimental testing to obtain rock mechanics parameters and analyzes the stability of the wall and branch wellbore through numerical simulation, clearly and intuitively determining a safe branch well trajectory. Specifically, this embodiment mainly addresses the problem of high risk of wall and branch wellbore instability during sidetracking of branch wells. It establishes models of the wall and branch wellbore using rock mechanics parameters and wellbore dimensions, and analyzes wellbore stability under different conditions through numerical simulation to obtain appropriate well inclination azimuth and dogleg, thereby ensuring wellbore stability in all drilling directions determined by the trajectory optimization design.

[0090] The branch well trajectory optimization design method based on wellbore stability provided in this embodiment includes the following steps:

[0091] Step 1: Conduct geological surveys and on-site drilling in the target area to obtain information on the distribution of in-situ stress, the orientation of fractures in the target layer, and the drilling parameters; collect rock samples from the target layer, and obtain the mechanical parameters of the rock and fracture surfaces in the corresponding layers through conventional triaxial tests, direct shear tests, and fracture surface friction tests; analyze the stress-strain relationship during rock deformation and determine the rock failure criteria.

[0092] Please refer to Tables 1 and 2, which show the frequency of natural fracture dip angle distribution and formation stress in a certain block as measured in actual measurements.

[0093] Table 1. Geological Stress Tables for Block Strata

[0094]

[0095] In this embodiment, eight rock samples from this block were selected and subjected to conventional triaxial tests, direct shear tests, and fracture surface friction tests. The test results are shown in Tables 2, 3, and 4. The rock strength variations with the dip angles of the two natural fractures conform to the Mohr-Coulomb strength criterion.

[0096] Table 2 Results of Conventional Triaxial Compression Test

[0097]

[0098] Table 3 Direct Shear Test Table (Tested under axial pressure of 10MPa)

[0099]

[0100] Table 4. Results of Friction Coefficient Test

[0101]

[0102] Step 2: Simplify the three-dimensional wellbore mechanics problem into a two-dimensional mechanical model, select the profile that reflects the main contradiction, establish a finite element model of the branch point wall, set the radius and inclination angle of the main wellbore and the branch wellbore respectively, set the principal stress at the well wall, and calculate the stress distribution of the wall under different doglegs of the side drilling section and different horizontal maximum principal stress angles.

[0103] Please see Figure 2 , Figure 2 This is a schematic diagram of the frequency distribution of natural crack dip angles provided in an embodiment of this application. The diagram shows the frequency distribution of natural crack dip angles at 10° and 20°.

[0104] Please see Figure 3 , Figure 3 This is a schematic diagram of the maximum stress under different side-drilling dogleg conditions provided in an embodiment of this application. The diagram shows the correspondence between the maximum Mises stress (MPa) and the dogleg degree (° / 30m).

[0105] Please see Figure 4 , Figure 4 This application provides a schematic diagram of the maximum stress under different angles between the borehole and the formation's maximum horizontal principal stress direction. The diagram shows the correspondence between the maximum Mises stress (MPa) and the maximum principal stress and the borehole angle (° / 30m).

[0106] This embodiment can establish a soil layer of 12m×12m×3m, with a main wellbore of Φ165.mm (well inclination 30°). A Φ149.2mm upper branch is drilled using doglegs of 12° / 30m, 15° / 30m, and 18° / 30m respectively, and a Φ165.1mm lower branch is drilled using doglegs of 5° / 30m, 8° / 30m, and 12° / 30m for descending inclination. The dogleg angles for the main wellbore (lower branch) are 6° / 30m, 8° / 30m, 12° / 30m, 15° / 30m, 18° / 30m, and 20° / 30m respectively, and the dogleg angles for the branch wellbore (upper branch) are 6° / 30m, 8° / 30m, 12° / 30m, 15° / 30m, 18° / 30m, and 20° / 30m respectively.

[0107] The stress distribution of the interlayer wall was calculated under the conditions of dogleg angles of 6° / 30m, 8° / 30m, 12° / 30m, 15° / 30m, 18° / 30m, and 20° / 30m in the upper branch side drilling section. Figure 3 As shown, with the increase of the dogleg angle in the sidetracked section, the maximum stress value at the branch point of the sidetracked branch well decreases, that is, the stress concentration phenomenon weakens, and the stability of the sidewall is enhanced. The stress distribution of the sidewall was calculated under the condition that the angle between the main wellbore direction and the direction of the maximum principal stress in the ground is 0°, 10°, 20°, 30°, 45°, 60°, and 90°. Figure 4 As shown, as the included angle increases, the maximum stress value at the branch point of the side-drilled branch well increases, that is, the stress concentration phenomenon intensifies, and the stability of the sidewall weakens.

[0108] Step 3: Obtain the dogleg range where the stress in the interlayer wall is less than the fracture pressure of the target layer rock and the range of the horizontal maximum principal stress angle. Based on the stress change law, derive optimization suggestions and determine the wellbore angle of the drilling trajectory in combination with the target point location.

[0109] Step 4: Due to the anisotropy of the formation, the modeling of the branch wellbore uses a discrete element model. The size of the particle unit is set according to the rock grain size of the target layer, and a specified fracture mesh is generated. The micro-cementation parameters between particle units and the micro-mechanical parameters of the fracture surface are set. First, triaxial mechanical tests and direct shear tests under formation conditions are simulated. The simulation results are compared with the test results, and the micro-parameters of the model are adjusted. The radius and dip angle of the branch wellbore are set, the stress state around the well is set, and the formation model of the branch wellbore is established. The instability of the wellbore rock and the force chain distribution under different fracture dip angles and development densities are calculated respectively. The appropriate drilling direction is selected according to the instability.

[0110] Based on the drilling and development method of a horizontal well, the numerical model uses a longitudinal section of the formation as the simulation sample, with the overlying strata above and the strata at the same burial depth on the left and right. Natural fractures in the formation significantly affect its stability. To study the stability of strata with natural fractures, a corresponding numerical model is established. A parallel bond model is selected for the rock matrix, and a smooth joint model is selected for the fractures.

[0111] Please see Figure 5 , Figure 5 This is a comparison chart of triaxial compressive stress-strain curves obtained from numerical simulation and indoor testing (confining pressure 60 MPa) provided in an embodiment of this application. The horizontal axis represents strain / %, and the vertical axis represents differential stress / MPa. The chart shows the curves at 0° (numerical simulation), 0° (indoor testing), 90° (numerical simulation), and 90° (indoor testing).

[0112] Please see Figure 6 , Figure 6 This is a schematic diagram comparing the shear stress curves of the first numerical simulation and the indoor direct shear test provided in the embodiments of this application. The horizontal axis represents the shear displacement / 10. -1 mm, with the vertical axis representing shear stress / MPa. The figure shows the curves at 0° in the numerical simulation and 0° in the laboratory test.

[0113] Please see Figure 7 , Figure 7 This is a schematic diagram comparing the shear stress curves of the second numerical simulation and the indoor direct shear test provided in the embodiments of this application. The horizontal axis represents the shear displacement / 10. -1 mm, with the vertical axis representing shear stress / MPa. The figure shows the curves of the numerical simulation at 90° and the experimental results at 90° from the indoor test.

[0114] Keeping the vertical stress at 90 MPa and the maximum horizontal principal stress at 95 MPa constant, and based on the distribution of weak surface angles in the shale formation at a certain location, wellbore models with four different fracture angles (0°, 10°, 20°, and 30°) were set up. Drilling calculations were then performed on the models, and the results are as follows: Figure 8 As shown, Figure 8 This application provides a total displacement cloud map of a drilling model with different fracture angles after considering fluid effects. The color gradients in the map represent the magnitude of the displacement, and E-02, E-03, and E-04 represent scaling factors per unit length (representing multiplication by 10 to the power of -2, -3, and -4, respectively). The wellbore displacement is minimal at a fracture angle of 0°, approximately 16.9 mm, while the displacement is maximum at a fracture angle of 10°, approximately 21.8 mm. Therefore, the angle of the weak structural face has a significant impact on the displacement and deformation area of ​​shale particles. Encountering a 10° fracture during drilling has a more significant impact on the displacement of rock particles, leading to a greater risk of wellbore instability.

[0115] Step 5: Based on the branch points and drilling trajectories of the branch wells obtained from numerical simulation analysis, and combined with the target point location, complete the optimized design of the branch well trajectory.

[0116] According to an exemplary embodiment of the branch well trajectory optimization design method based on wellbore stability, the rock micromechanical parameters may include: rock cohesion, internal friction angle, compressive strength, shear strength, and elastic modulus; the micromechanical strength parameters of the fracture surface include: friction coefficient and shear strength.

[0117] As an exemplary embodiment of the branch well trajectory optimization design method based on wellbore stability, the rock matrix model adopts a parallel bonding model, and the micro-cementing parameters between particle units include particle size, contact modulus, particle stiffness ratio, parallel bonding installation spacing, parallel bonding stiffness ratio, parallel bonding expansion coefficient, particle friction coefficient, parallel bonding cohesion, parallel bonding tensile strength, and parallel bonding friction angle; the fracture surface model adopts a smooth joint model, and the micro-strength parameters of the fracture surface include smooth joint normal stiffness, smooth joint tangential stiffness, smooth joint friction coefficient, smooth joint tensile strength, smooth joint cohesion, smooth joint friction angle, and smooth joint shear strength.

[0118] As an exemplary embodiment of the branch well trajectory optimization design method based on wellbore stability, the size of the target layer rock grain size setting particle unit is obtained from rock grain size experimental analysis, which can realistically represent the state of rock particles; the generated fracture mesh is set according to the fracture dip angle and development obtained from geological survey, thereby improving the realism of the well perimeter formation model.

[0119] According to an exemplary embodiment of the branch well trajectory optimization design method based on wellbore stability, the stress state around the well includes: when the branch wellbore is a horizontal section, the principal stress around the well is the overburden rock stress σ. v Maximum horizontal ground stress σ H Horizontal minimum ground stress σ h The pressure P of the liquid column inside the wellbore m At the same time, the formation pore pressure P must be considered. p .

[0120] When the branch wellbore is an inclined section, the principal stress at the well perimeter needs to be calculated using the coordinate transformation formula, which is as follows:

[0121] ;

[0122] This represents the normal stress component parallel to the x-axis on the x-plane. This represents the normal stress component parallel to the y-axis on the x-plane. This represents the normal stress component parallel to the z-axis on the x-plane. This represents the normal stress component parallel to the x-axis on the y-plane. This represents the normal stress component parallel to the y-axis on the y-plane. This represents the normal stress component parallel to the z-axis on the y-plane. This represents the normal stress component parallel to the x-axis on the z-plane. This represents the normal stress component parallel to the y-axis on the z-plane. This represents the normal stress component parallel to the z-axis on the z-plane. This represents the coordinate transformation coefficient of the inclined wellbore, and T represents the transpose.

[0123] Convert to a Cartesian coordinate system (x, y, z). The principal stresses at the inclined shaft wall are expressed as:

[0124] ;

[0125] ;

[0126] ;

[0127] In the above formula, Indicates radial stress in the wellbore. Indicates radial stress in the wellbore. This represents the permeability coefficient (0 when the well wall is impermeable, and 1 when the well wall is permeable). Indicates porosity. Indicates the pressure of the liquid column. Indicates the effective stress coefficient. Indicates the circumferential stress of the well wall. Indicates the drilling fluid column pressure. This indicates axial force applied to the well wall;

[0128] ;

[0129] ;

[0130] ;

[0131] In the formula, X, Y, Z, A, B, C, D, E, F, G, H, J, and K1 all represent preset parameters, and their meanings are as follows:

[0132]

[0133] In the above formula, α represents the well inclination angle, and β represents the azimuth angle. θ represents the static Poisson's ratio, and θ represents the angle between the coordinate system of the inclined shaft section and the rectangular coordinate system.

[0134] As an exemplary embodiment of the branch well trajectory optimization design method based on wellbore stability, the triaxial mechanical test and direct shear test under simulated formation conditions, the triaxial compressive stress-strain curves of rocks with different fracture dip angles are compared with the slope and peak value of the simulation results, the failure mode and elastoplastic deformation of the model and rock sample are compared, and the micro-parameters of the model are adjusted so that the deformation characteristics of the model are consistent with the test results, and the mechanical properties of the target layer rock are better reflected.

[0135] This application also provides a drilling trajectory determination system for branch wells, comprising:

[0136] The parameter acquisition module is used to determine the target block where the main wellbore is located and to acquire the geomechanical parameters of the target block.

[0137] The finite element module is used to establish a corresponding branch point wall finite element model for a preset profile based on the geomechanical parameters; wherein, the preset profile is a profile in the target block whose degree of fracture development, degree of bedding development, and degree of well wall instability meet preset conditions;

[0138] The stress distribution determination module is used to calculate the stress distribution information of the target block using the finite element model of the branch point sandwich wall; wherein, the stress distribution information includes the stress distribution of the sandwich wall under multiple preset parameter combinations, and the parameters in the preset parameter combinations include dogleg angle and the angle of the maximum horizontal principal stress;

[0139] Angle determination module is used to determine the parameter range when the stress of the interlayer wall is less than the fracture pressure of the target layer rock based on the stress distribution information, and to determine the wellbore angle between the branch wellbore and the main wellbore based on the parameter range; wherein, the parameter range includes the dogleg angle range and the horizontal maximum principal stress angle range;

[0140] The discrete element model building module is used to build the discrete element model of the branch wellbore and set the parameters of the discrete element model;

[0141] The direction determination module is used to determine the drilling direction of the branch wellbore using the discrete element model;

[0142] The drilling trajectory determination module is used to determine the drilling trajectory of the branch wellbore based on the wellbore angle and the drilling direction.

[0143] This embodiment determines the geomechanical parameters of the target block where the main wellbore is located, and establishes a corresponding branch point wall finite element model based on the geomechanical parameters for a preset profile, so as to calculate the stress distribution information of the target block according to the branch point wall finite element model. This embodiment determines the parameter range of dogleg and the angle between the maximum horizontal principal stresses based on the stress distribution information, and then determines the wellbore angle between the branch wellbore and the main wellbore based on the parameter range. This embodiment also uses the discrete element model of the branch wellbore to determine the drilling direction of the branch wellbore, and then combines the wellbore angle and drilling direction to determine the drilling trajectory of the branch wellbore. This embodiment ensures the realism and accuracy of the modeling by comprehensively collecting and analyzing geomechanical parameters, and can determine the drilling trajectory of the branch wellbore while ensuring wellbore stability, thus improving the safety of the drilling process.

[0144] Furthermore, the process by which the parameter acquisition module acquires the geomechanical parameters of the target block includes: performing geological analysis on the target block to obtain the geomechanical parameters; wherein, the geomechanical parameters include the distribution of geostress, the fracture orientation of the target layer, actual drilling engineering parameters, rock mechanical parameters, fracture surface mechanical parameters, and rock failure criteria.

[0145] Furthermore, the process of establishing a finite element model of the branch point wall for the preset profile based on the geomechanical parameters includes: selecting the preset profile from the target block based on the degree of fracture development, bedding development, and wellbore instability; establishing a two-dimensional finite element model of the branch point wall for the preset profile; and setting the parameters of the finite element model of the branch point wall based on the geomechanical parameters.

[0146] Furthermore, the process of setting the parameters of the discrete element model in the discrete element model establishment module includes: setting the particle size for the discrete element model and setting the network of the crack surface in the discrete element model; setting the micro-parameters of the particle and crack surface in the discrete element model; simulating the discrete element model and adjusting the micro-parameters according to the simulation results.

[0147] Furthermore, it also includes:

[0148] The parameter setting module is used to obtain the particle size through rock grain size analysis before setting the particle size for the discrete element model and setting the network of fracture surfaces in the discrete element model; it is also used to determine the network position and mesh size of the fracture surface based on the fracture dip angle and fracture development density in the geomechanical parameters.

[0149] Furthermore, the process by which the direction determination module determines the drilling direction of the branch wellbore using the discrete element model includes: calculating the rock state of the wellbore rock under multiple alternative parameter combinations using the discrete element model; wherein, the parameters in the alternative parameter combinations include fracture dip angle and fracture development density, and the rock state includes instability and force chain distribution; and determining the drilling direction of the branch wellbore based on the rock state.

[0150] Furthermore, the process by which the drilling trajectory determination module determines the drilling trajectory of the branch wellbore based on the wellbore angle and the drilling direction includes: reading the target point position from the configuration file, and determining the drilling trajectory of the branch wellbore based on the wellbore angle, the drilling direction, and the target point position.

[0151] Since the embodiments of the system part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the system part, and they will not be repeated here.

[0152] This application also provides a storage medium on which a computer program is stored, which, when executed, can perform the steps provided in the above embodiments. The storage medium may include various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0153] This application also provides an electronic device that may include a memory and a processor. The memory stores a computer program, and when the processor calls the computer program in the memory, it can implement the steps provided in the above embodiments. Of course, the electronic device may also include various network interfaces, power supplies, and other components.

[0154] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0155] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for determining the drilling trajectory of a branch wellbore, characterized in that, The method comprises the following steps: determining a target block where a main borehole is located, and obtaining geomechanical parameters of the target block; establishing a corresponding branch point sandwich wall finite element model for a preset profile according to the geomechanical parameters; wherein the preset profile is a profile in the target block where the fracture development degree, the bedding development degree and the wellbore instability degree meet preset conditions; calculating stress distribution information of the target block by using the branch point sandwich wall finite element model; wherein the stress distribution information includes sandwich wall stress distribution situations under a plurality of preset parameter combinations, and the parameters in the preset parameter combinations include dogleg severity and horizontal maximum principal stress angle; determining a parameter range when the sandwich wall stress is less than the rock breakdown pressure of a target layer according to the stress distribution information, and determining a borehole angle between a branch borehole and the main borehole according to the parameter range; wherein the parameter range includes a dogleg severity range and a horizontal maximum principal stress angle range; establishing a discrete element model of the branch borehole, and setting parameters of the discrete element model; determining a drilling direction of the branch borehole by using the discrete element model; determining a drilling trajectory of the branch borehole according to the borehole angle and the drilling direction.

2. The method of claim 1, wherein, The method for obtaining the geomechanical parameters of the target block comprises the following steps: obtaining the geomechanical parameters by performing a geological analysis on the target block; wherein the geomechanical parameters include geostress distribution, fracture occurrence of the target layer, actual drilling engineering parameters, rock mechanics parameters, fracture surface mechanics parameters and rock failure criteria.

3. The method of claim 1, wherein, The method for establishing a corresponding branch point sandwich wall finite element model for a preset profile according to the geomechanical parameters comprises the following steps: selecting the preset profile from the target block according to the fracture development degree, the bedding development degree and the wellbore instability degree; establishing a two-dimensional branch point sandwich wall finite element model for the preset profile, and setting parameters of the branch point sandwich wall finite element model according to the geomechanical parameters.

4. The method of claim 1, wherein, The method for setting parameters of the discrete element model comprises the following steps: setting a particle element size for the discrete element model, and setting a network of fracture surfaces in the discrete element model; setting mesoscopic parameters of particle elements and fracture surfaces in the discrete element model; simulating the discrete element model, and adjusting the mesoscopic parameters according to the simulation results.

5. The method of claim 4, wherein, Before setting the particle element size for the discrete element model and setting the network of fracture surfaces in the discrete element model, the method further comprises the following steps: obtaining the particle element size by performing a rock granularity experiment analysis; determining the network position and grid size of the fracture surfaces according to the fracture dip angle and the fracture development density in the geomechanical parameters.

6. The method of claim 1, wherein, The method for determining the drilling direction of the branch borehole by using the discrete element model comprises the following steps: calculating rock states of the wellbore rock under a plurality of alternative parameter combinations by using the discrete element model; wherein the parameters in the alternative parameter combinations include the fracture dip angle and the fracture development density, and the rock states include instability conditions and force chain distributions; determining the drilling direction of the branch borehole according to the rock states.

7. The method of claim 1, wherein, The method for determining the drilling trajectory of the branch borehole according to the borehole angle and the drilling direction comprises the following steps: reading a target point position from a configuration file, determining a drilling trajectory of the branch wellbore according to the wellbore included angle, the drilling direction and the target point position.

8. A drilling trajectory determination system for a branched wellbore, characterized by, The method comprises the steps of: a parameter acquisition module configured to determine a target block in which a main wellbore is located and acquire geomechanical parameters of the target block; a finite element module establishment module configured to establish a corresponding branch point sandwich wall finite element model for a preset profile according to the geomechanical parameters; wherein the preset profile is a profile in which a fracture development degree, a bedding development degree and a wellbore instability degree of the target block meet preset conditions; a stress distribution determination module configured to calculate stress distribution information of the target block by using the branch point sandwich wall finite element model; wherein the stress distribution information comprises sandwich wall stress distribution situations under a plurality of preset parameter combinations, and parameters in the preset parameter combinations comprise dogleg severity and a horizontal maximum principal stress included angle; an included angle determination module configured to determine a parameter range in which a sandwich wall stress is less than a rock breakdown pressure of a target layer according to the stress distribution information, and determine a wellbore included angle between a branch wellbore and the main wellbore according to the parameter range; wherein the parameter range comprises a dogleg severity range and a horizontal maximum principal stress included angle range; a discrete element model establishment module configured to establish a discrete element model of the branch wellbore and set parameters of the discrete element model; a direction determination module configured to determine a drilling direction of the branch wellbore by using the discrete element model; a drilling trajectory determination module configured to determine a drilling trajectory of the branch wellbore according to the wellbore included angle and the drilling direction.

9. An electronic device, comprising: The method comprises the steps of:

10. A storage medium, characterized by a memory and a processor, the memory storing a computer program, and the processor calling the computer program in the memory to realize the steps of the method for determining a drilling trajectory of a branch wellbore according to any one of claims 1 to 7. The storage medium stores computer executable instructions, and the computer executable instructions are loaded and executed by the processor to realize the steps of the method for determining a drilling trajectory of a branch wellbore according to any one of claims 1 to 7.

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