Regulation and control method and system for hole wall instability of horizontal drill hole in high ground stress environment

Abstract

The invention provides a regulation and control method and system for hole wall instability of a horizontal drill hole in a high ground stress environment, and belongs to the technical field of horizontal drilling. The method comprises the steps that a high ground stress hole wall instability model based on elastic-plastic damage mechanics is established, and a high ground stress correction coefficient, a dynamic damage variable and a multi-field coupling equation are introduced into the model; model parameters are corrected in real time based on measurement while drilling data, and the hole wall stability is dynamically predicted; according to the prediction result, the model prediction error can be greatly reduced through the method, the progressive damage process of the rock mass in the high ground stress environment can be accurately described, and the technical problem of inaccurate prediction of a traditional static model is solved. By correcting model parameters in real time and dynamically adjusting a wall protection strategy, the hole wall instability accident rate is reduced, and the drilling operation safety is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of horizontal drilling technology, and particularly relates to a method and system for controlling the instability of the borehole wall in a horizontal borehole under high ground stress environment. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] As oil and gas exploration and development extends into deeper formations, horizontal drilling operations under high geostress environments face increasingly severe borehole stability issues. In deep formations, the interaction of high geostress, complex geological structures, and harsh downhole environments leads to frequent borehole collapses, diameter reductions, and stuck pipe incidents during drilling, severely impacting drilling efficiency and operational safety.

[0004] Traditional borehole wall protection techniques have limited effectiveness under high stress conditions and may exacerbate formation damage due to excessive fracturing. Existing research is largely based on static elasticity theory or empirical formulations, failing to fully reveal the dynamic evolution mechanism and multi-field coupling effects of borehole wall instability under high in-situ stress. For example, in terms of traditional mechanical models, most studies establish static strength theoretical models based on the Mohr-Coulomb or Hoek-Brown criteria, but do not consider the nonlinear deformation of the rock mass caused by drilling fluid infiltration and pore pressure, as well as the cumulative damage effect. Regarding wall protection techniques, existing technologies mainly rely on passive wall protection measures, which have a regulatory lag and primarily use polymers and nanoparticles as plugging agents. However, under high stress, the bonding strength between the material and the formation interface is insufficient, making it susceptible to shear failure and leading to wall protection failure. In numerical simulation, existing studies mostly use the finite element method for borehole wall stability analysis. The finite element method often assumes the formation is a homogeneous continuum, neglecting the influence of natural fractures and anisotropy of in-situ stress, and failing to fully quantify the chemical-mechanical coupling mechanism in the interaction between the flushing fluid and the formation. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a method and system for controlling borehole wall instability in horizontal boreholes under high geostress conditions. It comprehensively considers the nonlinear deformation, damage evolution, and multi-field coupling effects of rock masses under high geostress conditions, and proposes an active control strategy based on this to improve borehole wall stability and reduce borehole risks.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a method for controlling the instability of the borehole wall in a horizontal borehole under high ground stress conditions; A method for controlling borehole wall instability under high ground stress conditions includes: A high-stress hole wall instability model based on elastoplastic damage mechanics is established. The model incorporates a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations. Real-time correction of model parameters based on drilling measurement data to dynamically predict borehole wall stability; Based on the prediction results, the stability of the borehole wall can be precisely controlled through the optimization of flushing fluid, the optimization of borehole structure, and active support technology.

[0007] As a further technical solution, the high ground stress correction coefficient is used to reflect the nonlinear strengthening effect of confining pressure on rock mass strength, as shown below:

[0008] in, This is a correction factor for high ground stress. For the minimum principal stress, Peak intensity is a material constant.

[0009] As a further technical solution, the dynamic damage variable is defined using the effective elastic modulus method, as shown below:

[0010] in, As a damage variable, Given the current damage modulus, This is the initial lossless modulus.

[0011] As a further technical solution, the multi-field coupling equations include stress field control equations, seepage field control equations, and chemical field coupling equations.

[0012] As a further technical solution, the flushing fluid optimization includes adding modified silica nanoparticles to the flushing fluid to seal microfractures; and adjusting the viscosity and density of the flushing fluid in real time according to the formation pressure gradient and damage variables.

[0013] As a further technical solution, the optimization of the hole structure includes: The optimal wellbore inclination angle and azimuth angle are determined by finite element analysis, so that the angle between the wellbore axis and the direction of the maximum horizontal principal stress is less than a set threshold.

[0014] As a further technical solution, active support technology includes inserting an expandable casing before drilling to a high-stress layer. After expansion, the casing fits tightly against the borehole wall to provide radial support force, and the fractured zone is consolidated by injecting high-strength chemical slurry.

[0015] A second aspect of the present invention provides a control system for the instability of the borehole wall in a horizontal borehole under high ground stress conditions.

[0016] A control system for horizontal borehole wall instability under high ground stress conditions includes: The model building module is configured to: establish a high-stress hole wall instability model based on elastoplastic damage mechanics, wherein the model incorporates a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations; The stability prediction module is configured to: dynamically predict borehole stability by correcting model parameters in real time based on drilling measurement data; The control and execution module is configured to achieve precise control of the orifice wall stability based on the prediction results through flushing fluid optimization, orifice structure optimization, and active support technology.

[0017] A third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps of a method for controlling instability of the borehole wall in a high-stress environment as described in the first aspect of the present invention.

[0018] The fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the method for controlling the instability of the borehole wall in a high ground stress environment as described in the first aspect of the present invention.

[0019] The above one or more technical solutions have the following beneficial effects: (1) This invention establishes a high-stress borehole wall instability model based on elastoplastic damage mechanics, and innovatively introduces a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations, which significantly reduces the model prediction error. According to the dynamic damage evolution equation, the progressive failure process of rock mass under high stress environment can be accurately described, solving the technical problem of inaccurate prediction by traditional static models.

[0020] (2) This invention dynamically adjusts the wall protection strategy by correcting model parameters in real time based on drilling measurement data. Compared with the traditional passive response method, it reduces the rate of borehole instability accidents and significantly improves the safety of drilling operations. By establishing a fully coupled model that includes stress field, seepage field and chemical field, the targeted nature of wall protection measures is improved.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1This is a flowchart of the method in the first embodiment.

[0024] Figure 2 This is a system structure diagram of the second embodiment. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0027] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0028] Example 1 This embodiment discloses a method for controlling the instability of the borehole wall in a horizontal borehole under high ground stress conditions; like Figure 1 As shown, a method for controlling borehole wall instability under high ground stress conditions includes: Step S1: Establish a high-stress hole wall instability model based on elastoplastic damage mechanics. The model introduces a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations. Step S2: Based on the drilling measurement data, the model parameters are corrected in real time to dynamically predict the borehole wall stability; Step S3: Based on the prediction results, the stability of the borehole wall is precisely controlled through flushing fluid optimization, borehole structure optimization, and active support technology.

[0029] Specifically, it also includes the following: By introducing a high ground stress correction coefficient, dynamic damage variables, and multi-field coupling equations, an elastoplastic damage constitutive relation containing the high ground stress correction coefficient is constructed. Combined with the damage variables and damage rate equations, a multi-field coupling model of stress field, seepage field, and chemical field is constructed.

[0030] The high ground stress correction factor is used to reflect the nonlinear strengthening effect of confining pressure on rock mass strength. In this embodiment, a triaxial compression test is performed on the rock sample. Rock cores from the target strata are collected, processed into standard cylindrical specimens, and confining pressure is applied on a servo-controlled triaxial testing machine. The range covers actual ground stress, and the load is applied at a constant strain rate until failure, recording the peak strength. , fitting and The power function relationship:

[0031] in, denoted as uniaxial compressive strength, and a and b as fitting parameters.

[0032] Subsequently, a high ground stress correction factor was defined. This is the ratio of strength under confining pressure to uniaxial strength:

[0033] make That is, we get:

[0034] in, For the minimum principal stress, The uniaxial compressive strength of the rock mass. and n, material constants.

[0035] By comprehensively considering flushing fluid penetration, dynamic changes in pore pressure, and time effects, a multi-field coupling instability criterion is established.

[0036] Furthermore, the damage variable is defined using the effective elastic modulus method. :

[0037] in, Given the current damage modulus, This is the initial lossless modulus.

[0038] Fatigue loading tests were conducted by applying cyclic loading to the rock sample, pausing after every 100 cycles, and measuring the ultrasonic wave velocity. calculate ,Establish Differential form of the number of iterations N:

[0039] Fitting using power-law form:

[0040] in , is the reference stress (usually taken as ). ).

[0041] Convert the number of loops N to time t ( , Substituting the load frequency into the borehole vibration frequency yields the dynamic damage equation:

[0042] in, For equivalent stress, The reference stress is A, m, and k, which are damage parameters.

[0043] The multi-field coupled equations, which include coupled stress, seepage, and chemical fields, describe the effect of flushing fluid infiltration on pore wall stability. The stress field governing equation uses a modified Biot equation to describe the porous elastic medium.

[0044] Where C is the damage-dependent stiffness tensor ( ), For Biot coefficient, It is a displacement vector.

[0045] The flow field governing equation is used to account for permeability changes caused by damage. ):

[0046] in, For fluid viscosity, The damage-permeability coefficient.

[0047] Chemical field coupling is achieved by adding a chemical osmotic pressure term. :

[0048] in, , The concentration difference between drilling fluid and pore water is solved using the ion diffusion equation.

[0049] Furthermore, the Galerkin method is used to discretize the coupled equations using the finite element method, forming a global matrix:

[0050] Where K is the stiffness matrix, Q is the coupling matrix, and H is the penetration matrix.

[0051] In step S2, the model parameters are corrected in real time based on the drilling measurement data to dynamically predict the borehole wall stability; Real-time data acquisition of in-situ stress, rock mechanics parameters, drill string vibration frequency, and flushing fluid parameters using logging-while-drilling equipment, followed by Kalman filtering preprocessing, dynamically corrects the high in-situ stress correction factor. and damage variables And combined with damage evolution equation Predict damage trends; substitute the modified parameters into the coupled control equations to solve the stress field, seepage field and chemical field equations, calculate the stability coefficient, and perform graded control to achieve dynamic prediction of pore wall stability.

[0052] Step S3: Based on the prediction results, the stability of the borehole wall is precisely controlled through flushing fluid optimization, borehole structure optimization, and active support technology.

[0053] Specifically, flushing fluid optimization balances formation pressure and reduces permeation damage by dynamically adjusting the flushing fluid density, viscosity, and plugging agent content. This includes adding 1%-3% modified silica nanoparticles to the flushing fluid to seal microfractures; and adjusting the flushing fluid according to the formation pressure gradient. and damage variables Adjust the viscosity and density of the rinsing fluid in real time.

[0054] Hole structure optimization optimizes the hole trajectory based on stress distribution to avoid high stress concentration areas, specifically including: The optimal wellbore inclination and azimuth angles are determined using finite element analysis, such that the angle between the wellbore axis and the direction of maximum horizontal principal stress is [missing information]. .

[0055] Active support technology uses expandable casing or chemically consolidated materials to enhance the local bearing capacity of the borehole wall. Specifically, it includes: inserting expandable casing before drilling to the high stress layer, which expands and fits tightly against the borehole wall to provide radial support; and injecting high-strength chemical slurry to consolidate the fractured zone.

[0056] Example 2 This embodiment discloses a control system for horizontal borehole wall instability under high ground stress environment; like Figure 2 As shown, a control system for horizontal borehole wall instability under high ground stress conditions includes: The model building module is configured to: establish a high-stress hole wall instability model based on elastoplastic damage mechanics, wherein the model incorporates a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations; The stability prediction module is configured to: dynamically predict borehole stability by correcting model parameters in real time based on drilling measurement data; The control and execution module is configured to achieve precise control of the orifice wall stability based on the prediction results through flushing fluid optimization, orifice structure optimization, and active support technology.

[0057] Example 3 The purpose of this embodiment is to provide a computer-readable storage medium.

[0058] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the method for controlling the instability of the borehole wall in a high ground stress environment as described in Example 1.

[0059] Example 4 The purpose of this embodiment is to provide an electronic device.

[0060] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the control method for horizontal borehole wall instability under high ground stress environment as described in Embodiment 1.

[0061] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0062] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0063] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for controlling borehole wall instability under high ground stress conditions, characterized in that, include: A high-stress hole wall instability model based on elastoplastic damage mechanics is established. The model incorporates a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations. Real-time correction of model parameters based on drilling measurement data to dynamically predict borehole wall stability; Based on the prediction results, the stability of the borehole wall can be precisely controlled through the optimization of flushing fluid, the optimization of borehole structure, and active support technology.

2. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, The high ground stress correction factor is used to reflect the nonlinear strengthening effect of confining pressure on rock mass strength, as shown below: in, This is a correction factor for high ground stress. For the minimum principal stress, Peak intensity is a material constant.

3. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, The dynamic damage variable is defined using the effective elastic modulus method, as shown below: in, As a damage variable, Given the current damage modulus, This is the initial lossless modulus.

4. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, The multi-field coupling equations include stress field control equations, seepage field control equations, and chemical field coupling equations.

5. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, The flushing fluid optimization includes adding modified silica nanoparticles to the flushing fluid to seal microfractures; and adjusting the viscosity and density of the flushing fluid in real time according to the formation pressure gradient and damage variables.

6. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, The optimization of the hole structure includes: The optimal wellbore inclination angle and azimuth angle are determined by finite element analysis, so that the angle between the wellbore axis and the direction of the maximum horizontal principal stress is less than a set threshold.

7. The method for controlling borehole wall instability under high ground stress environment as described in claim 1, characterized in that, Active support technology involves inserting an expandable casing before drilling into a high-stress zone. After expansion, the casing fits tightly against the borehole wall, providing radial support, and consolidating the fractured zone by injecting high-strength chemical grout.

8. A control system for borehole wall instability in a horizontal borehole under high ground stress conditions, characterized in that: include: The model building module is configured to: establish a high-stress hole wall instability model based on elastoplastic damage mechanics, wherein the model incorporates a high-stress correction coefficient, dynamic damage variables, and multi-field coupling equations; The stability prediction module is configured to: dynamically predict borehole stability by correcting model parameters in real time based on drilling measurement data; The control and execution module is configured to achieve precise control of the orifice wall stability based on the prediction results through flushing fluid optimization, orifice structure optimization, and active support technology.

9. A computer-readable storage medium having a program stored thereon, characterized in that, When executed by the processor, the program implements the steps in the control method for horizontal borehole wall instability under high ground stress environment as described in any one of claims 1-7.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the control method for horizontal borehole wall instability under high ground stress environment as described in any one of claims 1-7.

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