Geomechanical constrained fault conductivity analysis method

Abstract

The invention discloses a geomechanical constrained fault conductivity analysis method, and belongs to the technical field of geological exploration. The method specifically comprises the following steps: S1, acquiring basic data and preprocessing data: acquiring various basic data required for conductivity analysis, and preprocessing the acquired basic data; s2, fault activity evaluation: analyzing the activity of the fault according to the preprocessed corresponding data; s3, fault permeability evaluation: quantitatively evaluating the permeability of the fault and surrounding rocks. The method comprises the following steps: acquiring analysis times of the analysis method, verification of analysis accuracy times, analysis results of each time and field data acquisition analysis results after each time of analysis, and comprehensively analyzing the data to obtain an accurate index of the analysis method, so that the analysis method is evaluated according to the accuracy index of the analysis method. The larger the accuracy index of the analysis method is, the higher the accuracy of the analysis method is.

Description

Technical Field

[0001] The present invention relates to the technical field of geological exploration, and particularly to a method for analyzing the conductivity of faults constrained by geomechanics. Background Art

[0002] The migration of oil and gas plays an important controlling role in the hydrocarbon accumulation in basins. Whether oil and gas can migrate depends, in addition to the presence of oil and gas sources, on the migration channels and driving forces. Faults are important factors in forming oil and gas channels, and pressure is an important condition for the migration of oil and gas.

[0003] Regarding the study of the oil and gas conductivity of faults, many scholars at home and abroad have proposed various methods and theories starting from the fault sealing mechanism. Looking at the technologies and methods proposed by predecessors, they mainly focus on the current state of faults and qualitatively and semi-quantitatively analyze the conductivity of faults to oil and gas from the perspectives of fault geometry and kinematics. For the study of pressure, it mainly analyzes the current characteristics of formation pressure and its influence on the migration of oil and gas based on geophysical means and borehole measurement data, without considering the influence of paleo-pressure changes on migration. At the same time, when studying the migration of oil and gas in the industry at present, the influence of each factor on the migration of oil and gas is often considered in isolation, without considering the coupling effect between factors. However, the hydrocarbon accumulation process experiences a long geological history and is a dynamic evolution process affected by many factors. The existing evaluation of the fault conductivity mainly focuses on the study of faults during the active period, and the description of the conductivity of faults that are static during the key hydrocarbon accumulation period is significantly insufficient, reducing the accurate evaluation of the migration amount of oil and gas along faults and affecting the drilling success rate. At the same time, the existing analysis methods do not verify the analysis results through on-site data and do not evaluate the analysis methods in real time according to the analysis results to determine whether the analysis methods need to be optimized and adjusted. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a method for analyzing the conductivity of faults constrained by geomechanics, which can solve the problem that the existing analysis methods do not verify the analysis results through on-site data and do not evaluate the analysis methods in real time according to the analysis results to determine whether the analysis methods need to be optimized and adjusted.

[0005] Technical Solution: To solve the above technical problems, according to one aspect of the present invention, more specifically, a method for analyzing the conductivity of faults constrained by geomechanics specifically includes the following steps:

[0006] S1. Collect basic data and data preprocessing: Collect various basic data required for conductivity analysis, and preprocess the collected basic data;

[0007] S2. Fault activity evaluation: Analyze the activity of faults through the corresponding preprocessed data.

[0008] S3. Fault permeability assessment: Quantitatively evaluate the permeability of the fault and surrounding rocks;

[0009] S4. Data simulation and analysis: Simulate the data by constructing a three-dimensional geomechanical model and conduct multi-field simulation coupling;

[0010] S5. Geological evidence verification and verification result recording: Verify the analysis results by collecting on-site data and record the verification results;

[0011] S6. Analysis and feedback of verification results: Analyze the verification results to obtain the evaluation index of the current analysis method, and determine whether to optimize and adjust the current analysis method based on the current verification results.

[0012] Furthermore, in the step S1, the basic data collected includes: geological data, stress data, rock mechanics data, and fluid and pressure data.

[0013] Furthermore, in the step S2, during the activity evaluation process, the actual shear stress can be obtained by acquiring the shear stress, normal stress, and pore pressure on the fault plane:

[0014] τ = μ(σ n - p p )

[0015] Meanwhile:

[0016] σ ′ n = σ n - u

[0017] If the calculated value of τ is equal to σ ′ n at this time, it means that the fault is in a critical state, and a slight pressure fluctuation can trigger sliding to form a conduction channel; where τ is the actual shear stress on the fault plane, μ is the friction coefficient, and its value ranges from 0.6 to 0.85 and is determined by the fault material, σ n is the normal stress on the fault plane, p p is the pore pressure, σ′ n is the effective stress, and u is the pore water pressure.

[0018] Furthermore, in the step S2, when evaluating the fault activity, the fault slip tendency can be obtained through the analysis of the actual shear stress and the effective stress:

[0019] T s = τ / σ′ n

[0020] Thus, the sliding risk of the fault can be determined according to the fault slip tendency. When T sWhen it is > 0.6, it indicates that the fault is at high sliding risk and there is a risk of periodic increase in permeability; when T s < 0.4, it indicates that the fault is stable and the permeability is controlled by mineral filling.

[0021] Furthermore, in the step S3, the method for evaluating the fault permeability includes, but is not limited to, evaluating the fault permeability by one of laboratory testing of core permeability, well logging data analysis to calculate the Caine model.

[0022] Furthermore, the process of data simulation and analysis is to integrate geological, mechanical, and fluid data to construct a three-dimensional model; define the stress-seepage-temperature interaction mechanism; embed the evolution laws of permeability and friction coefficient; run the model and compare with the actual observed data.

[0023] Furthermore, in the step S5, when verifying the analysis result through field data, analyze the relevant data of the analysis accuracy of the verification analysis result through field data, and record the relevant data of the analysis accuracy of the analysis result at the verification site.

[0024] Furthermore, in the step S6, when analyzing the verification result, obtain the number of analysis times of this analysis method, the number of times of accurate verification analysis, each analysis result, and the analysis result of on-site data collection after each analysis, and comprehensively analyze the above data to obtain the accuracy index of this analysis method, so as to determine the evaluation of this analysis method through the accuracy index of this analysis method. The larger the accuracy index of this analysis method, the higher the accuracy of this analysis method; otherwise, it indicates that the accuracy of this analysis method is lower.

[0025] Furthermore, in the step S6, after obtaining the accuracy index of this analysis method, compare it with the threshold of the accuracy index set in advance. When the accuracy index is greater than the threshold of the accuracy index set in advance, no optimization adjustment of the analysis method is performed; when the accuracy index is not greater than the threshold of the accuracy index set in advance, it indicates that optimization adjustment of the analysis method is required.

[0026] Beneficial effects: Through the evaluation of fault activity, the evaluation of fault permeability, and the data simulation and analysis at multiple levels, and the conductivity analysis of multiple data items, the analysis results are more accurate, and it can effectively avoid the situation where the analysis results are not objective enough caused by the isolated analysis of a single factor. And after the analysis is completed, the analysis results are verified through on-site geological data, so as to effectively master the analysis accuracy of the analysis method. At the same time, by obtaining the number of analysis times of this analysis method, the number of times of verifying the analysis accuracy, each analysis result, the on-site data collection and analysis results after each analysis, and comprehensively analyzing the above data, the accuracy index of this analysis method is obtained. Thus, the evaluation of this analysis method is determined through the accuracy index of this analysis method. The larger the accuracy index of this analysis method, the higher the accuracy of this analysis method; on the contrary, it indicates that the accuracy of this analysis method is lower. And after obtaining the accuracy index of this analysis method, it will be compared with the preset threshold of the accuracy index. When the accuracy index is greater than the preset threshold of the accuracy index, no optimization and adjustment of the analysis method will be carried out. When the accuracy index is not greater than the preset threshold of the accuracy index, it means that the optimization and adjustment of the analysis method are required, and it can be timely fed back to the corresponding personnel to optimize and adjust the analysis method, thereby improving the adaptability during the use of the analysis method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the method flow. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the technical solutions of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

[0029] Embodiment 1

[0030] First step, collecting basic data and data preprocessing: Collect various basic data required for conductivity analysis, including geological data, stress data, rock mechanics data, and fluid and pressure data, and preprocess the collected basic data so that the units of each item are unified to meet the requirements for subsequent conductivity analysis.

[0031] Fault permeability evaluation: Quantitatively evaluate the permeability of the fault and surrounding rocks. During the activity evaluation process, the actual shear stress can be obtained by obtaining the shear stress, normal stress, and pore pressure on the fault plane:

[0032] τ = μ(σ n -p p )

[0033] At the same time, there is:

[0034] σ ′ n = σn -u

[0035] In the second step, if the calculated value of τ is equal to σ ′ n , it indicates that the fault is in a critical state, and a slight pressure fluctuation can trigger sliding to form a conduction channel; where τ is the actual shear stress on the fault plane, μ is the friction coefficient, and its value ranges from 0.6 to 0.85, which is determined by the fault material, and σ n is the normal stress on the fault plane, p p is the pore pressure, and σ ′ n is the effective stress, and u is the pore water pressure.

[0036] In the third step, fault permeability assessment: Quantitatively evaluate the permeability of the fault and surrounding rocks by one method including but not limited to laboratory testing of core permeability, well logging data analysis, and the Caine model.

[0037] In the fourth step, data simulation and analysis: Simulate the data by constructing a three-dimensional geomechanical model and perform multi-field simulation coupling. The specific process is as follows: Integrate geological, mechanical, and fluid data to construct a three-dimensional model; Define the stress-seepage-temperature interaction mechanism; Embed the evolution laws of permeability and friction coefficient; Run the model and compare with actual observed data.

[0038] In the fifth step, geological evidence verification and verification result recording: Verify the analysis results by collecting on-site data to verify the relevant data of the analysis accuracy of the analysis results, and record the relevant data of the analysis accuracy of the analysis results at the verification site.

[0039] In the sixth step, analysis and feedback of verification results: Analyze the verification results to obtain the evaluation index of the current analysis method. When analyzing the verification results, obtain the number of analyses of this analysis method, the number of times of accurate verification analysis, each analysis result, the analysis result of on-site data collection after each analysis, and comprehensively analyze the above data to obtain the accuracy index of this analysis method. Then, evaluate this analysis method based on the accuracy index of this analysis method. The larger the accuracy index of this analysis method, the higher the accuracy of this analysis method; otherwise, it indicates that the accuracy of this analysis method is lower.

[0040] Determine whether to optimize and adjust the current analysis method according to the feedback of the current verification results. After obtaining the accuracy index of this analysis method, compare it with the preset threshold of the accuracy index. When the accuracy index is greater than the preset threshold of the accuracy index, no optimization and adjustment of the analysis method will be performed. When the accuracy index is not greater than the preset threshold of the accuracy index, it indicates that optimization and adjustment of the analysis method are required.

[0041] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A geomechanically constrained fault conductivity analysis method, characterized in that: The specific steps include: S1. Collecting basic data and preprocessing data: Collecting various basic data required for conductivity analysis and preprocessing the collected basic data; S2. Fault activity evaluation: Analyze the activity of the fault by preprocessing the corresponding data; S3. Fault permeability assessment: quantitative assessment of the permeability of the fault and surrounding rocks; S4. Data simulation and analysis: Simulate the data by constructing a three-dimensional geomechanical model and perform multi-field simulation coupling; S5. Verification of geological evidence and recording of verification results: Verify the analysis results by collecting field data and record the verification results; S6. Verification result analysis and feedback: Analyze the verification results to obtain the evaluation index of the current analysis method, and determine whether to optimize and adjust the current analysis method based on the current verification result feedback.

2. The geomechanically constrained fault conductivity analysis method according to claim 1, characterized in that: In step S1, the basic data collected include geological data, stress data, rock mechanics data, and fluid and pressure data.

3. The geomechanically constrained fault conductivity analysis method according to claim 1, characterized in that: In step S2, during the activity evaluation process, the actual shear stress can be obtained by obtaining the shear stress, normal stress and pore pressure on the fault plane: τ=μ(σ n -p p ) Also available: in n =s n -u If the calculated value of τ is equal to σ′ n When , it means that the fault is in a critical state, and a slight pressure fluctuation can trigger sliding and form a transmission channel; where τ is the actual shear stress on the fault surface, μ is the friction coefficient, which is 0.6-0.85 and is determined by the fault material, and σ n is the normal stress on the fault plane, p p is the void pressure, σ′ n is the effective stress and u is the pore water pressure.

4. The geomechanically constrained fault conductivity analysis method according to claim 3, characterized in that: In step S2, when evaluating the fault activity, the fault slip tendency can be obtained by analyzing the actual shear stress and the effective stress: T s =t / s′ n The slip risk of the fault is determined according to the slip tendency of the fault. s When T >0.6, it means that the fault is at high risk of slip and the permeability has a risk of periodic enhancement. s <0.4, indicating that the fault is stable and the permeability is controlled by mineral filling.

5. The geomechanically constrained fault conductivity analysis method according to claim 1, characterized in that: In step S3, the method for evaluating the fault permeability includes but is not limited to laboratory testing of core permeability, and analysis of well logging data to evaluate the fault permeability using one of the Caine models.

6. The geomechanically constrained fault conductivity analysis method according to claim 1, characterized in that: In step S4, the process of data simulation and analysis is to integrate geological, mechanical, and fluid data to build a three-dimensional model; define the stress-seepage-temperature interaction mechanism; embed the evolution law of permeability and friction coefficient; run the model and compare it with actual observation data.

7. The geomechanically constrained fault conductivity analysis method according to claim 1, characterized in that: In the step S5, when the analysis result is verified by the field data, the relevant data of the analysis accuracy of the analysis result is verified by the field data, and the relevant data of the analysis accuracy of the analysis result at the verification is recorded.

8. The geomechanically constrained fault conductivity analysis method according to claim 7, characterized in that: In step S6, when performing verification result analysis, the accuracy index of the analysis method is obtained by obtaining the number of analyses of the analysis method, the number of times the analysis is accurate, the result of each analysis, and the analysis result of field data collection after each analysis, and a comprehensive analysis is performed on the above data, so as to obtain the accuracy index of the analysis method, and then the analysis method is evaluated by determining the accuracy index of the analysis method. The larger the accuracy index of the analysis method, the higher the accuracy of the analysis method, and vice versa.

9. The method for analyzing fault conductivity constrained by geomechanics according to claim 8, characterized in that: In step S6, after the accuracy index of the analysis method is obtained, it will be compared with the preset threshold of the accuracy index. When the accuracy index is greater than the preset threshold of the accuracy index, the analysis method will not be optimized. When the accuracy index is not greater than the preset threshold of the accuracy index, it indicates that the analysis method needs to be optimized.

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