Method and system for determining fault plane by applying formation gradient and tendency curvature

Abstract

The embodiment of the invention provides a method and system for determining a fault plane by applying formation gradient and tendency curvature, and belongs to the field of oil exploration. The method comprises the steps that according to seismic data of a target stratum, multiple stratum gradients corresponding to multiple local curved surface models are determined, and the target stratum comprises a fault plane; according to the plurality of stratum gradients corresponding to the plurality of local curved surface models and the tendency and trend of each local curved surface model, obtaining cross section lines of the plurality of local curved surface models, so as to determine true curvatures of the plurality of cross section lines; and determining a fault plane in the target stratum according to the plurality of stratum gradients corresponding to the plurality of local curved surface models and the true curvatures of the plurality of cross section lines. The technical problem that the fault plane curvature cannot be accurately determined in the prior art so that the fault plane cannot be accurately determined is solved, and the accuracy of determining the fault plane is improved.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploration, and in particular to a method and a system for determining a fault plane by using formation gradient and dip curvature. Background Art

[0002] In oil exploration, a very important issue that affects the exploration and development of oil and gas fields is fault structure. The existing technology often uses the following two methods: the first is to use conventional 3D seismic interpretation. Conventional 3D seismic interpretation is basically carried out on a vertical seismic profile. It requires interpreting each survey line in the work area one by one to determine the plane distribution of faults and stratigraphic features, so as to use manual analysis, judgment and interpretation on the plane. However, this method is cumbersome and requires manual analysis to accurately determine the fault plane.

[0003] The second method is to use curvature attributes to describe the geometric changes of geological bodies. Curvature attributes correspond to the degree of curvature of seismic reflectors, and are sensitive to the bending, folds, cracks and faults of rock formations. They are an effective means of finding stratigraphic structural features. In 2001, Roberts elaborated on the basic theory of curvature attributes and proposed the calculation and workflow of the first generation of curvature analysis methods, namely, the curvature attributes of the plane, indicating that curvature attributes are very effective in extracting structural geometric features such as fault and crack orientation, laying the foundation for the promotion and application of curvature attributes in the structural interpretation of seismic data. In 2006, Al-Dossary and Marfurt used the spatial orientation information contained in the seismic data body to obtain the second generation of curvature analysis methods, namely, the volume curvature attributes, and on this basis, the multi-scale analysis of the volume curvature attributes was realized by using the Fourier transform of wavenumber division. Common curvatures include mean curvature, Gaussian curvature, maximum curvature, minimum curvature, maximum positive curvature and minimum negative curvature. However, these curvatures are not the curvature of the fault plane in the true sense, and the boundary of the fault plane cannot be determined at the same time, so the fault plane cannot be accurately determined. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a method and system for determining a fault plane using formation gradient and dip curvature, wherein the method uses seismic data of a target layer to determine the formation gradient and true curvature of a cross section; and accurately determines the fault plane in the target layer according to the formation gradient and true curvature of the cross section. The present invention fundamentally solves the technical problem that the prior art cannot accurately determine the curvature of the fault plane and thus cannot accurately determine the fault plane, and improves the accuracy of determining the fault plane.

[0005] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides a method and system for determining a fault plane using formation gradients and dip curvatures, the method comprising: determining a plurality of formation gradients corresponding to a plurality of local surface models according to seismic data of a target layer, wherein the target layer comprises a fault plane; obtaining cross-sections of a plurality of local surface models according to a plurality of formation gradients corresponding to the plurality of local surface models and the dip of each local surface model to determine the true curvature of the cross-sections of the plurality of local surface models; determining the strike of each local surface model according to the dip of each local surface model; and determining the fault plane in the target layer according to a plurality of formation gradients corresponding to the plurality of local surface models, the strike of each local surface model and the true curvature of the cross-sections of the plurality of local surface models.

[0006] Optionally, determining multiple formation 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 formation gradients corresponding to the multiple local surface models based on the multiple local surface models.

[0007] Optionally, the seismic data includes time domain layers, line numbers and track numbers, and longitudinal wave velocity curves, and establishing the three-dimensional model of the target layer based on the seismic data of the target layer includes: determining the depth domain layers of the target layer based on the time domain layers of the target layer and the longitudinal wave velocity curve; and mapping the depth domain layers, line numbers and track numbers of the target layer to a three-dimensional coordinate system to establish the three-dimensional model of the target layer.

[0008] Optionally, determining the depth domain layer h of the target layer according to the time domain layer time and the longitudinal wave velocity curve v comprises:

[0009] Optionally, determining the multiple local surface models based on the target layer three-dimensional model includes: obtaining multiple center points on the target layer three-dimensional model and multiple face elements corresponding to the multiple center points, wherein each face element includes multiple three-dimensional coordinate points; and determining the multiple local surface models based on the multiple three-dimensional coordinate points of each face element in the multiple face elements.

[0010] Optionally, determining 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.

[0011] Optionally, the method further comprises: determining the inclination of each local curved surface model by: determining the direction of the mapping of the stratigraphic gradients of the multiple local curved surface models on the two-dimensional coordinates in the three-dimensional coordinate system as the inclination of each local curved surface model.

[0012] Optionally, determining the direction of each local surface model according to the inclination of each local surface model includes: determining a direction on each local surface model that is perpendicular to the inclination of each local surface model as the direction of each local surface model.

[0013] Optionally, obtaining the cross-section lines of the multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-section lines 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 formation gradient of each local surface model, and determining the intersection line with the each local surface model as the cross-section line of each local surface model; and determining the true curvature of the multiple cross-section lines with respect to the inclination according to the cross-section line of each local surface model.

[0014] Optionally, determining the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models, the direction of each local surface model and the true curvature of the cross-section of the multiple local surface models includes: determining the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local surface models as the formation gradient of the fault plane; determining the multiple three-dimensional coordinate points corresponding to the formation 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 direction of the local surface model as the centerline of the fault plane; determining the direction of the local surface model corresponding to the formation gradient with the largest value among the multiple formation gradients as the direction of the fault plane; and determining, according to the true curvature of the cross-section of the multiple local surface models, the multiple three-dimensional coordinate points corresponding to the true curvature of the cross-section of the local surface model when the true curvature is the maximum positive curvature and the minimum negative curvature as the boundaries of the fault plane.

[0015] Correspondingly, the present invention also provides a system for determining fault planes using formation gradients and dip curvatures, the system comprising: a first determination module, for determining multiple formation gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes a fault plane; a second determination module, for acquiring cross-sections of multiple local surface models based on multiple formation 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; a third determination module, for determining the strike of each local surface model based on the dip of each local surface model; and a fourth determination module, for determining the fault plane in the target layer based on the multiple formation 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 determination module is further used to determine the inclination of each local surface model in the following manner: mapping the stratigraphic gradients of the multiple local surface models to a direction on a two-dimensional coordinate in the three-dimensional coordinate system is determined as the inclination of each local surface model.

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

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

[0019] Optionally, the fourth determination module is used to determine the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-section of the multiple local surface models, including: determining the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models, the strike of each local surface model, and the true curvature of the cross-section of the multiple local surface models, including: determining the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local surface models as the fault plane. layer gradient; determining a plurality of three-dimensional coordinate points corresponding to the formation gradient of the fault plane as a plurality of midpoints of the fault plane; determining a connecting line of the plurality of midpoints of the fault plane along the direction of the local curved surface model as the centerline of the fault plane; determining the direction of the local curved model corresponding to the formation gradient with the largest value among the plurality of formation gradients as the direction of the fault plane; and determining, based on the true curvature of the cross-section of the plurality of local curved surface models, a plurality of three-dimensional coordinate points corresponding to the true curvature of the cross-section of the local curved surface model with the maximum positive curvature and the minimum negative curvature as the boundaries of the fault plane.

[0020] Through the above technical solution, the method uses the seismic data of the target layer to determine multiple formation gradients corresponding to multiple local surface models; obtains the cross-sections of multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-sections of the multiple local surface models; determines the strike of each local surface model according to the inclination of each local surface model; and determines the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models and the strike of each local surface model and the true curvature of the cross-sections of the multiple local surface models. Therefore, the present invention fundamentally solves the technical problem that the prior art cannot accurately determine the curvature of the fault plane and thus cannot accurately determine the fault plane, and improves the accuracy of determining the fault plane.

[0021] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0023] Figure 1 is a flow chart of a method for determining a fault plane provided by an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the structure of the destination layer provided by an embodiment of the present invention;

[0025] Figure 3 is a flow chart of determining the formation gradient of a local surface model provided by an embodiment of the present invention;

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

[0027] Figure 5 are three curved surface models after fitting provided by an embodiment of the present invention;

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

[0029] Figure 7 It is a target layer of other types of structures provided by an embodiment of the present invention;

[0030] Figure 8 is a schematic cross-sectional view of a local surface model of point A provided by an embodiment of the present invention;

[0031] Fig. 9 is a flow chart of determining a fault plane provided by an embodiment of the present invention;

[0032] Fig.10 The target layer including multiple fault planes provided in an embodiment of the present invention;

[0033] Fig.11 It is an effect diagram of the fault plane provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0034] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

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

[0036] S100: Determine multiple formation gradients corresponding to multiple local surface models according to seismic data of a target layer.

[0037] Wherein, the target layer includes a fault plane.

[0038] Specifically, refer to Figure 2 1 is a schematic diagram of the structure of the target layer provided by an embodiment of the present invention. The target layer is a stratum of interest in seismic exploration, and the target layer includes a fault plane. The present invention is implemented to accurately determine the range and direction of the fault plane of the target layer according to the target layer.

[0039] Further, Figure 3 The flowchart of determining the formation gradient of the local curved surface model provided by the embodiment of the present invention is as follows. The method of determining the formation gradients corresponding to the multiple local curved surface models according to the seismic data of the target layer also includes the following steps S1001-S1003.

[0040] S1001. Establishing a three-dimensional model of the target layer according to the seismic data of the target layer.

[0041] Further, the establishment of the three-dimensional model of the target layer according to the seismic data of the target layer includes: determining the depth domain layer of the target layer according to the time domain and the longitudinal wave velocity curve of the target layer; and mapping the depth domain layer, line number and channel number of the target layer to a three-dimensional coordinate system to establish the three-dimensional model of the target layer. The seismic data includes the time domain layer, line number and channel number and the longitudinal wave velocity curve.

[0042] Specifically, by collecting seismic data of the target layer, wherein the seismic data includes time domain layers, line numbers, channel numbers, and longitudinal wave velocity curves. In order to facilitate the determination of the stratum in which the target layer is located, the time domain layers of the target layer are converted into depth domain layers of the target layer. Then, the depth domain layers, line numbers, and channel numbers of the target layer are mapped to 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 refer to Figure 2 .

[0043] Further, according to the time domain horizon time and the longitudinal wave velocity curve v of the target layer, determining the depth domain horizon h of the target layer includes:

[0044] Specifically, the one-way propagation time of the wave can be obtained according to the time domain layer time in the seismic data of the target layer: And the velocity of longitudinal wave propagation can be obtained according to the longitudinal wave velocity curve v, and the average velocity of longitudinal wave propagation can be calculated according to the waveform curve. Therefore, the depth domain layer h of the target layer can be calculated according to the above formula.

[0045] S1002. Determine the multiple local surface models according to the three-dimensional model of the target layer.

[0046] Furthermore, determining the multiple local surface models based on the target layer three-dimensional model includes: obtaining multiple center points on the target layer three-dimensional model and multiple face elements corresponding to the multiple center points, wherein each face element includes multiple three-dimensional coordinate points; and determining multiple local surface models based on the multiple three-dimensional coordinate points of each face element in the multiple face elements.

[0047] Specifically, Figure 2 The target layer in is taken as an example. Multiple center points are obtained on the target layer, such as Figure 2 The example of obtaining three center points (A, B, and C) is shown. Of course, any number of center points at any position can also be obtained. The embodiment of the present invention is only for clear explanation of the embodiment of the present invention.

[0048] refer to Figure 4 As shown, A, B, and C are taken as center points, and multiple three-dimensional coordinate points are taken around the center points A, B, and C, such as 3×3 or 5×5 or even more grid points. In order to improve the accuracy of the surface model, the embodiment of the present invention takes 5×5 as an example for explanation (i.e., 25 three-dimensional coordinate points). Among them, the face element of the center point A (B or C) is a grid connected by the 5×5 three-dimensional coordinate points of the center point A (B or C), and the center point is the center point of the 5×5 grid points.

[0049] After obtaining multiple three-dimensional coordinate points, obtain respective facets around the center points A, B, and C, that is, obtain three facets in total, and fit three local surface models (i.e., divide the target layer into three local surfaces) with multiple three-dimensional coordinate points on the three facets. When multiple three-dimensional coordinate points of each facet are known, a quadratic polynomial is used to fit the local surface of each facet, so three local surfaces can be fitted. The specific fitting method can be the following formula, and the coefficients a, b, c, d, e, and f of the polynomial can be obtained by solving the following linear matrix equation system, where the linear coefficients are all constants.

[0050]

[0051] Therefore, for each of the above face elements, 25 three-dimensional coordinate points are obtained. Therefore, n in the above formula corresponds to 25 groups of data. The polynomial coefficients can be solved through the above matrix formula, and then the local surface model of each center point can be fitted. The three surface models after fitting can be referred to Figure 5 .

[0052] S1003. Determine, based on the multiple local curved surface models, multiple formation gradients corresponding to the multiple local curved surface models.

[0053] Furthermore, determining 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, the embodiment of the present invention is still described by taking three surface models as an example. After fitting three local surface models, multiple formation gradients of the center point in each local surface model are determined according to each local surface model. Taking the local surface model corresponding to the center point A as an example, multiple omnidirectional (0-360°) directional derivatives of multiple three-dimensional coordinate points in a two-dimensional plane are respectively calculated, and the existing method for solving directional derivatives can be used to solve them. For example, multiple omnidirectional directional derivatives are calculated for the center point A, such as calculating an azimuth derivative every 1°, and 360 directional derivatives can be obtained.

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

[0056] A total of 360 azimuth derivatives are solved for the local surface model corresponding to the center point A, and the formation gradient of the local surface model corresponding to the center point A is further solved, and the formation gradient with the largest absolute value among the 360 ​​azimuth derivatives is determined as the formation gradient grad of the local surface model corresponding to the center point A. Specifically, the following formula can be used: The direction of the formation gradient grad represents the direction in which the directional derivative of the function at this point is the largest, and its absolute value is equal to the maximum value of the directional derivative.

[0057] The above method can solve the formation gradient of the local surface model corresponding to the center point A. Similarly, the formation gradient of the local surface model corresponding to the center point B or the center point C can also be solved respectively. The method is the same as above and will not be repeated here.

[0058] S101. Obtain cross-sections of local surface models of multiple local surface models according to multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine true curvatures of the cross-sections of the multiple local surface models.

[0059] Furthermore, the method also includes determining the inclination of each local curved surface model by mapping the formation gradients of the multiple local curved surface models onto the two-dimensional coordinates in the three-dimensional coordinate system as the inclination of each local curved surface model.

[0060] Specifically, refer to Figure 6The local surface model corresponding to the center point B is used as an example for explanation. The principle of determining the inclination and strike of the remaining local surface models is the same. Assuming that the formation gradient of the local surface model corresponding to the center point B obtained from the above step S1003 is equal to 2 (that is, the directional derivative is the maximum value equal to 2) and the azimuth is 12° (that is, α = 12°), then the formation gradient (which can be understood as the maximum slope direction of the local surface model corresponding to the center point B) is mapped to the direction of the two-dimensional coordinate system (x, y) of the three-dimensional coordinates and determined as the inclination of the local surface model corresponding to the center point B (such as Figure 6 The s in the figure is the inclination), and the direction perpendicular to the inclination of the local surface model is determined as the direction of the local surface model (such as Figure 6 The t in the equation is the strike direction, which can be used to determine the extension direction of the fault plane).

[0061] refer to Figure 6 The local surface model corresponding to the center point B is still used as an example for explanation. The inclination s corresponding to the local surface model maps the vector s′ on the two-dimensional coordinate plane, and the angle between the vector s′ and the x-axis is According to the direction t of the local surface model, determine the vector ' mapped on the two-dimensional coordinate (x, y) plane in the three-dimensional coordinate system for the direction of each local surface, and the angle between the vector ' and the x-coordinate axis Among them, the angle of the local surface model can be solved by using the existing calculation formula, that is, Among them, atan2 represents the four-quadrant inverse tangent, d and e represent the coefficients of the polynomial of each local surface model, which have been obtained when solving each local surface model in the above step S1002 and are known values.

[0062] According to the above method, we can find is 12°, is 102°. Similarly, the angle between the center point A and the center point C corresponding to the local surface model can be calculated. is 12°, is 102°. For other types of fault planes, such as Figure 7 For the local surface model corresponding to the center point D, the corresponding is -43°, then is 47°.

[0063] Furthermore, obtaining the cross-section lines of the multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-section lines 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 formation gradient of each local surface model, and determining the intersection line with the each local surface model as the cross-section line of each local surface model; and determining the true curvature of the multiple cross-section lines with respect to the inclination according to the cross-section line of each local surface model.

[0064] Specifically, after respectively obtaining the formation gradients of the local surface models of the three center points according to the above method, cutting is performed along the z-axis direction in the three-dimensional coordinate system and in the direction parallel to the formation gradient of each local surface model, and the intersection line with each local surface model is determined as the cross-section line of each local surface model, and reference is made to Figure 6 The solid line PQ in is the cross section of the local surface model at the center point B. Figure 8 The dotted line s1s2 in is the cross-section of the local surface model of the center point A. The method for determining the cross-section of the local surface model corresponding to the center point C is similar and will not be repeated here.

[0065] After respectively finding the cross-sections of the local surface model corresponding to the three center points, further determine the true curvature corresponding to each cross-section (the curvature solved in the prior art is to solve the curvature of the entire surface, while the embodiment of the present invention decomposes the surface into multiple surfaces and respectively finds the curvature of the cross-section of each surface model, so the curvature of each three-dimensional coordinate point on the cross-section can be found, and this curvature is the true curvature). The specific method for solving the cross-section of each local surface model is as follows:

[0066] By rotating the x and y plane coordinates into the coordinate system represented by t and s, the local surface function degenerates into a parabolic function. The specific formula is derived as follows:

[0067] x=scosφ dip ,y=ssinφ dip .

[0068]

[0069]

[0070] Therefore, from the above function, we can see that the local surface function is transformed into a two-variable linear equation, which degenerates into a parabolic function. a, b, c, d, e, and f represent the polynomial coefficients of the cross-section of each local surface model, and the values ​​of these parameters have been calculated in step S1002.

[0071] After finding the function of the cross section of each local surface model, the curvature equation is solved using the existing technology, and the true curvature of the cross section of the local surface model is further solved in combination with the above formula.

[0072] The above method can solve the true curvature of the cross-section of the local surface model of each local surface model. Compared with the prior art that can only solve the curvature of the surface, the embodiment of the present invention converts it into the true curvature of the cross-section of the local surface model of the local surface model. The true curvature of the surface model can be solved in a real sense, laying the foundation for the subsequent accurate determination of the boundary of the fault plane. For details of the specific usage effect, please refer to the following content.

[0073] S102: Determine the direction of each local curved surface model according to the inclination of each local curved surface model.

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

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

[0076] S103, determining a fault plane in the target layer according to a plurality of formation gradients corresponding to the plurality of local curved surface models, the strike direction of each local curved surface model, and the true curvature of the cross-section lines of the plurality of local curved surface models.

[0077] Further, Fig. 9 The method further comprises determining the center line, strike and boundary of the fault plane according to the multiple formation gradients corresponding to the multiple local surface models and the true curvature of the cross-section lines of the multiple local surface models, and the method further comprises the following steps S1020-S1025.

[0078] S1020. Determine the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local surface models as the formation gradient of the fault plane.

[0079] Specifically, the formation gradients of the three local surface models have been solved in the above steps, and the formation gradient of the fault plane will be further determined here. The formation gradients of the three local surface models are compared with each other, for example, the formation gradient of the local surface model of the center point A is 0.89, the formation gradient of the local surface model of the center point B is 2, and the formation gradient of the local surface model of the center point C is 0.97. Therefore, it can be determined that the formation gradient with the largest value among the three local surface models is 2, that is, the local surface model corresponding to the center point B. Take multiple three-dimensional coordinate points along the gradient direction of the center point B respectively, and determine the formation gradient with the largest gradient value among the multiple three-dimensional coordinate points as the formation gradient of the fault plane. Assuming that the three-dimensional coordinate point corresponding to the maximum value of the gradient of the multiple three-dimensional coordinate points along the gradient direction of the center point B is the center point B (it may also be other three-dimensional coordinate points along the center point B), then determine that the center point B is the formation gradient of the fault plane.

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

[0081] Specifically, after determining that the formation gradient of the local curved surface model of the center point B is the formation gradient of the fault plane, the center line of the fault plane is further determined. Figure 5 It can be seen that the formation gradient corresponding to the point along the strike direction of the surface model at the common midline point B is approximately equal to the formation gradient corresponding to the common midline point B, so multiple midpoints of the fault plane can be determined.

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

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

[0084] S1024. Determine the direction of the local curve model corresponding to the formation gradient with the largest value among the multiple formation gradients as the direction of the fault plane.

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

[0086] S1025. Determine, based on the true curvatures of the cross-sections of the multiple local surface models, that the true curvatures of the cross-sections of the local surface models are such that a plurality of three-dimensional coordinate points corresponding to the maximum positive curvature and the minimum negative curvature are the boundaries of the fault plane.

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

[0088] The above method can accurately determine the center line of the fault layer and the two boundaries of the fault layer. Compared with the prior art that can only determine one boundary of the fault layer, the embodiment of the present invention can accurately determine the two boundaries of the fault layer and the center line of the fault layer, thereby improving the accuracy of determining the fault layer. Fig.10 It is the target layer containing multiple fault planes. Fig.11 is the effect diagram of the fault plane solved by the method according to the present invention (i.e. Fig.10 Each fault plane can be accurately interpreted to each point, which is more accurate and detailed than the manual interpretation of fault planes (interpreting faults every ten lines and then interpolating them into fault curves).

[0089] Through the above technical solution, the method uses the seismic data of the target layer to determine multiple formation gradients corresponding to multiple local surface models; obtains the cross-sections of multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-sections of the multiple local surface models; determines the strike of each local surface model according to the inclination of each local surface model; and determines the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models and the strike of each local surface model and the true curvature of the cross-sections of the multiple local surface models. Therefore, the present invention fundamentally solves the technical problem that the prior art cannot accurately determine the curvature of the fault plane and thus cannot accurately determine the fault plane, and improves the accuracy of determining the fault plane.

[0090] Conventional curvature prediction of faults has the problem of position deviation. The maximum curvature and the maximum positive curvature reflect the anticline structure and the boundary of the upper plate of the fault, and the minimum curvature and the minimum negative curvature reflect the syncline structure and the boundary of the foot plate of the fault. Both of them are offset from the core part of the fault, which is not conducive to fault detection. Therefore, the present invention fundamentally solves the technical problem that the prior art cannot accurately determine the curvature of the fault plane and thus cannot accurately determine the fault plane, and improves the accuracy of determining the fault plane.

[0091] On the other hand, an embodiment of the present invention also provides a system for determining a fault plane, the system comprising: a first determination module, used to determine multiple formation gradients corresponding to multiple local surface models based on seismic data of a target layer, wherein the target layer includes a fault plane; a second determination module, used to obtain cross-sections of multiple local surface models based on the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-sections of the multiple local surface models; a third determination module, used to determine the strike of each local surface model based on the inclination of each local surface model; and a fourth determination module, used to determine the fault plane in the target layer based on the multiple formation 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 may be the same determining module or different determining modules. For details of the above-mentioned determination of the fault plane and its effect, please refer to the relevant description of the above-mentioned method for determining the fault plane, which will not be repeated here.

[0093] Furthermore, the second determination module is also used to determine the inclination of each local surface model in the following manner: the direction of the stratigraphic gradients of the multiple local surface models mapped on the two-dimensional coordinates in the three-dimensional coordinate system is determined as the inclination of each local surface model.

[0094] The details of determining the inclination of each local surface model and its effect can be found in the related description of the method for determining the fault plane, which will not be elaborated here.

[0095] Furthermore, the third determination module is used to determine the direction of each local surface model according to the inclination of each local surface model, including: determining the direction on each local surface model that is perpendicular to the inclination of each local surface model as the direction of each local surface model.

[0096] For details on the above determination of the direction of each local surface model and its effect, please refer to the relevant description of the above method for determining the fault plane, which will not be repeated here.

[0097] Furthermore, the second determination module is used to obtain the cross-sections of multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model, so as to determine the true curvature of the cross-sections of the multiple local surface models, including: cutting along the z-coordinate axis direction in the three-dimensional coordinate system and in the direction parallel to the formation 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 inclination according to the cross-section of each local surface model. The fourth determination module is used to determine the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local curved surface models, the strike of each local curved surface model, and the true curvature of the cross-section of the multiple local curved surface models, including: determining the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local curved surface models, the strike of each local curved surface model, and the true curvature of the cross-section of the multiple local curved surface models, including: determining the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local curved surface models as the formation gradient of the fault plane; degree; determining a plurality of three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane as a plurality of midpoints of the fault plane; determining a connecting line of the plurality of midpoints of the fault plane along the direction of the local curved surface model as the centerline of the fault plane; determining the direction of the local curved model corresponding to the stratigraphic gradient with the largest value among the plurality of stratigraphic gradients as the direction of the fault plane; and determining, based on the true curvatures of the cross-sections of the plurality of local curved surface models, a plurality of three-dimensional coordinate points corresponding to the true curvatures of the cross-sections of the local curved surface models with the maximum positive curvature and the minimum negative curvature as the boundaries of the fault plane.

[0098] Regarding the above-mentioned determination of the direction, centerline and boundary details of the fault plane and their effects, please refer to the relevant description of the above-mentioned method for determining the fault plane, which will not be repeated here. It should be understood by those skilled in the art that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0099] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0100] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions 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] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0104] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0105] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0106] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A method for determining a fault plane using formation gradient and dip curvature, characterized in that: The method comprises: Determine multiple formation gradients corresponding to multiple local surface models according to seismic data of a target layer, wherein the target layer includes a fault plane; According to the multiple formation gradients corresponding to the multiple local curved surface models and the inclination of each local curved surface model, cross-section lines of the multiple local curved surface models are obtained to determine the true curvature of the cross-section lines of the multiple local curved surface models; Determining the direction of each local curved surface model according to the inclination of each local curved surface model; and The fault plane in the target layer is determined according to the multiple formation gradients corresponding to the multiple local curved surface models, the strike direction of each local curved surface model, and the true curvature of the cross-section lines of the multiple local curved surface models.

2. The method according to claim 1, characterized in that Determining multiple formation gradients corresponding to multiple local surface models according to the seismic data of the target layer includes: said establishing a three-dimensional model of the target layer according to the seismic data of the target layer; Determining the plurality of local surface models according to the target layer three-dimensional model; and According to the multiple local curved surface models, multiple formation gradients corresponding to the multiple local curved surface models are determined.

3. The method according to claim 2, characterized in that The seismic data include time domain horizon, line number and trace number, and P-wave velocity curve. The establishing of the three-dimensional model of the target layer according to the seismic data of the target layer comprises: Determining the depth domain layer of the target layer according to the time domain layer of the target layer and the P-wave velocity curve; and The depth domain layer, line number and track number of the target layer are mapped to 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 Determining the depth domain layer h of the target layer according to the time domain layer time and the P-wave velocity curve v comprises:

5. The method according to claim 2, characterized in that: Determining the plurality of local surface models according to the target layer three-dimensional model comprises: Acquire a plurality of center points on the three-dimensional model of the target layer and a plurality of facets corresponding to the plurality of center points, wherein each facet includes a plurality of three-dimensional coordinate points; and The multiple local surface models are determined according to the multiple three-dimensional coordinate points of each of the multiple surface elements.

6. The method according to claim 5, characterized in that Determining, according to the multiple local curved surface models, multiple formation gradients corresponding to the multiple local curved surface models comprises: According to each local surface model, determining a plurality of omnidirectional directional derivatives of a central point in each local surface model; and The directional derivative with the largest absolute value among the multiple omnidirectional directional derivatives of the central 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 comprises: determining the tendency of each local curve model by: The directions in which the formation gradients of the plurality of local curved surface models are mapped onto the two-dimensional coordinates in the three-dimensional coordinate system are determined as the inclination of each local curved surface model.

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

9. The method according to claim 1, characterized in that: The step of acquiring the cross-section lines of the multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-section lines of the multiple local surface models comprises: Cutting along the z-axis direction in the three-dimensional coordinate system and in a direction parallel to the formation gradient of each local curved surface model, and determining the intersection line with each local curved surface model as the cross-section line of each local curved surface model; and According to the cross-section lines of each local surface model, the true curvature of the multiple cross-section lines with respect to the inclination is determined.

10. The method according to claim 9, characterized in that Determining the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local curved surface models, the strike of each local curved surface model, and the true curvature of the cross-section lines of the multiple local curved surface models comprises: Determine the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local curved surface models as the formation gradient of the fault plane; Determining a plurality of three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane as a plurality of midpoints of the fault plane; Determine a connecting line of multiple midpoints of the fault plane along the direction of the local curved surface model as the midline of the fault plane; Determine the direction of the local curve model corresponding to the formation gradient with the largest value among the multiple formation gradients as the direction of the fault plane; and According to the true curvatures of the cross-sections of the multiple local surface models, multiple three-dimensional coordinate points corresponding to the maximum positive curvature and the minimum negative curvature of the cross-sections of the local surface models are determined as boundaries of the fault plane.

11. A system for determining fault planes using formation gradient and dip curvature, characterized in that: The system comprises: A first determination module is used to determine a plurality of formation gradients corresponding to a plurality of local surface models according to seismic data of a target layer, wherein the target layer includes a fault plane; A second determination module is used to obtain cross-sections of multiple local curved surface models according to multiple formation gradients corresponding to the multiple local curved surface models and the inclination of each local curved surface model, so as to determine true curvatures of the cross-sections of the multiple local curved surface models; A third determining module, configured to determine the direction of each local curved surface model according to the inclination of each local curved surface model; and The fourth determination module is used to determine the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local surface models, the trend 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 determination module is further configured to determine the tendency of each local surface model in the following manner: The directions in which the formation gradients of the plurality of local curved surface models are mapped onto the two-dimensional coordinates in the three-dimensional coordinate system are determined as the inclination of each local curved surface model.

13. The system according to claim 12, characterized in that The third determining module, for determining the direction of each local curved surface model according to the tendency of each local curved surface model, comprises: The direction on each local curved surface model that is perpendicular to the inclination of each local curved surface model is determined as the direction of each local curved surface model.

14. The system according to claim 11, characterized in that The second determination module is used to obtain the cross-section lines of the multiple local surface models according to the multiple formation gradients corresponding to the multiple local surface models and the inclination of each local surface model to determine the true curvature of the cross-section lines of the multiple local surface models, including: Cutting along the z-axis direction in the three-dimensional coordinate system and in a direction parallel to the formation gradient of each local curved surface model, and determining the intersection line with each local curved surface model as the cross-section line of each local curved surface model; and According to the cross-section lines of each local surface model, the true curvature of the multiple cross-section lines with respect to the inclination is determined.

15. The system according to claim 11, characterized in that The fourth determination module is used to determine the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local curved surface models and the strike of each local curved surface model and the true curvature of the cross-section line of the multiple local curved surface models, including: Determining the fault plane in the target layer according to the multiple formation gradients corresponding to the multiple local curved surface models, the strike of each local curved surface model, and the true curvature of the cross-section lines of the multiple local curved surface models comprises: Determine the formation gradient with the largest value among the multiple formation gradients corresponding to the multiple local curved surface models as the formation gradient of the fault plane; Determining a plurality of three-dimensional coordinate points corresponding to the stratigraphic gradient of the fault plane as a plurality of midpoints of the fault plane; Determine a connecting line of multiple midpoints of the fault plane along the direction of the local curved surface model as the midline of the fault plane; Determine the direction of the local curve model corresponding to the formation gradient with the largest value among the multiple formation gradients as the direction of the fault plane; and According to the true curvatures of the cross-sections of the multiple local surface models, multiple three-dimensional coordinate points corresponding to the maximum positive curvature and the minimum negative curvature of the cross-sections of the local surface models are determined as boundaries of the fault plane.

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