Method and system for determining fault planes using stratigraphic gradient and dip curvature

Abstract

This invention provides a method and system for determining fault planes using stratigraphic gradients and dip curvature, belonging to the field of petroleum exploration. The method includes: determining multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes a fault plane; obtaining cross sections of multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip and strike of each local surface model to determine the true curvature of the multiple cross sections; and determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the true curvature of the multiple cross sections. This invention solves the technical problem of existing technologies being unable to accurately determine the curvature of fault planes, thus failing to accurately determine fault planes, and improves the accuracy of fault plane determination.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and more specifically to a method and system for determining fault planes using stratigraphic gradient and dip curvature. Background Technology

[0002] In oil exploration, a crucial issue affecting oil and gas field development is fault structure. Current technologies commonly employ two methods: First, conventional 3D seismic interpretation. Conventional 3D seismic interpretation is primarily conducted on vertical seismic profiles. It requires interpreting each seismic line within the work area line by line to determine the planar distribution of faults and stratigraphic features, thus enabling manual analysis, judgment, and interpretation on the plane. However, this method is cumbersome and requires manual analysis, making it difficult to accurately determine fault planes.

[0003] The second method uses curvature attributes to describe the geometric variations of geological bodies. Curvature attributes correspond to the degree of bending of seismic reflectors and are sensitive to the bending, folding, fractures, and faults of rock strata, making them an effective means of finding stratigraphic structural features. In 2001, Roberts detailed the basic theory of curvature attributes and proposed the first-generation curvature analysis method—the calculation and workflow of surface curvature attributes. This demonstrated that curvature attributes are highly effective in extracting structural geometric features such as fault and fracture orientations, laying the foundation for the promotion and application of curvature attributes in the structural interpretation of seismic data. In 2006, Al-Dossary and Marfurt utilized the spatial orientation information contained in seismic data volumes to obtain the second-generation curvature analysis method—volume curvature attributes. Based on this, they used wavenumber Fourier transform to achieve multi-scale analysis of volume curvature attributes. Common curvatures include mean curvature, Gaussian curvature, maximum curvature, minimum curvature, maximum positive curvature, and minimum negative curvature. However, these curvatures are not true fault plane curvatures and cannot simultaneously determine the boundaries of fault planes, thus failing to accurately determine fault planes. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for determining fault planes using stratigraphic gradient and dip curvature. This method utilizes seismic data of the target layer to determine the stratigraphic gradient and true curvature of a cross section; and accurately determines the fault plane in the target layer based on the stratigraphic gradient and true curvature of the cross section. This invention fundamentally solves the technical problem of existing technologies being unable to accurately determine fault plane curvature, thus improving the accuracy of fault plane determination.

[0005] To achieve the above objectives, embodiments of the present invention provide a method and system for determining fault planes using stratigraphic gradients and dip curvature. The method includes: determining multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes fault planes; obtaining cross sections of multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model to determine the true curvature of the cross sections of the multiple local surface models; determining the strike of each local surface model based on the dip of each local surface model; and determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross sections of the multiple local surface models.

[0006] Optionally, determining multiple stratigraphic gradients corresponding to multiple local surface models based on the seismic data of the target layer includes: establishing a three-dimensional model of the target layer based on the seismic data of the target layer; determining the multiple local surface models based on the three-dimensional model of the target layer; and determining multiple stratigraphic gradients corresponding to the multiple local surface models based on the multiple local surface models.

[0007] Optionally, the seismic data includes time-domain horizons, line numbers, and trace numbers, as well as P-wave velocity curves. The step of establishing a three-dimensional model of the target layer based on the seismic data of the target layer includes: determining the depth-domain horizon of the target layer based on the time-domain horizons and the P-wave velocity curves of the target layer; and mapping the depth-domain horizons, line numbers, and trace numbers of the target layer onto a three-dimensional coordinate system to establish the three-dimensional model of the target layer.

[0008] Optionally, determining the depth domain level h of the target layer based on the time domain level (time) of the target layer and the P-wave velocity curve (v) includes:

[0009] Optionally, determining the plurality of local surface models based on the target layer 3D model includes: obtaining a plurality of center points on the target layer 3D model and a plurality of surface elements corresponding to the plurality of center points, wherein each surface element includes a plurality of 3D coordinate points; and determining the plurality of local surface models based on the plurality of 3D coordinate points of each surface element.

[0010] Optionally, determining the multiple formation gradients corresponding to the multiple local surface models includes: determining multiple omnidirectional directional derivatives of the center point in each local surface model based on each local surface model; and determining the directional derivative with the largest absolute value among the multiple omnidirectional directional derivatives of the center point as the formation gradient of each local surface model.

[0011] Optionally, the method further includes: determining the tendency of each local surface model by mapping the stratigraphic gradient of the plurality of local surface models onto two-dimensional coordinates in the three-dimensional coordinate system as the tendency of each local surface model.

[0012] Optionally, determining the orientation of each local surface model based on its inclination includes: determining the direction perpendicular to the inclination of each local surface model as the orientation of each local surface model.

[0013] Optionally, the step of obtaining the cross sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, and determining the true curvature of the cross sections of the multiple local surface models, includes: cutting along the z-axis direction in the three-dimensional coordinate system and in a direction parallel to the stratigraphic gradient of each local surface model, and determining the intersection line with each local surface model as the cross section of each local surface model; and determining the true curvature of the multiple cross sections with respect to the dip based on the cross sections of each local surface model.

[0014] Optionally, determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models includes: determining the stratigraphic gradient with the largest value among the multiple stratigraphic gradients corresponding to the multiple local surface models as the stratigraphic gradient of the fault plane; determining the multiple three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane as the multiple midpoints of the fault plane; determining the connecting line of the multiple midpoints of the fault plane along the orientation of the local surface models as the centerline of the fault plane; determining the orientation of the local surface model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients as the orientation of the fault plane; and determining the multiple three-dimensional coordinate points corresponding to the maximum positive curvature and minimum negative curvature of the cross-sections of the multiple local surface models as the boundaries of the fault plane.

[0015] Accordingly, the present invention also provides a system for determining fault planes using stratigraphic gradients and dip curvature. The system includes: a first determining module, configured to determine multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes fault planes; a second determining module, configured to obtain cross-sections of multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, thereby determining the true curvature of the cross-sections of the multiple local surface models; a third determining module, configured to determine the strike of each local surface model based on the dip of each local surface model; and a fourth determining module, configured to determine fault planes in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-sections of the multiple local surface models.

[0016] Optionally, the second determining module is further configured to determine the tendency of each local surface model by mapping the stratigraphic gradient of the plurality of local surface models onto two-dimensional coordinates in the three-dimensional coordinate system as the tendency of each local surface model.

[0017] Optionally, the third determining module is used to determine the orientation of each local surface model based on the inclination of each local surface model, which includes: determining the direction perpendicular to the inclination of each local surface model as the orientation of each local surface model.

[0018] Optionally, the second determining module is used to obtain the cross sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, and to determine the true curvature of the cross sections of the multiple local surface models includes: cutting along the z-axis direction in the three-dimensional coordinate system and the direction parallel to the stratigraphic gradient of each local surface model, and determining the intersection line with each local surface model as the cross section of each local surface model; and determining the true curvature of the multiple cross sections with respect to the dip based on the cross sections of each local surface model.

[0019] Optionally, the fourth determining module is used to determine the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models. This includes: determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models. Layer gradient; multiple three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane are determined as multiple midpoints of the fault plane; the connecting line of the multiple midpoints of the fault plane along the direction of the local surface model is determined as the centerline of the fault plane; the direction of the local surface model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients is determined as the direction of the fault plane; and based on the true curvature of the cross section of the multiple local surface models, multiple three-dimensional coordinate points corresponding to the maximum positive curvature and minimum negative curvature of the cross section of the local surface model are determined as the boundaries of the fault plane.

[0020] Through the above technical solution, this method utilizes seismic data of the target layer to determine multiple stratigraphic gradients corresponding to multiple local surface models; based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, it obtains the cross-sections of the multiple local surface models to determine the true curvature of the cross-sections of the multiple local surface models; based on the dip of each local surface model, it determines the strike of each local surface model; and based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-sections of the multiple local surface models, it determines the fault plane in the target layer. Therefore, this invention fundamentally solves the technical problem of existing technologies being unable to accurately determine the curvature of fault planes, thus failing to accurately determine fault planes, and improves the accuracy of fault plane determination.

[0021] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a flowchart of a method for determining a fault plane provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the target layer structure provided in an embodiment of the present invention;

[0025] Figure 3 This is a flowchart of determining the formation gradient of a local surface model provided in an embodiment of the present invention;

[0026] Figure 4 This is a diagram of the surface structure of center points A, B, and C provided in an embodiment of the present invention;

[0027] Figure 5 These are the three fitted surface models provided in the embodiments of the present invention;

[0028] Figure 6 This is the local surface model corresponding to the center point B provided in the embodiment of the present invention;

[0029] Figure 7 This is the target layer of other types of structures provided in the embodiments of the present invention;

[0030] Figure 8 This is a schematic diagram of the cross section of the local surface model at point A provided in an embodiment of the present invention;

[0031] Figure 9 This is a flowchart of determining the fracture surface provided in an embodiment of the present invention;

[0032] Figure 10 It is the target layer containing multiple fracture surfaces provided in the embodiments of the present invention;

[0033] Figure 11 This is a rendering of the cross-sectional area provided in an embodiment of the present invention. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0035] Figure 1 This is a flowchart of a method for determining a fault plane provided by an embodiment of the present invention. The method includes the following steps S100-S103.

[0036] S100. Based on the seismic data of the target layer, determine multiple stratigraphic gradients corresponding to multiple local surface models.

[0037] The target layer includes the fracture surface.

[0038] Specifically, refer to Figure 2 This is a schematic diagram of the target layer provided in an embodiment of the present invention. The target layer is a stratum of interest during seismic exploration, and the target layer includes fault planes. This invention is used to accurately determine the extent and direction of the fault planes of the target layer based on the target layer.

[0039] Furthermore, Figure 3 This is a flowchart of determining the stratigraphic gradient of a local surface model according to an embodiment of the present invention. The step of determining multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of the target layer further includes the following steps S1001-S1003.

[0040] S1001. Based on the seismic data of the target layer, a three-dimensional model of the target layer is established.

[0041] Furthermore, establishing a three-dimensional model of the target layer based on the seismic data of the target layer includes: determining the depth-domain horizon of the target layer based on the time-domain and P-wave velocity curves of the target layer; and mapping the depth-domain horizon, line number, and trace number of the target layer onto a three-dimensional coordinate system to establish the three-dimensional model of the target layer. The seismic data includes the time-domain horizon, line number, trace number, and P-wave velocity curves.

[0042] Specifically, seismic data of the target layer is acquired, including time-domain horizons, line numbers, trace numbers, and P-wave velocity profiles. To facilitate the identification of the target layer within its stratigraphic region, the time-domain horizons are converted to depth-domain horizons. Then, the depth-domain horizons, line numbers, and trace numbers are mapped onto a three-dimensional coordinate system to establish a three-dimensional model of the target layer. Specifically, the established three-dimensional model of the target layer can be found in [reference needed]. Figure 2 .

[0043] Further, determining the depth domain level h of the target layer based on the time-domain level (time) and the P-wave velocity curve (v) includes:

[0044] Specifically, the wave one-way propagation time can be obtained from the time-domain horizon (time) in the seismic data of the target layer. Furthermore, the propagation velocity of the P-wave can be obtained from the P-wave velocity curve v, and the average propagation velocity of the P-wave can also be calculated from the waveform curve. Therefore, the depth domain layer h of the target layer can be calculated using the above formula.

[0045] S1002. Determine the plurality of local surface models based on the three-dimensional model of the target layer.

[0046] Further, determining the plurality of local surface models based on the target layer 3D model includes: obtaining a plurality of center points on the target layer 3D model and a plurality of surface elements corresponding to the plurality of center points, wherein each surface element includes a plurality of 3D coordinate points; and determining a plurality of local surface models based on the plurality of 3D coordinate points of each surface element.

[0047] Specifically, with Figure 2 Taking the target layer as an example, multiple center points are obtained on the target layer, such as... Figure 2 The example shown is for obtaining three center points (A, B, C). Of course, any number of center points at any position can also be obtained. This embodiment of the invention is only for clearly explaining the embodiments of the invention.

[0048] refer to Figure 4 The diagram shows multiple three-dimensional coordinate points, such as 3×3, 5×5, or even more, scattered around center points A, B, and C. To improve the accuracy of the surface model, this embodiment uses a 5×5 grid (i.e., 25 three-dimensional coordinate points) as an example. The surface element of center point A (B or C) is the grid connected by the 5×5 three-dimensional coordinate points of center point A (B or C), and the center point is the center of the 5×5 scattered grid points.

[0049] After obtaining multiple 3D coordinate points, three surface elements are obtained around the center points A, B, and C, resulting in a total of three surface elements. Three local surface models (i.e., the target layer is divided into three local surfaces) can be fitted using the multiple 3D coordinate points on these three surface elements. Given the multiple 3D coordinate points of each surface element, a quadratic polynomial is used to fit the local surface of each surface element, thus fitting three local surfaces. The specific fitting method can be achieved using the following formula. Solving the following system of linear matrix equations yields the polynomial coefficients a, b, c, d, e, and f, where the linear coefficients are all constants.

[0050]

[0051] Therefore, for each surface element, 25 three-dimensional coordinate points are obtained. Thus, 'n' in the above formula corresponds to 25 sets of data. The polynomial coefficients can be solved using the matrix formula, and then a local surface model for each center point can be fitted. The three fitted surface models can be used as a reference. Figure 5 .

[0052] S1003. Based on the multiple local surface models, determine the multiple formation gradients corresponding to the multiple local surface models.

[0053] Further, determining the multiple formation gradients corresponding to the multiple local surface models based on the multiple local surface models includes: determining multiple omnidirectional directional derivatives of the center point in each local surface model based on each local surface model; and determining the directional derivative with the largest absolute value among the multiple omnidirectional directional derivatives of the center point as the formation gradient of each local surface model.

[0054] Specifically, this embodiment of the invention will still use three surface models as an example for explanation. After fitting three local surface models, multiple stratigraphic gradients at the center point of each local surface model are determined. Taking the local surface model corresponding to center point A as an example, the directional derivatives (0-360°) of multiple three-dimensional coordinate points in the two-dimensional plane are calculated. Specifically, existing methods for solving directional derivatives can be used. For example, multiple directional derivatives can be calculated for center point A. If one azimuth derivative is calculated for every 1°, 360 directional derivatives can be obtained.

[0055] The specific method for solving the directional derivative can utilize the existing directional derivative of the two-dimensional plane, specifically using the following formula: Where l represents a ray drawn along each three-dimensional coordinate point, and the angle between ray l and the x-axis of the two-dimensional coordinate plane in the three-dimensional coordinate system is α.

[0056] For the local surface model corresponding to center point A, a total of 360 azimuth derivatives were obtained. The formation gradient of the local surface model corresponding to center point A was then further calculated. The formation gradient with the largest absolute value among the 360 ​​azimuth derivatives was determined as the formation gradient grad of the local surface model corresponding to center point A. Specifically, the following formula can be used: The direction of the formation gradient grad indicates the direction in which the directional derivative of the function is largest at that point, and its absolute value is equal to the maximum value of the directional derivative.

[0057] The above method can be used to solve for the formation gradient of the local surface model corresponding to center point A. Similarly, the formation gradient of the local surface model corresponding to center point B or center point C can be solved separately using the same method, which will not be repeated here.

[0058] S101. Based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, obtain the cross-sections of the local surface models of the multiple local surface models to determine the true curvature of the cross-sections of the multiple local surface models.

[0059] Furthermore, the method also includes determining the tendency of each local surface model by mapping the stratigraphic gradient of the plurality of local surface models onto two-dimensional coordinates in the three-dimensional coordinate system as the tendency of each local surface model.

[0060] Specifically, refer to Figure 6Taking the local surface model corresponding to center point B as an example, the principle for determining the dip and orientation of other local surface models is the same. Assuming that the stratigraphic gradient of the local surface model corresponding to center point B, obtained from step S1003 above, is equal to 2 (i.e., the directional derivative is at its maximum value of 2) and its azimuth is 12° (i.e., α = 12°), then the direction of mapping the stratigraphic gradient (which can be understood as the direction of the maximum slope of the local surface model corresponding to center point B) onto the two-dimensional coordinate system (x, y) of the three-dimensional coordinates is determined as the dip of the local surface model corresponding to center point B (e.g., ...). Figure 6 In this context, 's' represents the tendency, and the direction perpendicular to the tendency of the local surface model is defined as the orientation of the local surface model (e.g., ...). Figure 6 In this context, 't' represents the orientation, which can be used to determine the direction of the fault plane's extension.

[0061] refer to Figure 6 Let's continue with the example of the local surface model corresponding to center point B. The inclination s of this local surface model maps to the vector s′ on the two-dimensional coordinate plane, and the angle between vector s′ and the x-coordinate axis... Based on the orientation t of the local surface model, determine the vector ′ that the orientation of each local surface maps to in the two-dimensional coordinate (x, y) plane of the three-dimensional coordinate system, and the angle between the vector ′ and the x-coordinate axis. The included angle of the local surface model can be calculated using existing formulas, i.e. Where atan2 represents the arctangent of the four quadrants, and d and e represent the coefficients of the polynomial of each local surface model, which have been obtained in step S1002 above when solving each local surface model and are known values.

[0062] The above method can be used to calculate... It is 12°. The angle is 102°. Similarly, the angle between the local surface models corresponding to center point A and center point C can also be calculated. It is 12°. It is 102°. For other types of fault planes, such as... Figure 7 For the structure in the model, the corresponding local surface model corresponding to the center point D can be calculated using the method described above. If it is -43°, then It is 47°.

[0063] Further, the step of obtaining the cross sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, and determining the true curvature of the cross sections of the multiple local surface models, includes: cutting along the z-axis direction in the three-dimensional coordinate system and in a direction parallel to the stratigraphic gradient of each local surface model, and determining the intersection line with each local surface model as the cross section of each local surface model; and determining the true curvature of the multiple cross sections with respect to the dip based on the cross sections of each local surface model.

[0064] Specifically, after calculating the stratigraphic gradient of the local surface model at each of the three center points using the method described above, the model is cut along the z-axis direction in the three-dimensional coordinate system and in a direction parallel to the stratigraphic gradient of each local surface model. The intersection line with each local surface model is determined as the transverse section of each local surface model. (Refer to...) Figure 6 The solid line PQ in the diagram represents the transverse section of the local surface model at center point B. Figure 8 The dashed lines s1s2 in the diagram represent the transverse sections of the local surface model at center point A. The method for determining the transverse sections of the local surface model at center point C is similar and will not be repeated here.

[0065] After determining the transverse sections of the local surface models corresponding to the three center points, the true curvature corresponding to each transverse section is further determined. (In existing technologies, the curvature is calculated for the entire surface, while in this invention, the surface is decomposed into multiple surfaces, and the curvature of the transverse section of each surface model is calculated separately. Therefore, the curvature of each three-dimensional coordinate point on the transverse section can be obtained, and this curvature is the true curvature.) The specific method for determining the transverse section of each local surface model is as follows:

[0066] Rotating the x, y plane coordinates to a coordinate system denoted by t and s causes the local surface function to degenerate into a parabolic function. The specific formula derivation is as follows:

[0067] x=scosφ dip ,y=ssinφ dip .

[0068]

[0069]

[0070] Therefore, it can be seen from the above function that the local surface function has been transformed into a linear equation in two variables, degenerating into a parabolic function. Among them, a, b, c, d, e, and f represent the polynomial coefficients of the transverse section of each local surface model, and the values ​​of these parameters have been obtained in step S1002.

[0071] After obtaining the function of the transverse section of each local surface model, the curvature equation is solved using existing techniques, and the true curvature of the transverse section of the local surface model is further solved using the above formula.

[0072] The above method can solve for the true curvature of the cross section of the local surface model of each local surface model. Compared with the existing technology, which can only solve for the curvature of the surface, the embodiments of the present invention convert it into solving for the true curvature of the cross section of the local surface model of the local surface model. It can truly solve for the true curvature of the surface model, laying the foundation for the accurate determination of the boundary of the fault plane. For details on the specific application effect, please refer to the following content.

[0073] S102. Determine the orientation of each local surface model based on its tendency.

[0074] Further, determining the orientation of each local surface model based on the inclination of each local surface model includes: determining the direction perpendicular to the inclination of each local surface model as the orientation of each local surface model.

[0075] For details on determining the direction of each local surface model, please refer to step S101, which will not be repeated here.

[0076] S103. Determine the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross section of the multiple local surface models.

[0077] Further to, Figure 9 A flowchart for determining the fault plane. The method further includes determining the centerline, strike, and boundary of the fault plane based on multiple stratigraphic gradients corresponding to the multiple local surface models and the true curvature of the cross sections of the multiple local surface models. The method also includes the following steps S1020-S1025.

[0078] S1020. The stratigraphic gradient with the largest value among the multiple stratigraphic gradients corresponding to the multiple local surface models is determined as the stratigraphic gradient of the fault plane.

[0079] Specifically, the stratigraphic gradients of the three local surface models have been calculated in the above steps. Here, we will further determine the stratigraphic gradient of the fault plane. The stratigraphic gradients of these three local surface models are compared with each other. For example, the stratigraphic gradient of the local surface model at center point A is 0.89, the stratigraphic gradient of the local surface model at center point B is 2, and the stratigraphic gradient of the local surface model at center point C is 0.97. Therefore, the stratigraphic gradient with the largest value among the three local surface models can be determined to be 2, which corresponds to the local surface model at center point B. Multiple three-dimensional coordinate points are taken along the gradient direction of center point B. The stratigraphic gradient with the largest value among these multiple three-dimensional coordinate points is determined as the stratigraphic gradient of the fault plane. Assuming that the three-dimensional coordinate point corresponding to the largest gradient value among the multiple three-dimensional coordinate points along the gradient direction of center point B is center point B (or possibly other three-dimensional coordinate points along center point B), then center point B is determined as the stratigraphic gradient of the fault plane.

[0080] S1021. Determine multiple three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane as multiple midpoints of the fault plane.

[0081] Specifically, after determining that the stratigraphic gradient of the local surface model at the center point B is the stratigraphic gradient of the fault plane, the centerline of the fault plane is further determined. (Reference) Figure 5 It can be seen that the stratigraphic gradient corresponding to the point at the common midline point B along the direction of the surface model is approximately equal to the stratigraphic gradient corresponding to the common midline point B. Therefore, multiple midpoints of the fault plane can be determined.

[0082] S1022 defines the line connecting multiple midpoints of the fault plane along the direction of the local surface model as the centerline of the fault plane.

[0083] Specifically, after determining multiple midpoints of the fault plane, the connecting line of the multiple midpoints of the fault plane along the direction t of the local surface model is determined as the centerline of the fault plane.

[0084] S1024. The strike of the local curve model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients is determined as the strike of the fault plane.

[0085] Specifically, after determining the centerline of the fault plane, the strike of the fault plane is further determined. In step S1020, among the three local surface models, it has been determined that the stratigraphic gradient value of the local surface model corresponding to the center point B is the largest. Therefore, the strike t of the local surface model corresponding to the center point B is further determined as the strike of the fault plane.

[0086] S1025. Based on the true curvature of the cross-sections of the multiple local surface models, determine that the true curvature of the cross-sections of the local surface models is the boundary of the fault plane, which is the multiple three-dimensional coordinate points corresponding to the maximum positive curvature and the minimum negative curvature.

[0087] Specifically, for example, assuming the true curvature of the three cross-sections of three local surfaces is as follows: the true curvature of the cross-section corresponding to the center point A is 0.247, and multiple three-dimensional coordinate points with corresponding true curvatures can be determined along the direction t of the center point A; the curvature of the cross-section corresponding to the center point B is -0.038, approximately 0 (its cross-section is approximately a straight line, therefore the curvature around the center point B is still approximately 0). Similarly, multiple three-dimensional coordinate points with corresponding true curvatures approximately 0 can be determined along the direction t of the center point B; the negative curvature of the cross-section corresponding to the center point C at the center point C is -0.232, and multiple three-dimensional coordinate points with corresponding true curvatures approximately -0.232 can be determined along the direction t of the center point C. The multiple three-dimensional coordinate points corresponding to the maximum positive curvature are defined as one boundary of the fault plane, and the multiple three-dimensional coordinate points corresponding to the minimum negative curvature are defined as another boundary of the fault plane.

[0088] The above method can accurately determine the centerline of the fault plane and the two boundaries of the fault plane. Compared with the prior art, which can only determine one boundary of the fault plane, the embodiments of the present invention can accurately determine both boundaries of the fault plane and the centerline of the fault plane, thus improving the accuracy of fault plane determination. (Reference) Figure 10 It is the target layer containing multiple fracture surfaces. Figure 11 This is a diagram of the fracture surface obtained by the method according to the present invention (i.e., Figure 10 (A top view of the fracture surface). Each fault plane can be precisely defined down to every point, which is more accurate and detailed than manual interpretation of fault planes (interpreting the fault with ten lines and then interpolating to a fault curve).

[0089] Through the above technical solution, this method utilizes seismic data of the target layer to determine multiple stratigraphic gradients corresponding to multiple local surface models; based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, it obtains the cross-sections of the multiple local surface models to determine the true curvature of the cross-sections of the multiple local surface models; based on the dip of each local surface model, it determines the strike of each local surface model; and based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-sections of the multiple local surface models, it determines the fault plane in the target layer. Therefore, this invention fundamentally solves the technical problem of existing technologies being unable to accurately determine the curvature of fault planes, thus failing to accurately determine fault planes, and improves the accuracy of fault plane determination.

[0090] Conventional curvature-based fault prediction suffers from location deviation. Maximum curvature and maximum positive curvature reflect anticline structures and fault hanging wall boundaries, while minimum curvature and minimum negative curvature reflect syncline structures and fault footwall boundaries. Both are offset from the fault core, hindering fault detection. Therefore, this invention fundamentally solves the technical problem of existing technologies being unable to accurately determine fault plane curvature, thus improving the accuracy of fault plane determination.

[0091] On the other hand, embodiments of the present invention also provide a system for determining fault planes, the system comprising: a first determining module, configured to determine multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes fault planes; a second determining module, configured to obtain cross-sections of multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, thereby determining the true curvature of the cross-sections of the multiple local surface models; a third determining module, configured to determine the strike of each local surface model based on the dip of each local surface model; and a fourth determining module, configured to determine fault planes in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-sections of the multiple local surface models.

[0092] The first determining module, the second determining module, the third determining module, and the fourth determining module can be the same determining module or different determining modules. For details regarding the determination of the fault plane and its effects, please refer to the relevant description of the above-described method for determining the fault plane, which will not be repeated here.

[0093] Furthermore, the second determining module is also used to determine the tendency of each local surface model by mapping the direction of the formation gradient of the plurality of local surface models onto the two-dimensional coordinates in the three-dimensional coordinate system as the tendency of each local surface model.

[0094] For details regarding the determination of the tendency of each local surface model and its effects, please refer to the relevant explanation of the above-mentioned method for determining the fault plane, which will not be repeated here.

[0095] Furthermore, the third determining module, used to determine the orientation of each local surface model based on the inclination of each local surface model, includes: determining the direction perpendicular to the inclination of each local surface model as the orientation of each local surface model.

[0096] For details regarding the determination of the orientation of each local surface model and its effects, please refer to the relevant explanation of the above-mentioned method for determining the fault plane, which will not be repeated here.

[0097] Further, the second determining module is used to obtain the cross sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, and to determine the true curvature of the cross sections of the multiple local surface models includes: cutting along the z-axis direction in the three-dimensional coordinate system and the direction parallel to the stratigraphic gradient of each local surface model, and determining the intersection line with each local surface model as the cross section of each local surface model; and determining the true curvature of the multiple cross sections with respect to the dip based on the cross sections of each local surface model. The fourth determining module is used to determine the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models. This includes: determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models. The method involves: determining multiple three-dimensional coordinate points corresponding to the stratigraphic gradients of the fault plane as multiple midpoints of the fault plane; determining the connecting line of the multiple midpoints of the fault plane along the direction of the local surface model as the centerline of the fault plane; determining the direction of the local surface model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients as the direction of the fault plane; and determining multiple three-dimensional coordinate points corresponding to the maximum positive curvature and minimum negative curvature of the cross-section of the local surface model as the boundaries of the fault plane based on the true curvature of the cross-section of the multiple local surface models.

[0098] For details regarding the determination of the fault plane's strike, median, and boundary, as well as its effects, please refer to the relevant descriptions of the fault plane determination method described above, which will not be repeated here. Those skilled in the art will understand that the embodiments of this application can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0099] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0100] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0101] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0102] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0103] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0104] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0105] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0106] The above are merely embodiments of the present invention and are not intended to limit the scope of the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for determining fault planes using stratigraphic gradient and dip curvature, characterized in that, The method includes: Based on the seismic data of the target layer, multiple stratigraphic gradients corresponding to multiple local surface models are determined, wherein the target layer includes fault planes; Based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, the cross-sections of the multiple local surface models are obtained to determine the true curvature of the cross-sections of the multiple local surface models. Based on the tendency of each local surface model, determine the orientation of each local surface model; and Based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models, the fault planes in the target layer are determined.

2. The method according to claim 1, characterized in that, The process of determining multiple stratigraphic gradients corresponding to multiple local surface models based on seismic data of the target layer includes: The three-dimensional model of the target layer is established based on the seismic data of the target layer. Based on the target layer 3D model, determine the plurality of local surface models; and Based on the multiple local surface models, multiple formation gradients corresponding to the multiple local surface models are determined.

3. The method according to claim 2, characterized in that, The seismic data includes time-domain horizons, line numbers, trace numbers, and P-wave velocity profiles. The step of establishing a three-dimensional model of the target layer based on the seismic data of the target layer includes: The depth domain level of the target layer is determined based on the time-domain layer position and the P-wave velocity curve; and The depth domain layer, line number, and channel number of the target layer are mapped onto a three-dimensional coordinate system to establish a three-dimensional model of the target layer.

4. The method according to claim 3, characterized in that, According to the time domain level of the target layer time With the longitudinal wave velocity curve v Determine the depth domain layer of the target layer. include: 。 5. The method according to claim 2, characterized in that, The step of determining the plurality of local surface models based on the target layer 3D model includes: Obtain multiple center points on the target layer 3D model and multiple polygons corresponding to the multiple center points, wherein each polygon includes multiple 3D coordinate points; and The plurality of local surface models are determined based on the plurality of three-dimensional coordinate points of each of the plurality of surface elements.

6. The method according to claim 5, characterized in that, The step of determining the multiple formation gradients corresponding to the multiple local surface models includes: Based on each local surface model, determine multiple omnidirectional directional derivatives of the center point in each local surface model; and The directional derivative with the largest absolute value among the multiple directional derivatives at the center point is determined as the formation gradient of each local surface model.

7. The method according to claim 1, characterized in that, The method further includes determining the tendency of each local curve model in the following manner: The direction of the formation gradient mapping of the plurality of local surface models onto the two-dimensional coordinates in the three-dimensional coordinate system is determined as the inclination of each local surface model.

8. The method according to claim 7, characterized in that, Determining the orientation of each local surface model based on its tendency includes: The direction perpendicular to the inclination of each local surface model is determined as the orientation of each local surface model.

9. The method according to claim 1, characterized in that, The step of obtaining the cross-sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, and determining the true curvature of the cross-sections of the multiple local surface models, includes: Cut along the z-axis in the three-dimensional coordinate system and along the direction parallel to the stratigraphic gradient of each local surface model, and determine the intersection line with each local surface model as the transverse section of each local surface model; and Based on the cross-section of each local surface model, determine the true curvature of the plurality of cross-sections with respect to the inclination.

10. The method according to claim 9, characterized in that, The step of determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models includes: The stratigraphic gradient with the largest value among the multiple stratigraphic gradients corresponding to the multiple local surface models is determined as the stratigraphic gradient of the fault plane; Multiple three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane are determined as multiple midpoints of the fault plane. The line connecting multiple midpoints of the fault plane along the direction of the local surface model is determined as the centerline of the fault plane. The strike of the local curve model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients is determined as the strike of the fault plane; and Based on the true curvature of the cross-sections of the multiple local surface models, the multiple three-dimensional coordinate points corresponding to the maximum positive curvature and minimum negative curvature of the true curvature of the cross-sections of the local surface models are determined as the boundaries of the fault plane.

11. A system for determining fault planes using stratigraphic gradient and dip curvature, characterized in that, The system includes: The first determining module is used to determine multiple stratigraphic gradients corresponding to multiple local surface models based on the seismic data of the target layer, wherein the target layer includes fault planes; The second determining module is used to obtain the cross-sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, so as to determine the true curvature of the cross-sections of the multiple local surface models. The third determining module is used to determine the orientation of each local surface model based on the tendency of each local surface model; and The fourth determining module is used to determine the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross section of the multiple local surface models.

12. The system according to claim 11, characterized in that, The second determining module is further configured to determine the tendency of each local surface model in the following manner: The direction of the formation gradient mapping of the plurality of local surface models onto the two-dimensional coordinates in the three-dimensional coordinate system is determined as the inclination of each local surface model.

13. The system according to claim 12, characterized in that, The third determining module is used to determine the orientation of each local surface model based on the tendency of each local surface model, including: The direction perpendicular to the inclination of each local surface model is determined as the orientation of each local surface model.

14. The system according to claim 11, characterized in that, The second determining module is used to obtain the cross-sections of the multiple local surface models based on the multiple stratigraphic gradients corresponding to the multiple local surface models and the dip of each local surface model, so as to determine the true curvature of the cross-sections of the multiple local surface models, including: Cut along the z-axis in the three-dimensional coordinate system and along the direction parallel to the stratigraphic gradient of each local surface model, and determine the intersection line with each local surface model as the transverse section of each local surface model; and Based on the cross-section of each local surface model, determine the true curvature of the plurality of cross-sections with respect to the inclination.

15. The system according to claim 11, characterized in that, The fourth determining module is used to determine the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models, including: The step of determining the fault plane in the target layer based on the multiple stratigraphic gradients corresponding to the multiple local surface models, the orientation of each local surface model, and the true curvature of the cross-sections of the multiple local surface models includes: The stratigraphic gradient with the largest value among the multiple stratigraphic gradients corresponding to the multiple local surface models is determined as the stratigraphic gradient of the fault plane; Multiple three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane are determined as multiple midpoints of the fault plane. The line connecting multiple midpoints of the fault plane along the direction of the local surface model is determined as the centerline of the fault plane. The strike of the local curve model corresponding to the stratigraphic gradient with the largest value among the multiple stratigraphic gradients is determined as the strike of the fault plane; and Based on the true curvature of the cross-sections of the multiple local surface models, the multiple three-dimensional coordinate points corresponding to the maximum positive curvature and minimum negative curvature of the true curvature of the cross-sections of the local surface models are determined as the boundaries of the fault plane.

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