Quantitative relation chart construction method based on fault characteristics and stress disturbance

Abstract

The invention discloses a quantitative relation chart construction method based on fault characteristics and stress disturbance in the technical field of oil-gas exploration and development. The method comprises the following steps: constructing a geological structure model; the geologic structure model is converted into a mechanical model, and stratum three-dimensional heterogeneous geomechanical attribute modeling is completed through single-point test analysis, single-well logging interpretation and plane distribution simulation; importing the established three-dimensional heterogeneous rock mechanical parameter model by using modeling software, endowing rock mechanical parameters, and performing grid division on the imported model to generate a grid mathematical model; taking a three-dimensional heterogeneous rock mechanical parameter model as a parameter model for crustal stress prediction, and setting a boundary load loading mode; through finite element calculation, the current crustal stress distribution characteristics of the research area are obtained. According to the scheme, through the technical means of single-point test analysis, single-well logging interpretation, plane distribution simulation and the like, the mechanical properties of the rock under different conditions can be described more accurately.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration and development, and specifically is a method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance. Background Art

[0002] In geological exploration and oil and gas field development, the impact of fault activity on formation stress is an important and complex issue. Fault activity is often accompanied by stress redistribution and local stress concentration, that is, stress disturbance. Stress disturbance is the mechanical response of fault activity to the surrounding rocks. Its size and range have an important impact on oil and gas exploration and development. However, due to the complexity of rock mechanical properties and the diversity of formation structure, traditional stress assessment methods often find it difficult to accurately reflect the actual situation of stress disturbance. For example, when rocks are subjected to stress, their stress-strain relationship may show nonlinear characteristics. Traditional assessment methods are usually based on linear elastic theory, which makes it difficult to fully consider these complex properties of rocks. In particular, when there is fault activity, the formation structure becomes more complex, and traditional assessment methods find it even more difficult to accurately reflect the impact of faults on formation stress.

[0003] Therefore, there is an urgent need for a quantitative assessment method that reflects the ground stress disturbance caused by different types of faults, which can improve the quantification accuracy of the stress disturbance range. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a method for constructing a quantitative relationship chart based on fault characteristics and stress disturbances, which can improve the quantification accuracy of the stress disturbance range.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for constructing a quantitative relationship chart based on fault characteristics and stress disturbances includes the following steps:

[0007] Construct geological structure model based on stratigraphic division and attribute assignment;

[0008] The geological structure model is converted into a mechanical model based on material properties and structural properties. The three-dimensional heterogeneous geomechanical property modeling of the formation is completed through single-point test analysis, single well logging interpretation, and plane distribution simulation, and a three-dimensional heterogeneous rock mechanical parameter model is generated;

[0009] Use modeling software to import the established three-dimensional heterogeneous rock mechanics parameter model, assign corresponding rock mechanics parameters to geological units, mesh the imported model according to the finite element division principle, and generate a mesh mathematical model;

[0010] The three-dimensional heterogeneous rock mechanics parameter model is used as the parameter model for ground stress prediction, and the initial value of the boundary condition is determined according to the regional structural analysis. The ground stress data of a single well test is used as the constraint condition to set the boundary load loading method.

[0011] Through finite element calculation, the current distribution characteristics of ground stress in the study area are obtained.

[0012] Further, the single point test analysis includes the following steps:

[0013] Geological data collection: Collect geological data of the study area, including core description, well logging data, seismic data, and geochemical data;

[0014] Rock mechanical properties analysis: laboratory testing based on core samples to obtain the mechanical parameters of the rock;

[0015] Data recording and analysis: The data obtained from the test are recorded and statistically analyzed to evaluate the approximate range of rock mechanical parameters at that point.

[0016] Further, the single well logging interpretation includes the following steps:

[0017] Using the P-wave time difference, S-wave time difference and density data in the well logging data of the study area, Young's modulus and Poisson's ratio are calculated by the following formula;

[0018]

[0019] Among them, E d is Young's modulus; μ d is Poisson's ratio; ρ is rock density; Δt p is the longitudinal wave time difference; Δt s is the shear wave time difference;

[0020] Combined with the core triaxial stress test data of the study area, the Young's modulus and Poisson's ratio after well logging correction in the study area were calculated.

[0021] Based on the corrected Young's modulus and Poisson's ratio, the formation characteristics, rock properties and fluid content in the well are interpreted.

[0022] Further, the plane distribution simulation includes the following steps:

[0023] Collect well logs and seismic data in the study area;

[0024] Use logging data and seismic data to make cross-well predictions and construct three-dimensional lithofacies models;

[0025] Combining the elastic parameter constraints of 3D seismic attribute inversion and the rock mechanics parameter test values ​​of well points in different tectonic zones, anisotropic sequential Gaussian random simulation is performed to obtain the 3D inhomogeneous rock mechanics parameter field distribution map of the study area.

[0026] The rock mechanical zoning of the study area is carried out according to the simulated rock mechanical parameter distribution map.

[0027] Furthermore, when setting the boundary load loading mode, the well point measured value S and the predicted value x have the following relationship:

[0028] S i =A i x i +e i

[0029] Where [A] is the coefficient matrix, [S] is the measured stress matrix of the well point, [x] is the predicted value matrix, and e is the error between the measured value and the predicted value.

[0030] Furthermore, when setting the boundary load loading method, the difference function between the well point predicted value and the measured value is used as the objective function. When the accuracy of the objective function reaches the preset requirement, the reasonable boundary conditions are determined.

[0031] Furthermore, the objective function is formulated as follows:

[0032] Furthermore, the current geostress distribution characteristics include the direction and value of the maximum horizontal principal stress, the minimum horizontal principal stress, the vertical principal stress, and the horizontal stress difference.

[0033] Furthermore, stratigraphic division includes division based on geological age, lithology, and sedimentary environment.

[0034] Furthermore, when meshing the model, three-node triangular elements are used to divide the mesh units of the fault and its surrounding area into smaller than the preset area.

[0035] The above scheme has the following beneficial effects:

[0036] 1. This scheme, through technical means such as single-point test analysis, single-well logging interpretation, and plane distribution simulation, can accurately describe the mechanical properties of rocks under different conditions, including their nonlinear behavior, so as to better quantitatively analyze the stress disturbance caused by fault activity.

[0037] 2. This scheme can accurately depict the morphology and distribution of faults of different levels in three-dimensional space by using the fracture surface morphology and fracture zone width value plates interpreted by three-dimensional seismic. This high-precision modeling is essential for understanding the geometric characteristics, movement history and evolution of the fault system. In the fields of geological engineering, oil and gas exploration and earthquake disaster prediction, accurate three-dimensional geological structure models of faults are the basis for analyzing and predicting underground fluid flow, stress distribution and seismic activity.

[0038] 3. Since there are often complex crack networks inside the fracture, these cracks have a significant impact on the mechanical properties of the rock. This scheme can accurately describe the mechanical properties of the rock inside the fracture of different stages, including Young's modulus, Poisson's ratio, shear modulus, etc., by using the elastic parameter assignment chart of the fractured rock. The three-dimensional heterogeneous rock mechanical property modeling can more realistically reflect the mechanical response and deformation behavior of the underground rock, and provide more accurate parameter support for geological engineering design and earthquake risk assessment.

[0039] 4. This solution, combined with the three-dimensional geological structure modeling of fractures and the three-dimensional mechanical property modeling of heterogeneous rocks, can form a complete underground model that integrates geometric characteristics and mechanical properties. Such a model has higher accuracy and reliability in predicting underground stress distribution and seismic activity. In oil and gas exploration, it can help engineers more accurately assess the development potential and risks of oil and gas reservoirs; in geological disaster prediction, it can provide a more scientific basis for earthquake risk assessment and disaster warning. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of a flow chart of an embodiment of the present invention.

[0041] Figure 2 This is an interpretation diagram of the in-situ stress profile of a single well in the organic-rich shale of the Longmaxi Formation according to an embodiment of the present invention.

[0042] Figure 3 This is a plane distribution diagram of the Young's modulus of the bottom boundary of the Wufeng Formation in an embodiment of the present invention.

[0043] Figure 4 This is a rock mechanical property zoning and heterogeneity modeling for an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the regional geological structure model studied in an embodiment of the present invention.

[0045] Figure 6 This is a three-dimensional geological structure modeling diagram of different levels of faults in the study area of ​​the embodiment of the present invention.

[0046] Figure 7 This is a schematic diagram of the grid division of the research area according to an embodiment of the present invention.

[0047] Figure 8 This is a diagram of the Young's modulus correction model for the study area of ​​the embodiment of the present invention.

[0048] Fig. 9 This is a diagram of the Poisson's ratio correction model for the study area of ​​the embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following is further described in detail through specific implementation methods:

[0050] The embodiment is basically as shown in the attached Figure 1-Figure 9 As shown:

[0051] A method for constructing a quantitative relationship chart based on fault characteristics and stress disturbances includes the following steps:

[0052] Construct geological structure model based on stratigraphic division and attribute assignment;

[0053] Specifically, by collecting geological data, including borehole data, geological profiles, seismic profiles, etc., these data will provide a basis for stratigraphic division and attribute assignment. Then establish a database to organize and classify all collected data to ensure data consistency and accuracy. On the basis of a comprehensive investigation and understanding of the study area, use surveying and mapping data (such as topographic maps, aerial photographs, satellite images, etc.) to divide the stratigraphy based on geological age, lithology, and sedimentary environment. Through field observation and exploration, further geological data, such as geological drilling data, are obtained to verify and correct the results of stratigraphic division. In the process of stratigraphic division, it is necessary to pay attention to the depositional sequence of each stratum and the contact relationship between each stratum to ensure the accuracy and rationality of the stratigraphic division.

[0054] Select appropriate modeling software, such as Flack3D, and set the coordinate system.

[0055] Import the collected geological data into the modeling software and perform data entry, stratigraphic arrangement, etc. This includes defining model boundaries, defining fault properties, etc., and defining the geological significance of all imported data.

[0056] In the stratum arrangement stage, control points can be added or reduced in each stratum data as needed, and the color and other attributes of each stratum can be adjusted. The appropriate interpolation method and the completed variogram can be selected to gradually complete the attribute assignment.

[0057] After completing data entry, stratum organization and attribute assignment, use modeling software to generate a geological structure model, as shown in the attached Figure 5 shown.

[0058] The geological structure model is converted into a mechanical model based on material properties and structural properties, and the three-dimensional heterogeneous geomechanical property modeling of the formation is completed through single-point test analysis, single well logging interpretation, and plane distribution simulation, and a three-dimensional heterogeneous rock mechanical parameter model is generated;

[0059] Specifically, after establishing the geological structure model of the target layer in the study area, in order to conduct mechanical analysis, it is necessary to convert the geological model into a mechanical model. This conversion process involves determining the properties of different materials and structural attributes, meshing the model, and assigning rock mechanical properties, which specifically includes the following steps:

[0060] Analyze the geological structure model of the target layer in the study area and identify different strata and structural units.

[0061] Determine the material properties of different strata and tectonic units, such as rock type, density, strength, etc., based on geological information, core analysis, laboratory testing and other data.

[0062] Further research is needed to understand the structural properties of these materials, such as anisotropy, bedding, and joints, which will affect the mechanical behavior of rocks.

[0063] After determining the material properties and structural attributes through the above steps, the geological model is converted into a mechanical model.

[0064] The three-dimensional heterogeneous geomechanical attribute modeling of the strata in the study area was completed through three steps: single-point test analysis, single-well logging interpretation, and plane distribution simulation;

[0065] Specifically, the single-point test analysis includes the following steps:

[0066] Geological data collection: Collect geological data of the study area, including core description, well logging data, seismic data, and geochemical data;

[0067] Rock mechanical properties analysis: laboratory testing based on core samples to obtain the mechanical parameters of the rock;

[0068] Data recording and analysis: The data obtained from the test are recorded and statistically analyzed to evaluate the approximate range of rock mechanical parameters at that point.

[0069] Single well logging interpretation includes the following steps:

[0070] Using the P-wave time difference, S-wave time difference and density data in the well logging data of the study area, Young's modulus and Poisson's ratio are calculated by the following formula;

[0071]

[0072]

[0073] Among them, E d is Young's modulus; μ d is Poisson's ratio; ρ is rock density; Δt p is the longitudinal wave time difference; Δt s is the shear wave time difference;

[0074] Combined with the core triaxial stress test data in the study area, the Young's modulus and Poisson's ratio after well logging correction in the study area were calculated, as shown in the attached figure. Figure 8 and attached Fig. 9 As shown;

[0075] Based on the corrected Young's modulus and Poisson's ratio, the formation characteristics, rock properties and fluid content in the well are interpreted.

[0076] Plane distribution simulation includes the following steps:

[0077] Collect well logs and seismic data in the study area;

[0078] Use logging data and seismic data to make cross-well predictions and construct three-dimensional lithofacies models;

[0079] Combining the elastic parameter constraints of 3D seismic attribute inversion and the rock mechanics parameter test values ​​of well points in different tectonic zones, anisotropic sequential Gaussian random simulation is performed to obtain the 3D inhomogeneous rock mechanics parameter field distribution map of the study area.

[0080] The rock mechanical zoning of the study area is carried out according to the simulated rock mechanical parameter distribution map.

[0081] The single-point test analysis results are shown in Table 1, and the single-well logging interpretation results are shown in Appendix. Figure 2 The plane distribution simulation results are shown in the attached Figure 3-Figure 4 As shown in the figure, the rock mechanics zoning of the study area is carried out according to the simulated rock mechanics parameter distribution map, which is divided into five types: A, B, C, D, and E. The rock mechanics parameter values ​​of each sublayer in each zone are shown in Table 2.

[0082] Table 1 Data of triaxial high temperature and high pressure rock mechanics experiment on Longmaxi shale

[0083]

[0084]

[0085] Table 2 Table of heterogeneous rock mechanics assignments for each layer in each rock mechanics zone in the study area

[0086]

[0087]

[0088] The established three-dimensional heterogeneous rock mechanics parameter model is imported using modeling software, and the corresponding rock mechanics parameters are assigned to the geological body units. The imported model is meshed according to the finite element division principle to generate a mesh mathematical model. When meshing the model, three-node triangular elements are used to divide the mesh units of the fault and its surrounding areas into smaller areas than the preset area, that is, the mesh units of the fault and its surrounding areas are smaller and the mesh density is larger, while the mesh scale of other areas is larger and the density is smaller.

[0089] Specifically, as attached Figure 7 As shown, the meshing of the model has a total of 2226107 nodes and 830038 units, of which the Wufeng Group has 791760 nodes and 295220 units; the Long 11 segment has 172121 nodes and 64178 units; the Long 12 segment has 585214 nodes and 218206 units; and the Long 13 has 677012 nodes and 252434 units.

[0090] The three-dimensional heterogeneous rock mechanics parameter model is used as the parameter model for ground stress prediction, and the initial value of the boundary condition is determined according to the regional structural analysis. The ground stress data of a single well test is used as the constraint condition to set the boundary load loading method.

[0091] Specifically, when setting the boundary load loading mode, the well point measured value S and the predicted value x have the following relationship:

[0092] S i =A i x i +e i

[0093] Where [A] is the coefficient matrix, [S] is the measured stress matrix of the well point, [x] is the predicted value matrix, and e is the error between the measured value and the predicted value.

[0094] When setting the boundary load loading method, the difference function between the well point predicted value and the measured value is used as the objective function. When the accuracy of the objective function reaches the preset requirements, the reasonable boundary conditions are determined.

[0095]

[0096] M indicates a preset requirement.

[0097] Through finite element calculation, the current geostress distribution characteristics of the study area are obtained, including the direction and value of the maximum horizontal principal stress, the minimum horizontal principal stress, the vertical principal stress and the horizontal stress difference.

[0098] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and / or characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance, characterized in that: The following steps are involved: Construct geological structure model based on stratigraphic division and attribute assignment; The geological structure model is converted into a mechanical model based on material properties and structural properties, and the three-dimensional heterogeneous geomechanical property modeling of the formation is completed through single-point test analysis, single well logging interpretation, and plane distribution simulation, and a three-dimensional heterogeneous rock mechanical parameter model is generated; Use modeling software to import the established three-dimensional heterogeneous rock mechanics parameter model, assign corresponding rock mechanics parameters to geological units, mesh the imported model according to the finite element division principle, and generate a mesh mathematical model; The three-dimensional heterogeneous rock mechanics parameter model is used as the parameter model for ground stress prediction, and the initial value of the boundary condition is determined according to the regional structural analysis. The ground stress data of a single well test is used as the constraint condition to set the boundary load loading method. Through finite element calculation, the current distribution characteristics of ground stress in the study area are obtained.

2. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 1, characterized in that: Single-point test analysis includes the following steps: Geological data collection: Collect geological data of the study area, including core description, well logging data, seismic data, and geochemical data; Rock mechanical properties analysis: laboratory testing based on core samples to obtain the mechanical parameters of the rock; Data recording and analysis: The data obtained from the test are recorded and statistically analyzed to evaluate the approximate range of rock mechanical parameters at that point.

3. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 1, characterized in that: Single well logging interpretation includes the following steps: Using the P-wave time difference, S-wave time difference and density data in the well logging data of the study area, Young's modulus and Poisson's ratio are calculated by the following formula; Among them, E d is Young's modulus; μ d is Poisson's ratio; ρ is rock density; Δt p is the longitudinal wave time difference; Δt s is the shear wave time difference; Combined with the core triaxial stress test data of the study area, the Young's modulus and Poisson's ratio after well logging correction in the study area were calculated. Based on the corrected Young's modulus and Poisson's ratio, the formation characteristics, rock properties and fluid content in the well are interpreted.

4. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 1, characterized in that: Plane distribution simulation includes the following steps: Collect well logs and seismic data in the study area; Use logging data and seismic data to make cross-well predictions and construct three-dimensional lithofacies models; Combining the elastic parameter constraints of 3D seismic attribute inversion and the rock mechanics parameter test values ​​of well points in different tectonic zones, anisotropic sequential Gaussian random simulation is performed to obtain the 3D inhomogeneous rock mechanics parameter field distribution map of the study area. The rock mechanical zoning of the study area is carried out according to the simulated rock mechanical parameter distribution map.

5. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 4, characterized in that: When setting the boundary load loading method, the measured value S of the well point and the predicted value x have the following relationship: S i =A i x i +e i Where [A] is the coefficient matrix, [S] is the measured stress matrix of the well point, [x] is the predicted value matrix, and e is the error between the measured value and the predicted value.

6. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 5, characterized in that: When setting the boundary load loading method, the difference function between the well point predicted value and the measured value is used as the objective function. When the accuracy of the objective function reaches the preset requirements, the reasonable boundary conditions are determined.

7. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 6, characterized in that: The objective function formula is as follows:

8. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 7, characterized in that: The current geostress distribution characteristics include the maximum horizontal principal stress, the minimum horizontal principal stress, the vertical principal stress, and the direction and value of the horizontal stress difference.

9. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 8, characterized in that: Stratigraphic division includes division based on geological age, lithology, and sedimentary environment.

10. The method for constructing a quantitative relationship chart based on fault characteristics and stress disturbance according to claim 9, characterized in that: When meshing the model, three-node triangular elements are used to divide the fault and its surrounding areas into mesh units smaller than the preset area.

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