Reservoir stability evaluation method in ultrahigh pressure gas well production process

Abstract

The invention provides a reservoir stability evaluation method in the production process of an ultrahigh-pressure gas well, and belongs to the technical field of oil-gas field development well completion. According to the method, well wall stability analysis is carried out by using logging information such as natural gamma, sound waves, density, resistivity and well diameter of a target reservoir section, data such as rock mechanics parameters, ground stress and three stratum pressures of a stratum are calculated, and data fitting correction is carried out in combination with an indoor rock mechanics parameter experiment; and finally, based on a finite element perforation completion well wall instability evaluation model, effectively evaluating the well wall stability of the abnormal high-pressure gas reservoir by adjusting different types of parameters. The well wall stability can be maintained, reservoir sand production is effectively controlled, and then normal production of a target gas well is guided.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development and completion, and in particular to a method for evaluating reservoir stability during the production process of an ultra-high pressure gas well. Background Art

[0002] In the process of oil and gas reservoir exploration and development, it is common to encounter complex underground conditions caused by wellbore instability, such as wellbore collapse, diameter reduction, leakage, and sanding of reservoirs. When the physical properties of the Qingshuihe Formation of the target reservoir gas well are poor, with low porosity and low permeability, it is a typical gas-bearing reservoir. Actual drilling data show that this layer is an abnormally high-temperature, high-pressure reservoir with complex and changeable formation conditions, strong tectonic stress and poor wellbore stability. Wellbore instability becomes an inevitable problem, and accidents such as overflow, wellbore collapse, and well leakage occur from time to time.

[0003] For abnormally high-pressure fractured gas reservoirs, natural completion methods can no longer meet the requirements. Currently, perforation completion is the mainstream completion method. Drawing on the perforation completion process in the early Tarim block, large-scale blockage of holes occurred in the late production period. Under stable production conditions, the production pressure difference of a single hole was infinitely magnified, and the wellbore at the perforated hole was broken, unstable and sanded. Therefore, perforation completion has extremely high requirements for wellbore support. It is urgent to start from the actual needs of the mine, consider the effects of high temperature, high pressure and ultra-depth on wellbore instability and reservoir sanding, and establish a wellbore instability evaluation method based on abnormally high-pressure gas reservoirs to guide the efficient development of the same type of oil and gas reservoirs in the target block gas wells.

[0004] The existing technology has at least the following deficiencies:

[0005] 1. Existing technologies mostly focus on the evaluation of wellbore stability during drilling, but do not involve the evaluation of reservoir stability during production, which has certain limitations;

[0006] 2. Existing technologies are mainly aimed at conventional oil and gas wells, and there are few reservoir stability evaluations for ultra-deep, high-temperature and high-pressure gas wells, which are not of reference value;

[0007] 3. The existing technology mainly remains in the theoretical stage and cannot be applied in actual production. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the present invention proposes a wellbore instability evaluation method based on abnormally high-pressure gas reservoirs, and uses natural gamma, acoustic wave, density, resistivity, wellbore diameter and other logging data of the target reservoir section to carry out wellbore stability analysis, calculates the rock mechanics parameters, geostress and formation three pressures and other data of the formation, combines indoor rock mechanics parameter experiments, and performs data fitting and correction. Finally, based on the finite element perforation completion wellbore instability evaluation model, the wellbore stability of the abnormally high-pressure gas reservoir is effectively evaluated by adjusting different types of parameters (considering the influence of formation pressure attenuation, geostress changes, reservoir parameters, perforation parameters, etc.). In view of the lack of current methods for evaluating wellbore instability during perforation completion of abnormally high-pressure gas reservoirs, the present invention has innovated methods and established a method for evaluating wellbore stability during the production process of ultra-high-pressure gas wells. Aiming at ultra-deep, abnormally high-temperature and high-pressure reservoirs, in order to effectively prevent and avoid wellbore damage caused by abnormal formation conditions, the critical production pressure difference of ultra-high-pressure gas wells under variable perforation parameters in multiple production stages is predicted, and the determination of a reasonable production system for gas wells is guided. The stability of deep, high-temperature and high-pressure gas well reservoirs can be accurately evaluated, and the actual critical production pressure difference of the perforation section of the target reservoir can be calculated to maintain wellbore stability, effectively control sand production from the reservoir, and further guide the normal production of the target gas well.

[0009] The present invention provides a method for evaluating reservoir stability during the production process of an ultra-high pressure gas well, comprising the following steps:

[0010] Step S1: Obtain rock samples of the target reservoir section, conduct rock mechanics parameter experiments and geostress experiments, and obtain static rock mechanics parameters and reservoir geostress magnitude;

[0011] Step S2: preprocessing the target reservoir section logging data, and obtaining a dynamic rock mechanics parameter profile and a geostress parameter profile based on the preprocessed target reservoir section logging data;

[0012] Step S3: Correct the static rock mechanical parameters and geostress values ​​obtained from the rock mechanical parameter experiment and geostress experiment in step S1, and combine the dynamic rock mechanical parameter profile and geostress parameter profile obtained in step S2 to obtain effective rock mechanical parameters, and then obtain a dynamic and static rock mechanical parameter fitting relationship map;

[0013] Step S4: combining the dynamic and static rock mechanics parameter fitting relationship map obtained in step S3 and the target well drilling parameter inversion to obtain the maximum horizontal principal stress parameter;

[0014] Step S5: Establish a perforation and completion finite element model of the target gas well, determine the critical sand production pressure difference of the high-pressure gas well under the full life cycle of the rock based on the effective rock mechanics parameters and ground stress parameters, and determine the stability of the reservoir during the production of the ultra-high-pressure gas well based on the critical sand production pressure difference of the high-pressure gas well. The full life cycle refers to the entire process of the target gas well from the start of production to the pressure decay to the point where production cannot be carried out, which can be several years to more than ten years.

[0015] Preferably, in step S5, in the established perforation completion finite element model of the target gas well, effective rock mechanics parameters and geostress parameters are imported to simulate the geostress variation law in different perforation schemes under different formation pressures within a preset time period, analyze the influence of formation pressure, production pressure difference and perforation parameters on the wellbore stability of the high-pressure gas well, determine the critical sanding pressure difference of the high-pressure gas well under the whole life cycle, and determine the stability of the reservoir during the production of the ultra-high-pressure gas well according to the critical sanding pressure difference of the high-pressure gas well. First, a perforation completion finite element model is established. When setting the initial conditions, the control variable method is used to artificially set the initial stress field parameters according to the changes in the geostress field to achieve simulations of different stress fields; secondly, the stress field size is consistent and the perforation parameters remain unchanged to change the formation pressure size, which can be achieved within the software; similarly, under different combination conditions, the corresponding modification of parameters can achieve the goal, and the changes in the geostress field are reflected in the final output results.

[0016] Preferably, the rock mechanics parameter experiments include Brazilian splitting, longitudinal and shear wave continuous scanning experiments and triaxial compression tests.

[0017] Preferably, the tensile strength is obtained through the Paris splitting test; the longitudinal wave data, transverse wave data and dynamic Poisson's ratio are obtained through the longitudinal and transverse wave continuous scanning test; and the static Poisson's ratio, static elastic modulus, compressive strength and cohesion are obtained through the triaxial compression test.

[0018] Preferably, the geostress experiment is an acoustic emission Kessel effect experiment, and the magnitude of the geostress is predicted by the acoustic emission Kessel effect experiment.

[0019] Preferably, in step S2, the logging data of the target reservoir section are fitted and the lithology is divided to obtain the acoustic cancellation, wellbore cancellation, resistivity cancellation, gamma curve and density curve, and then obtain the dynamic rock mechanics parameter profile and the ground stress parameter profile.

[0020] Preferably, the preset time period in step S5 is more than 10 years.

[0021] Preferably, in step S2, geostress analysis is performed based on GMI software.

[0022] Preferably, in step S2, the Model Builder module in the drilling optimization design software is used to calculate the dynamic rock mechanics parameter profile and the geostress parameter profile.

[0023] Preferably, in step S4, based on the SFIB module in the GMI software, the maximum horizontal principal stress parameters are inverted in combination with the effective rock mechanics parameters obtained in step S3 and the target well drilling parameters. The maximum horizontal principal stress is obtained by inversion with the help of the geostress software. Inversion represents a process of using the software. The effective rock mechanics parameters, including cohesion, compressive strength, minimum horizontal principal stress and other parameters, are input into the software window, and then run to limit the maximum horizontal principal stress parameters through the accurate uniaxial compressive strength and minimum horizontal principal stress.

[0024] Preferably, establishing the target gas well perforation completion model specifically includes the following steps:

[0025] Based on finite element software, the perforation completion model of the target gas well is constructed, which mainly includes three parts: perforation casing, cement ring, and formation model; each part defines different properties according to reservoir and component parameters. The input of the model is mainly reflected in the setting of boundary and load conditions, and the output is mainly based on the stress size of the simulation results.

[0026] The specific input includes the setting of the original ground stress field, the assignment of formation pressure, the setting of casing perforation parameters, etc., which are implemented in different windows of the software. Under different input conditions, the stress cloud map is finally obtained and compared with the original rock compressive strength for case analysis.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The present invention predicts the stress field variation law of the target reservoir in the past ten years through indoor experiments, and provides basic parameters for the evaluation of wellbore stability in different production stages in the later stage;

[0029] 2. The present invention uses geological modeling software to correct and modify mechanical parameters, and then performs inversion calculation of the maximum horizontal principal stress to obtain complete geostress parameters, thereby achieving the unification of experimental results and simulation calculation results;

[0030] 3. According to the actual formation conditions and based on the high-pressure gas well completion method, the present invention establishes a perforation completion finite element model. After the perforation completion finite element evaluation is completed, it is mainly composed of three parts: formation, cement ring, and perforation casing. In different production stages of the gas well, the ground stress and formation pressure are changing. In order to ensure that the reservoir stability evaluation at different times is more accurate, the parameter size is adjusted at all times. Only by changing the perforation parameters, reservoir parameters, and the size of the original ground stress field (all implemented in the software), and then simulating and calculating the stress cloud map under different conditions, the obtained stress size is compared with the original rock uniaxial compressive strength, so as to evaluate the reservoir stability during the production process;

[0031] 4. The present invention considers the influence of the change of formation stress field during the production process on the stability of the reservoir, and simulates the high temperature and high pressure working conditions indoors through the Kessel test, thereby obtaining accurate rock mechanical parameters and ground stress parameters of the target block, providing a basis for the subsequent reservoir stability evaluation, and can test the size of the original ground stress field. By changing the size of the confining pressure, the change of the stress field in different production stages can be predicted, ensuring that the evaluation result is more accurate;

[0032] 5. The present invention takes into account the influence of high temperature and high pressure on reservoir parameters and establishes a perforation completion reservoir stability evaluation model. Compared with the prior art, which mainly studies conventional oil and gas wells, it is more in line with the actual production situation of the mine.

[0033] 6. The present invention forms a reservoir stability evaluation method during the production of ultra-high pressure gas wells, which integrates indoor experiments and software modeling to construct a high-pressure gas well reservoir stability evaluation method, achieves method innovation, solves the difficult problem faced by the reservoir stability evaluation of abnormally high temperature and high pressure gas reservoirs during the completion process, realizes the innovation of evaluation methods and design means, makes up for the shortcomings and deficiencies of the high temperature and high pressure gas well reservoir stability evaluation method, ensures the efficient production of the target reservoir gas well, and provides wellbore stability support for the subsequent completion parameter optimization design. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flow chart of a method for evaluating reservoir stability during the production of an ultra-high pressure gas well according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of an indoor rock loading and acoustic emission monitoring system according to an embodiment of the present invention;

[0036] Figure 3 A diagram showing a simulation calculation result based on ModelBuilder logging data according to an embodiment of the present invention;

[0037] Figure 4 A schematic diagram of GMI-BSFI maximum horizontal principal stress inversion according to an embodiment of the present invention;

[0038] Figure 5 It is a schematic diagram of a finite element perforation completion wellbore instability evaluation model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] The present invention provides a method for evaluating reservoir stability during the production process of an ultra-high pressure gas well, comprising the following steps:

[0041] Step S1: Obtain rock samples of the target reservoir section, conduct rock mechanics parameter experiments and geostress experiments, and obtain static rock mechanics parameters and reservoir geostress magnitude;

[0042] Step S2: preprocessing the target reservoir section logging data, and obtaining a dynamic rock mechanics parameter profile and a geostress parameter profile based on the preprocessed target reservoir section logging data;

[0043] Step S3: Correct the static rock mechanical parameters and geostress values ​​obtained from the rock mechanical parameter experiment and geostress experiment in step S1, and combine the dynamic rock mechanical parameter profile and geostress parameter profile obtained in step S2 to obtain effective rock mechanical parameters, and then obtain a dynamic and static rock mechanical parameter fitting relationship map;

[0044] Step S4: combining the dynamic and static rock mechanics parameter fitting relationship map obtained in step S3 and the target well drilling parameter inversion to obtain the maximum horizontal principal stress parameter;

[0045] Step S5: Establish a perforation and completion finite element model of the target gas well, determine the critical sand production pressure difference of the high-pressure gas well under the full life cycle of the rock based on the effective rock mechanics parameters and ground stress parameters, and determine the stability of the reservoir during the production of the ultra-high-pressure gas well based on the critical sand production pressure difference of the high-pressure gas well. The full life cycle refers to the entire process of the target gas well from the start of production to the pressure decay to the point where production cannot be carried out, which can be several years to more than ten years.

[0046] According to a specific implementation scheme of the present invention, in step S5, in the established target gas well perforation completion finite element model, effective rock mechanics parameters and geostress parameters are imported to simulate the geostress variation law in different perforation schemes under different formation pressures within a preset time period, analyze the influence of formation pressure, production pressure difference and perforation parameters on the wellbore stability of high-pressure gas wells, determine the critical sanding pressure difference of high-pressure gas wells under the whole life cycle, and determine the stability of the reservoir during the production of ultra-high-pressure gas wells according to the critical sanding pressure difference of high-pressure gas wells. First, a perforation completion finite element model is established. When setting the initial conditions, the control variable method is used to artificially set the initial stress field parameters according to the changes in the geostress field to achieve simulations of different stress fields; secondly, the stress field size is consistent and the perforation parameters remain unchanged to change the formation pressure size, which can be achieved within the software; similarly, under different combination conditions, the corresponding modification of parameters can achieve the goal, and the changes in the geostress field are reflected in the final output results.

[0047] According to a specific embodiment of the present invention, the rock mechanics parameter experiment includes Brazilian splitting, longitudinal and shear wave continuous scanning experiment and triaxial compression test.

[0048] According to a specific embodiment of the present invention, the tensile strength is obtained through the Paris splitting test; the longitudinal wave data, transverse wave data and dynamic Poisson's ratio are obtained through the longitudinal and transverse wave continuous scanning experiment; the static Poisson's ratio, static elastic modulus, compressive strength and cohesion are obtained through the triaxial compression test.

[0049] According to a specific embodiment of the present invention, the geostress experiment is an acoustic emission Kessel effect experiment, and the magnitude of the geostress is predicted by the acoustic emission Kessel effect experiment.

[0050] According to a specific implementation scheme of the present invention, in step S2, the logging data of the target reservoir section are fitted and the lithology is divided to obtain the acoustic cancellation, wellbore cancellation, resistivity cancellation, gamma curve and density curve, and then obtain the dynamic rock mechanics parameter profile and the ground stress parameter profile.

[0051] According to a specific embodiment of the present invention, the preset time period in step S5 is more than 10 years.

[0052] According to a specific implementation of the present invention, in step S2, geostress analysis is performed based on GMI software.

[0053] According to a specific implementation of the present invention, in step S2, the ModelBuilder module in the drilling optimization design software is used to calculate the dynamic rock mechanics parameter profile and the geostress parameter profile.

[0054] According to a specific embodiment of the present invention, in step S4, based on the SFIB module in the GMI software, the effective rock mechanical parameters obtained in step S3 and the target well drilling parameters are inverted to obtain the maximum horizontal principal stress parameters. The maximum horizontal principal stress is obtained by inversion with the help of the geostress software. Inversion represents a process of using the software. The effective rock mechanical parameters, including cohesion, compressive strength, minimum horizontal principal stress and other parameters, are input in the software window, and then run to limit the maximum horizontal principal stress parameters through the accurate uniaxial compressive strength and minimum horizontal principal stress.

[0055] According to a specific embodiment of the present invention, establishing a target gas well perforation completion model specifically includes the following steps:

[0056] Based on finite element software, the perforation completion model of the target gas well is constructed, which mainly includes three parts: perforation casing, cement ring, and formation model; each part defines different properties according to reservoir and component parameters. The input of the model is mainly reflected in the setting of boundary and load conditions, and the output is mainly based on the stress size of the simulation results.

[0057] The specific input includes the setting of the original ground stress field, the assignment of formation pressure, the setting of casing perforation parameters, etc., which are implemented in different windows of the software. Under different input conditions, the stress cloud map is finally obtained and compared with the original rock compressive strength for case analysis.

[0058] Example 1

[0059] According to a specific embodiment of the present invention, the reservoir stability evaluation method during the production process of an ultra-high pressure gas well of the present invention is described in detail below.

[0060] The present invention provides a method for evaluating reservoir stability during the production process of an ultra-high pressure gas well, comprising the following steps:

[0061] Step S1: Obtain rock samples of the target reservoir section, conduct rock mechanics parameter experiments and geostress experiments, and obtain static rock mechanics parameters and reservoir geostress magnitude;

[0062] Step S2: preprocessing the target reservoir section logging data, and obtaining a dynamic rock mechanics parameter profile and a geostress parameter profile based on the preprocessed target reservoir section logging data;

[0063] Step S3: Correct the static rock mechanical parameters and geostress values ​​obtained from the rock mechanical parameter experiment and geostress experiment in step S1, and combine the dynamic rock mechanical parameter profile and geostress parameter profile obtained in step S2 to obtain effective rock mechanical parameters, and then obtain a dynamic and static rock mechanical parameter fitting relationship map;

[0064] Step S4: combining the dynamic and static rock mechanics parameter fitting relationship map obtained in step S3 and the target well drilling parameter inversion to obtain the maximum horizontal principal stress parameter;

[0065] Step S5: Establish a perforation and completion finite element model of the target gas well, determine the critical sand production pressure difference of the high-pressure gas well under the full life cycle of the rock based on the effective rock mechanics parameters and ground stress parameters, and determine the stability of the reservoir during the production of the ultra-high-pressure gas well based on the critical sand production pressure difference of the high-pressure gas well. The full life cycle refers to the entire process of the target gas well from the start of production to the pressure decay to the point where production cannot be carried out, which can be several years to more than ten years.

[0066] Among them, in step S5, in the established target gas well perforation completion finite element model, effective rock mechanics parameters and ground stress parameters are imported to simulate the ground stress variation law in different perforation schemes under different formation pressures within a preset time period, analyze the influence of formation pressure, production pressure difference and perforation parameters on the wellbore stability of high-pressure gas wells, determine the critical sanding pressure difference of high-pressure gas wells under the whole life cycle, and determine the stability of the reservoir during the production of ultra-high-pressure gas wells according to the critical sanding pressure difference of high-pressure gas wells. First, a perforation completion finite element model is established. When setting the initial conditions, the control variable method is used to artificially set the initial stress field parameters according to the changes in the ground stress field to achieve different stress field simulations; secondly, the stress field size is consistent and the perforation parameters remain unchanged to change the formation pressure size, which can be achieved within the software; similarly, under different combination conditions, the corresponding modification of parameters can achieve the goal, and the changes in the ground stress field are reflected in the final output results.

[0067] Among them, rock mechanics parameter experiments include Brazilian splitting, longitudinal and shear wave continuous scanning experiments and triaxial compression tests.

[0068] Among them, the tensile strength is obtained through the Paris splitting test; the longitudinal wave data, transverse wave data and dynamic Poisson's ratio are obtained through the longitudinal and transverse wave continuous scanning experiment; the static Poisson's ratio, static elastic modulus, compressive strength and cohesion are obtained through the triaxial compression test.

[0069] Among them, the ground stress experiment is an acoustic emission Kessel effect experiment, and the magnitude of ground stress is predicted through the acoustic emission Kessel effect experiment.

[0070] Among them, in step S2, the logging data of the target reservoir section are fitted and the lithology is divided to obtain the acoustic wave cancellation, well diameter cancellation, resistivity cancellation, gamma curve and density curve, and then the dynamic rock mechanics parameter profile and the ground stress parameter profile are obtained.

[0071] The preset time period in step S5 is more than 10 years.

[0072] Wherein, in step S2, ground stress analysis is performed based on GMI software.

[0073] Among them, in step S2, the Model Builder module in the drilling optimization design software is used to calculate the dynamic rock mechanics parameter profile and the ground stress parameter profile.

[0074] Among them, in step S4, based on the SFIB module in the GMI software, the effective rock mechanics parameters obtained in step S3 and the drilling parameters of the target well are inverted to obtain the maximum horizontal principal stress parameters. The maximum horizontal principal stress is obtained by inversion with the help of the geostress software. Inversion represents a process of using the software. The effective rock mechanics parameters, including cohesion, compressive strength, minimum horizontal principal stress and other parameters, are input in the software window, and then run. The maximum horizontal principal stress parameters are obtained by limiting the accurate uniaxial compressive strength and minimum horizontal principal stress.

[0075] Among them, establishing the target gas well perforation completion model specifically includes the following steps:

[0076] Based on finite element software, the perforation completion model of the target gas well is constructed, which mainly includes three parts: perforation casing, cement ring, and formation model; each part defines different properties according to reservoir and component parameters. The input of the model is mainly reflected in the setting of boundary and load conditions, and the output is mainly based on the stress size of the simulation results.

[0077] The specific input includes the setting of the original ground stress field, the assignment of formation pressure, the setting of casing perforation parameters, etc., which are implemented in different windows of the software. Under different input conditions, the stress cloud map is finally obtained and compared with the original rock compressive strength for case analysis.

[0078] Example 2

[0079] According to a specific embodiment of the present invention, the reservoir stability evaluation method during the production process of an ultra-high pressure gas well of the present invention is described in detail below.

[0080] The establishment process of a reservoir stability evaluation method in the production process of an ultra-high pressure gas well provided by the present invention is shown in Figure 1 , which is carried out from three aspects, mainly including indoor rock mechanics parameter experiments, GMI numerical simulation and the establishment of a finite element perforation completion wellbore instability evaluation model. The specific implementation of this embodiment is as follows:

[0081] Several groups of rock mechanics parameter experiments were carried out, and different groups of experimental plans were formulated according to actual needs, mainly including 3 groups (core samples were taken from 3 different reservoir sections to ensure more accurate tensile strength of the entire reservoir section) Brazilian splitting tensile test; 6 groups of P- and S-wave scanning experiments (2 groups in each of the 3 reservoir sections to maximize the accuracy of the fitting data) to obtain P- and S-wave velocities; 6 groups of triaxial + 3 groups of uniaxial compression experiments. Taking into account the actual formation conditions, abnormally high temperature and high pressure, temperature of 150℃, pressure of 149MPa, 6 groups of triaxial experiments were carried out at 150℃. Considering the influence of confining pressure on rock strength, the compressive strength under 6 different ground pressure gradient conditions was tested respectively. 3 groups of uniaxial experiments were carried out at room temperature to finally obtain the uniaxial compressive strength of rock.

[0082] For abnormally high temperature and high pressure formations, the stress field changes are very complex. Therefore, the acoustic emission Kessel effect experiment is carried out to determine the strength of the formation stress field. According to the needs, the cores are sampled at 0°, 45°, and 90°. Considering the influence of pressure depletion on ground stress, the ground stress sizes under three groups of confining pressures are tested respectively. It is assumed that the maximum formation pressure limits depletion until normal production is impossible, and finally the reservoir stress field profile is obtained.

[0083] Based on GMI-MoudelBuilder software, the actual situation of the formation is deeply analyzed. The logging data can truly reflect the characteristics of the formation rock. According to the simulation requirements, 5 logging curves are selected, mainly including acoustic wave curve, resistivity curve, gamma curve, caliper curve, and density curve. They are loaded into the software for curve splicing and synthesis to obtain the complete logging curve of the reservoir section. The resistivity curve is used to divide the reservoir lithology, and the pseudo-density curve is extracted from the acoustic wave curve to integrate and calculate the vertical stress. Finally, a series of rock mechanical parameter profiles, overlying rock stress profiles, and minimum horizontal principal stress profiles are obtained. Figure 3 .

[0084] Based on steps 0001 and 0002, the single-point static parameters of the reservoir section are obtained through indoor experiments, and the continuous dynamic parameter profile obtained based on the logging data in step 0003 is corrected. First, the rock mechanical parameter profile and stress parameter profile (both dynamic parameters) of the entire reservoir section can be obtained based on the logging data, but since the logging data can only obtain the longitudinal wave data and the transverse wave data is missing, the subsequent parameters are calculated based on the empirical formula, and the parameter calculation results have large errors, so parameter correction is required; secondly, through the indoor acoustic wave time difference experiment, the longitudinal and transverse wave conversion relationship can be accurately obtained, and then the single-point static mechanical parameters of the reservoir section can be calculated, and then the dynamic and static rock mechanical parameter conversion relationship can be obtained by calculating the size of the mechanical parameters of the same layer; finally, the continuous static mechanical parameter profile of the reservoir section is obtained through the dynamic and static relationship, and the stress parameter value obtained by the experiment is imported into the model through the software stress size loading window to correct the stress parameter profile obtained based on the logging data, and the continuous rock mechanical parameter profile and the overlying rock stress and minimum horizontal principal stress profile after correction are obtained.

[0085] Combined with the target reservoir drilling and completion parameters and accurate rock mechanics parameters, they are imported into the GMI-BSFI model for inversion calculation of the maximum horizontal principal stress. The inversion calculation results are shown in Figure 4 (The strata are always in a state of equilibrium, therefore, they must be Figure 4In the stress polygon, NF is the normal fault stress field, ss is the strike-slip stress field, and RF is the reverse fault stress field, corresponding to the vertical principal stress as the maximum principal stress, the vertical principal stress as the intermediate principal stress, and the vertical principal stress as the minimum principal stress. After clarifying the rock mechanical parameters, pore pressure value, minimum horizontal principal stress direction, minimum horizontal principal stress, and vertical principal stress at a certain depth, the maximum horizontal principal stress at that location can be inverted. In the stress polygon, the blue line represents the rock tensile strength, the red line represents the rock single extraction compressive strength, the horizontal axis represents the minimum horizontal principal stress, and the vertical axis represents the maximum horizontal principal stress. Any position in the polygon contains a stress field), and the final complete rock mechanical parameters are shown in Table 1.

[0086] Based on ABAQUS software, a perforation and completion finite element model of the target gas well was established, and the corrected rock mechanics parameters and geostress parameters (see Table 1) were imported. The rock mechanics parameters in Table 1, target reservoir parameters, and drilling and completion parameters were loaded into the perforation and completion finite element evaluation model to simulate the geostress variation law in different perforation schemes under 10-year variable formation pressure, analyze the influence of formation pressure, production pressure difference, and perforation parameters on the wellbore stability of high-pressure gas wells, determine the critical sanding pressure difference of high-pressure gas wells in the entire life cycle, and determine the reasonable production system of service gas wells. Among them, the formation pressure can be changed as a variable parameter in the software boundary condition setting, and the perforation and completion parameters can be changed in the model establishment.

[0087] Table 1 Rock mechanical parameter values ​​obtained based on experimental and simulation corrections

[0088]

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for evaluating reservoir stability during the production process of an ultra-high pressure gas well, characterized in that: The steps include: Step S1: Obtain rock samples of the target reservoir section, conduct rock mechanics parameter experiments and geostress experiments, and obtain static rock mechanics parameters and reservoir geostress magnitude; Step S2: preprocessing the target reservoir section logging data, and obtaining a dynamic rock mechanics parameter profile and a geostress parameter profile based on the preprocessed target reservoir section logging data; Step S3: Correct the static rock mechanical parameters and geostress values ​​obtained from the rock mechanical parameter experiment and geostress experiment in step S1, and combine the dynamic rock mechanical parameter profile and geostress parameter profile obtained in step S2 to obtain effective rock mechanical parameters, and then obtain a dynamic and static rock mechanical parameter fitting relationship map; Step S4: combining the dynamic and static rock mechanics parameter fitting relationship map obtained in step S3 and the target well drilling parameter inversion to obtain the maximum horizontal principal stress parameter; Step S5: Establish a perforation and completion finite element model of the target gas well, determine the critical sand production pressure difference of the high-pressure gas well in the whole life cycle of the rock according to the effective rock mechanics parameters and ground stress parameters, and determine the stability of the reservoir during the production of the ultra-high-pressure gas well according to the critical sand production pressure difference of the high-pressure gas well.

2. The reservoir stability evaluation method during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: In step S5, effective rock mechanics parameters and geostress parameters are imported into the established finite element model of the target gas well perforation completion, and the geostress variation law in different perforation schemes under different formation pressures within a preset time period is simulated. The influence of formation pressure, production pressure difference and perforation parameters on the wellbore stability of the high-pressure gas well is analyzed, and the critical sand production pressure difference of the high-pressure gas well in the whole life cycle is determined. The stability of the reservoir during the production of the ultra-high-pressure gas well is determined according to the critical sand production pressure difference of the high-pressure gas well.

3. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: Rock mechanics parameter experiments include Brazilian splitting, longitudinal and shear wave continuous scanning experiments and triaxial compression tests.

4. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 3, characterized in that: The tensile strength is obtained through the Paris splitting test; the longitudinal wave data, shear wave data and dynamic Poisson's ratio are obtained through the longitudinal and shear wave continuous scanning experiment; the static Poisson's ratio, static elastic modulus, compressive strength and cohesion are obtained through the triaxial compression test.

5. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: The ground stress experiment is an acoustic emission Kessel effect experiment, which is used to predict the magnitude of ground stress.

6. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: In step S2, the logging data of the target reservoir section are fitted and the lithology is divided to obtain the acoustic cancellation, wellbore cancellation, resistivity cancellation, gamma curve and density curve, and then the dynamic rock mechanics parameter profile and the ground stress parameter profile are obtained.

7. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: The preset time period in step S5 is more than 10 years.

8. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: In step S2, ground stress analysis is performed based on GMI software.

9. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: In step S2, the Model Builder module in the drilling optimization design software is used to calculate the dynamic rock mechanics parameter profile and the ground stress parameter profile.

10. The method for evaluating reservoir stability during the production process of an ultra-high pressure gas well according to claim 1, characterized in that: In step S4, based on the SFIB module in the GMI software, the maximum horizontal principal stress parameters are inverted in combination with the effective rock mechanics parameters obtained in step S3 and the drilling parameters of the target well.

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