Steeply inclined stratum three-dimensional geological modeling method

Abstract

The invention belongs to the technical field of large-scale three-dimensional geologic model construction and spatial visualization analysis in an underground engineering construction scene, and particularly relates to a steeply-inclined stratum three-dimensional geologic modeling method which comprises the following steps: step 1, establishing a steeply-inclined stratum model conforming to trend and inclination angle constraints; 2, solving an intersection line of an unconformity surface and a steeply-inclined stratum, and completing three-dimensional geological construction of the steeply-inclined stratum and an unconformity contact surface, the step 1 comprises the following steps: 101, arranging a plane geological map and stratum description data of a modeling target area, and extracting a strike line vector graph of the steeply-inclined stratum of the modeling target area; step 102, sampling the strike line at equal intervals according to the strike line vector graph, and extracting a plane coordinate set {Pn} = {Xs, Ys} of the strike line; according to the method, the type and the data volume of the modeling original data can be remarkably reduced, the modeling steps are greatly reduced, the modeling process is shortened, and the modeling efficiency is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of large-scale three-dimensional geological model construction and spatial visualization analysis in underground engineering construction scenes, and specifically relates to a three-dimensional geological modeling method for steeply inclined strata. Background Art

[0002] Three-dimensional geological modeling is a work with strong data dependence. A good three-dimensional geological model needs to be supported by a large amount of basic data. There are usually two ways to model stratigraphic structures in existing three-dimensional geological modeling software. One is to use drilling data for modeling. This method requires extracting stratigraphic layering control points from drilling data, and implicitly modeling the stratigraphic layer with the help of interpolation algorithms to obtain three-dimensional stratigraphic layers. When drilling data is abundant, this method can achieve good modeling results, but when drilling data in the target area is sparse, it is not enough to constrain the interpolation algorithm, and the stratigraphic modeling accuracy is poor. Another method uses three-dimensional seismic data for modeling. Modeling is based on the layer data obtained by three-dimensional seismic interpretation, and the spatial point cloud data of the stratigraphic and fault layers is used to control the generation of three-dimensional models of stratigraphic and fault layers. This method combines well logging interpretation with three-dimensional seismic data to obtain a more accurate three-dimensional geological model. When the target stratum is deeply buried and the drilling cost is too high, this method can achieve better cost control and good modeling results, so it is widely used in three-dimensional geological modeling of oil reservoirs.

[0003] Due to the influence of fold tectonic action, sedimentary strata undergo long-term geodynamic transformation, and the strata dip angles on both sides of the folds change. If the fold compression effect is strong, the strata dip angle changes greatly. If the work area for geological modeling is on one side of a syncline or anticline, the target strata will be monocline strata with a large dip angle. When the strata dip angle is greater than 45°, it is called a steeply inclined strata.

[0004] Steeply inclined strata are common, which have adverse effects on underground engineering construction such as subway tunnel shield and mineral resource mining. It is difficult to accurately obtain a model that conforms to reality when using conventional 3D geological modeling software to model such steeply inclined strata. The above two methods mainly show the following limitations when modeling steeply inclined strata:

[0005] 1) Different interpolation methods have specific requirements for the data used in modeling. When modeling strata based on borehole data, the distribution of strata is controlled by the characteristics of the stratum stratification data in the borehole. If the amount of borehole and stratification data is scarce, the accuracy of interpolation is difficult to guarantee due to the limitation of the algorithm;

[0006] 2) When interpolation methods are used in limited data points, such as minimum curvature, DSI and other methods, their smoothing effect will seriously affect the model accuracy of the interpolation area, the steeply inclined characteristics of the strata cannot be reflected, and layer distortion, holes, intersections and other phenomena will occur.

[0007] 3) When modeling steeply inclined strata and unconformity contact relationships, the existing methods have high intersection line algorithms, which are not conducive to implementation. For example, a method for calculating the intersection line of a free-form surface proposed in Chinese patent CN202210319642.2 uses the Newton-Raphson iteration method to obtain the intersection line of two free-form surfaces. However, since this method requires solving the first-order and second-order partial derivatives and the Hessian matrix, the algorithm complexity is high, which is not conducive to program implementation;

[0008] Therefore, there is an urgent need for a method that is suitable for the lack of 3D seismic interpretation data, can solve the problem of sparse drilling data, and can better realize steeply inclined strata modeling, so as to solve the large-scale 3D geological modeling problem in engineering application scenarios. Summary of the invention

[0009] The purpose of the present invention is to provide a three-dimensional geological modeling method for steeply inclined strata, which can significantly reduce the types and amount of original modeling data, greatly reduce the modeling steps, shorten the modeling process, and effectively improve the modeling efficiency.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A three-dimensional geological modeling method for steeply inclined strata comprises the following steps:

[0012] Step 1: Establish a steeply dipping stratigraphic model that meets the constraints of strike and dip;

[0013] The step 1 comprises the following steps:

[0014] Step 101: extracting a strike line vector graphic of a steeply inclined stratum in a target modeling area;

[0015] Step 102: according to the trend line vector graphics, the trend lines are sampled at equal intervals, and a plane coordinate set {Pn}={Xs, Ys} of the trend lines is extracted as a basic data set for three-dimensional surface interpolation of the stratum;

[0016] Step 104: extracting layered data points of the target strata for modeling from the target area borehole histogram to establish a borehole expansion data set;

[0017] Step 105: Establishing a three-dimensional stratum surface using a centerline method;

[0018] Step 106: Using the inclination and dip constraints, establish a three-dimensional layer line array of the stratum;

[0019] Step 107: using the Delaunay triangulation algorithm to triangulate the curved line array to form a triangulated network;

[0020] Step 108: Based on the vertex data set of the triangulated network and combined with the borehole expansion data set extracted in step 104, a steeply inclined stratum surface control point data set is formed;

[0021] Step 2: Solve the intersection line between the unconformity surface and the steeply inclined stratum surface, and complete the three-dimensional geological construction of the steeply inclined stratum and the unconformity contact surface;

[0022] The step 2 comprises the following steps:

[0023] Step 201: The surfaces to be calculated are set as master and slave surfaces, where the master surface is the clipping surface and the slave surface is the surface to be cut and clipped, and the coordinate intersection operation is performed to obtain [X AC , Y AC , Z AC ];

[0024] Step 202: For the coordinate set [X AC , Y AC , Z AC ] to perform uniform mesh generation, and the mesh spacing is set to (ΔX AC , ΔY AC , ΔZ AC ), the grid spacing in the three-axis directions is the same, and the number of grid units in the three coordinate axis directions of X, Y, and Z are recorded as (m, n, p) respectively;

[0025] Step 203: Set the error threshold to If the calculation is less than the error threshold, the grid cells are considered to be overlapped;

[0026] Step 204: Grid cells Coordinates Substitute f A (X, Y, Z) and f C (X, Y, Z), if and Then the grid unit is on the intersection of surfaces A and C and is marked;

[0027] Step 205: traverse all grid cells and complete the grid cell marking of the surface intersection line;

[0028] Step 206: Use The triangle intersection algorithm finds the intersection point and adds the intersection point to the triangulated network of the two intersecting stratum models. If the intersection point is inside the triangle, a new coordinate point is added inside; if the intersection point is on the edge of the triangle, a new point is added at the point to split the edge.

[0029] Step 207: Connect the vertices of the triangulated network to construct new triangles, and use Delaunay triangulation to perform local reconstruction of the master and slave surfaces;

[0030] Step 208: According to the stratigraphic sequence and sedimentary relationship, the curved surface sub-areas are marked and deleted to complete the three-dimensional geological modeling of the steeply inclined strata and the unconformity contact surface.

[0031] Furthermore, the trend line vector graphics in step 101 are extracted based on the plan geological map and stratigraphic description data of the modeling target area.

[0032] Furthermore, the steps between step 101: and step 104 also include:

[0033] Step 103: Apply curvature constraints to the trend data.

[0034] Furthermore, the step 103 includes the following steps:

[0035] The B-spline curve equation passing through the trend sampling points is obtained by data fitting, set as y = f(x), and one end of the trend line is used as the starting point A. Every three adjacent points are used to calculate the curvature, and traverse to the other end point B of the curve. The curvature at the point Pi (x0, y0) is set to:

[0036]

[0037] The curvature set of the strike curve {k1, k2, ..., k n-2}.

[0038] Furthermore, the borehole expansion data set in step 104 includes the borehole name, borehole coordinates, stratum name, stratum depth or altitude.

[0039] Furthermore, the step 105 includes the following steps:

[0040] Step 105a: Based on the modeled depth range {Z top , Z bottom}Calculate the center line

[0041] Step 105b: Combine the strike line plane coordinate set in step 102, add the Z coordinate to the strike line coordinate set, and establish a three-dimensional coordinate set [X s , Y s , Z center ].

[0042] Furthermore, the step 108 includes the following steps:

[0043] For each vertex on the grid, take a neighborhood B around the point, which satisfies all points whose distance to the point is less than or equal to the given distance d, and define the following matrix:

[0044]

[0045] Where |B| is the area of ​​B; e is the edge of the grid in B; is the unit vector in the direction of e; ||e∩B|| is the length of e∩B, between 0 and |e|; β(e) is the angle between two normal triangles with e as the common side;

[0046] Investigate the eigenvalues ​​and eigendirections of the above matrix. The minimum eigenvalue and eigendirection of the vertex p i The estimated formula of the normal vector of the mesh surface at , the minimum eigenvalue and the maximum eigenvalue are used as the estimated formula of the principal curvatures k1 and k2, so the mean curvature and Gaussian curvature are directly obtained from the principal curvature according to the theory of differential geometry:

[0047]

[0048] The average curvature is used to smooth the surface and generate a three-dimensional stratigraphic surface that conforms to the laws of stratigraphic strike and dip and satisfies the stratigraphic stratification positions revealed by the drilling.

[0049] Furthermore, the step 201 includes the following steps:

[0050] Let the triangulated vertex set of the main surface be f A (X, Y, Z), the coordinate range is [X A , Y A , Z A ], from the triangulated vertex set of the surface is f C (X, Y, Z), the coordinate range is [X C , Y C , Z C ], by calculating the coordinate intersection, we can get the intersection line L of surfaces A and C. AC The total coordinate set [X AC , Y AC , Z AC ].

[0051] The technical effects achieved by the present invention are:

[0052] (1) The present invention uses the strike line of the stratum as the basic data for surface interpolation to achieve the purpose of expanding the interpolation sample set, uses the inclination angle as the normal constraint for three-dimensional surface interpolation, and combines the drilling data to expand the layer control point set to improve local accuracy. The strike and inclination constraints are used to perform three-dimensional interpolation of the stratum layer, which better solves the problem of sparse or even missing drilling and stratum layer data, can better solve the problem of sparse modeling data, and effectively improve the interpolation effect of sparse drilling data.

[0053] (2) The present invention implements a solution algorithm for the intersection line of the formation surface based on a gridding method, without the need for partial derivatives and matrix operations. The algorithm complexity is extremely low, has natural discrete characteristics, and is easy to implement through programming.

[0054] (3) The present invention introduces the collision detection concept in computer-aided design, establishes bounding boxes for possible intersecting stratum models, constructs an octree to screen the bounding boxes where potential intersecting triangles are located, and then divides the space occupied by the bounding boxes into small cubes, establishes a triangle space index, and if the same cube contains triangles from two models, the intersection line of the two triangles is obtained. This method simplifies the solution of intersection lines of different surfaces to the intersection of intersecting triangles, can quickly exclude triangles that do not intersect, improves computing efficiency, is suitable for the reconstruction of contact relationships of steeply inclined stratum models, and can meet the needs of fault-cut sedimentary stratum modeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a schematic diagram of a steeply inclined stratum of the present invention;

[0056] Figure 2 It is a schematic diagram of a set of sampling points of a trend line of the present invention;

[0057] Figure 3 It is a schematic diagram of calculating the curvature of the curve of the present invention;

[0058] Figure 4 It is a schematic diagram of the layer line array constrained by the strike, dip and dip angle of the present invention;

[0059] Figure 5 It is a schematic diagram of the triangulation of the ground plane of the present invention;

[0060] Figure 6 It is a schematic diagram of the intersection of curved surfaces of the present invention;

[0061] Figure 7 It is the discretization calculation surface intersection diagram of the present invention;

[0062] Figure 8 It is a local reconstruction diagram of the triangulated network of the present invention;

[0063] Fig. 9 This is a graph showing the surface intersection line extraction results of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0065] like Figure 1-9As shown, a method for three-dimensional geological modeling of steeply inclined strata comprises the following steps:

[0066] Step 1: Establish a steeply dipping stratigraphic model that meets the constraints of strike and dip;

[0067] Schematic diagram of steeply inclined strata Figure 1 , step 1 proposed by the present invention comprises the following steps:

[0068] Step 101: Arrange the plan geological map and stratigraphic description data of the target area for modeling, and extract the strike line vector graphics of the steeply inclined stratigraphic areas in the target area for modeling;

[0069] The plane geometry of the steeply inclined stratum strike line in step 101 can be obtained with the aid of GIS or CAD software;

[0070] Step 102: According to the trend line vector graphics, the trend line is first sampled at equal intervals to extract the plane coordinate set {Pn} = {Xs, Ys} of the trend line as the basic data set for the three-dimensional surface interpolation of the formation. The extracted trend line sampling points are as follows: Figure 2 As shown;

[0071] Here, the plane coordinate sampling interval can be determined by the modeling accuracy and the size of the modeling target area. A small sampling interval will increase the amount of subsequent calculations.

[0072] Step 103: Apply curvature constraints to the trend data. This step is optional and can be performed based on user needs. It can be used for thinning trend data points and layer smoothing control.

[0073] Specifically, step 103 includes the following steps:

[0074] The B-spline curve equation passing through the trend sampling points can be quickly obtained by data fitting, set as y = f (x), and take one end of the trend line as the starting point A (such as Figure 2 A in the figure), every three adjacent points are used to calculate the curvature, and the curve is traversed to the other end point B. Figure 3 The curvature at the point Pi(x0,y0) shown is:

[0075]

[0076] By calculating formula (1), we can get the curvature set of the strike curve {k1, k2, ..., k n-2}.

[0077] By setting the r value in equation (1), the curvature can be appropriately thresholded to avoid a sharp change in the strike of the created stratigraphic layer. At the same time, the data points are thinned out in areas with small strike changes to reduce the amount of calculation in subsequent steps.

[0078] Step 104: extracting the hierarchical data points of the target formation to be modeled from the target area borehole histogram, and establishing a borehole expansion data set, the formed data set must include the borehole name, borehole mouth coordinates, formation name, and layer depth or altitude, as shown in Table 1;

[0079] Table 1 Example of drilling layer data table

[0080]

[0081] Step 105: Establishing a three-dimensional stratum surface using a centerline method;

[0082] Step 105 includes the following steps:

[0083] Step 105a: Based on the modeled depth range {Z top , Z bottom}Calculate the center line

[0084] Step 105b: Combine the strike line plane coordinate set in step 102, add the Z coordinate to the strike line coordinate set, and establish a three-dimensional coordinate set [X s , Y s , Z center ];

[0085] Step 106: Using the inclination and dip constraints, establish a three-dimensional layer line array of the stratum;

[0086] Step 106 includes the following steps:

[0087] Step 106a: By moving toward the center line three-dimensional coordinate point (x i ,y i , z center ) is to be drawn perpendicular to the tangent of the strike line at that point and whose angle with the horizontal plane is the dip of the stratum;

[0088] Step 106b: Obtain the direction vector of the straight line in step 106a according to the definition of the inclination and the inclination angle α Thus, the linear equation of the inclination line is obtained, which constitutes the line array of the stratum layer, that is, the three-dimensional stratum layer line array, as shown in the following figure: Figure 4 As shown;

[0089] Step 107: Use the Delaunay triangulation algorithm to triangulate the surface line array to form a triangulated network, as follows: Figure 5 As shown;

[0090] Step 108: Based on the vertex data set of the triangulated network and combined with the borehole expansion data set extracted in step 104, a steeply inclined stratum surface control point data set is formed;

[0091] Due to the addition of the borehole expansion data set, the surface control points may deviate from or conflict with each other, so the surface is smoothed by using a mesh curvature algorithm, wherein step 108 includes the following steps:

[0092] For each vertex on the grid, take a neighborhood B around the point, which is selected to satisfy all points whose distance to the point is less than or equal to the given distance d. For simplicity, we can directly take all the points in the sphere with the point as the center and the radius d. In the following, we only consider the points and edges in the sphere, and define the following matrix:

[0093]

[0094] Where |B| is the area of ​​B; e is the edge of the grid in B; is the unit vector in the direction of e; ||e∩B|| is the length of e∩B||, which is between 0 and |e|; β(e) is the angle between the two normal triangles with e as the common side.

[0095] Investigate the eigenvalues ​​and eigendirections of the above matrix. The minimum eigenvalue and characteristic direction of the vertex p i The estimated formula of the normal vector of the mesh surface at , the minimum eigenvalue and the maximum eigenvalue can be used as the estimated formula of the principal curvatures k1 and k2, so the mean curvature and Gaussian curvature can be directly obtained from the principal curvature according to the theory of differential geometry:

[0096]

[0097] Therefore, the average curvature is used to smooth the surface, generating a three-dimensional stratigraphic surface that conforms to the laws of stratigraphic strike and dip angle and satisfies the stratigraphic stratification position revealed by the borehole.

[0098] The above steps are also applicable to three-dimensional modeling of large-angle fault planes.

[0099] Step 2: Solve the intersection line between the unconformity surface and the steeply inclined stratum surface, and complete the three-dimensional geological construction of the steeply inclined stratum and the unconformity contact surface;

[0100] Step 2 includes the following steps:

[0101] Step 201: Set the surfaces to be calculated as master and slave surfaces, respectively, where the master surface is the clipping surface and the slave surface is the surface to be cut and clipped, such as Figure 6 The unconformity surface shown in is the main surface.

[0102] Specifically, step 201 includes the following steps:

[0103] Let the triangulated vertex set of the main surface be f A (X, Y, Z), the coordinate range is [XA , Y A , Z A ], from the triangulated vertex set of the surface is f C (X, Y, Z), the coordinate range is [X C , Y C , Z C ], by calculating the coordinate intersection, we can get the intersection line L of surfaces A and C. AC The total coordinate set [X AC , Y AC , Z AC ];

[0104] Step 202: For the coordinate set [X AC , Y AC , Z AC ] to perform uniform mesh generation, and the mesh spacing is set to (ΔX AC , ΔY AC , ΔZ AC ), for the sake of simplicity, the grid spacing in the three-axis direction can be made the same, and the number of grid units in the three coordinate axis directions of X, Y, and Z are recorded as (m, n, p) respectively;

[0105] Step 203: Set the error threshold to If the calculation is less than the error threshold, the grid cells are considered to be overlapped;

[0106] Step 204: Grid cells Coordinates Substitute f A (X, Y, Z) and f C (X, Y, Z), if and Then the grid unit is on the intersection of surfaces A and C and is marked;

[0107] Step 205: Traverse all grid cells and complete the grid cell marking of the surface intersection line, such as Figure 7 As shown;

[0108] Step 206: Use The triangle intersection algorithm finds the intersection point and adds the intersection point to the triangulated network of the two intersecting stratum models. If the intersection point is inside the triangle, a new coordinate point is added inside; if the intersection point is on the edge of the triangle, a new point is added at the point to split the edge. Figure 8 As shown;

[0109] Step 207: Connect the vertices of the triangulated network to construct new triangles, and use Delaunay triangulation to perform local reconstruction of the master and slave surfaces, such as Fig. 9 As shown;

[0110] Step 208: Mark and delete the curved surface sub-areas according to the stratigraphic sequence and sedimentary relationship, thereby completing the three-dimensional geological modeling of the steeply inclined strata and unconformity contact surface.

[0111] In summary, the present invention proposes a convenient method for constructing a structural model for steeply inclined sedimentary strata, which can significantly reduce the type and amount of original modeling data compared to traditional three-dimensional geological modeling software, greatly reduce modeling steps, shorten the modeling process, and effectively improve modeling efficiency. The present invention has the following technical features:

[0112] The present invention uses strike and dip constraints to perform three-dimensional interpolation of the stratigraphic layer, which effectively solves the problem of sparse or even missing drilling and stratigraphic layering data. The present invention uses the strike line of the stratigraphic layer as the basic data for surface interpolation to achieve the purpose of expanding the interpolation sample set. At the same time, the dip is used as the normal constraint for three-dimensional surface interpolation, and the drilling data is combined to expand the layer control point set to improve local accuracy. It can better solve the problem of sparse modeling data and effectively improve the interpolation effect of sparse drilling data.

[0113] The present invention proposes a method for calculating the intersection line of unconformity surfaces suitable for steeply inclined strata. The solution algorithm for the intersection line of strata surfaces is implemented based on a gridding method. No partial derivative and matrix operations are required. The algorithm has extremely low complexity, has natural discrete characteristics, and is easy to implement through programming.

[0114] The present invention introduces the collision detection concept in computer-aided design, establishes bounding boxes for possible intersecting stratum models, constructs an octree to screen out bounding boxes where potential intersecting triangles are located, and then divides the space occupied by the bounding boxes into small cubes, establishes a triangle space index, and if the same cube contains triangles from two models, the intersection line of the two triangles is obtained. This method simplifies the solution of intersection lines of different surfaces to the intersection of intersecting triangles, can quickly exclude triangles that do not intersect, improves computing efficiency, is suitable for the reconstruction of contact relationships of steeply inclined stratum models, and can meet the needs of fault-cut sedimentary stratum modeling.

[0115] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. A three-dimensional geological modeling method for steeply inclined strata, characterized by: The following steps are involved: Step 1: Establish a steeply dipping stratigraphic model that meets the constraints of strike and dip; The step 1 comprises the following steps: Step 101: extracting a strike line vector graphic of a steeply inclined stratum in a target modeling area; Step 102: According to the trend line vector graphics, the trend lines are sampled at equal intervals to extract the plane coordinate set of the trend lines {P n }={X s , Y s }, as the basic data set for 3D surface interpolation of strata; Step 104: extracting layered data points of the target strata for modeling from the target area borehole histogram to establish a borehole expansion data set; Step 105: Establishing a three-dimensional stratum surface using a centerline method; Step 106: Using the inclination and dip constraints, establish a three-dimensional layer line array of the stratum; Step 107: using the Delaunay triangulation algorithm to triangulate the curved line array to form a triangulated network; Step 108: Based on the vertex data set of the triangulated network and combined with the borehole expansion data set extracted in step 104, a steeply inclined stratum surface control point data set is formed; Step 2: Solve the intersection line between the unconformity surface and the steeply inclined stratum surface, and complete the three-dimensional geological construction of the steeply inclined stratum and the unconformity contact surface; The step 2 comprises the following steps: Step 201: Set the surfaces to be calculated as master and slave surfaces, where the master surface is the clipping surface and the slave surface is the surface to be cut and clipped, and calculate the coordinate set [X AC , Y AC , Z AC ]; Step 202: For the coordinate set [X AC , Y AC , Z AC ] to perform uniform mesh generation, and the grid spacing is set to (ΔX AC , Y AC , ΔZ AC ), the grid spacing in the three-axis directions is the same, and the number of grid units in the X, Y, and Z coordinate axis directions are recorded as (m, n, p) respectively; Step 203: Set the error threshold to If the calculation is less than the error threshold, the grid cells are considered to be overlapped; Step 204: Grid cells Coordinates Substitute f A (X, Y, Z) and f C (X, Y, Z), if and Then the grid unit is on the intersection of surfaces A and C and is marked; Step 205: traverse all grid cells and complete the grid cell marking of the surface intersection line; Step 206: Use The triangle intersection algorithm finds the intersection point and adds the intersection point to the triangulated network of the two intersecting stratum models. If the intersection point is inside the triangle, a new coordinate point is added inside; if the intersection point is on the edge of the triangle, a new point is added at the point to split the edge. Step 207: Connect the vertices of the triangulated network to construct new triangles, and use Delaunay triangulation to perform local reconstruction of the master and slave surfaces; Step 208: According to the stratigraphic sequence and sedimentary relationship, the curved surface sub-areas are marked and deleted to complete the three-dimensional geological modeling of the steeply inclined strata and the unconformity contact surface.

2. A method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: The trend line vector graphics in step 101 are extracted based on the planar geological map and stratigraphic description data of the modeling target area.

3. A method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: The step 101: and the step 104 also include: Step 103: Apply curvature constraints to the trend data.

4. A method for three-dimensional geological modeling of steeply inclined strata according to claim 3, characterized in that: The step 103 comprises the following steps: The B-spline curve equation passing through the trend sampling points is obtained by data fitting, set as y = f(x), and one end of the trend line is used as the starting point A. Every three adjacent points are used to calculate the curvature, and traverse to the other end point B of the curve. The curvature at the point Pi (x0, y0) is set to: The curvature set of the strike curve {κ1, κ2, ..., κ n-2 }.

5. The method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: The borehole expansion data set in step 104 includes the borehole name, borehole coordinates, stratum name, stratum depth or altitude.

6. A method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: The step 105 comprises the following steps: Step 105a: Based on the modeled depth range {Z top , Z bottom }Calculate the center line Step 105b: Combine the strike line plane coordinate set in step 102, add the Z coordinate to the strike line coordinate set, and establish a three-dimensional coordinate set [X s , Y s , Z center ].

7. A method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: The step 108 comprises the following steps: For each vertex on the grid, take a neighborhood B around the point, which satisfies all points whose distance to the point is less than or equal to the given distance d, and define the following matrix: Where |B| is the area of ​​B; e is the edge of the grid in B; is the unit vector in the direction of e; ||e∩B|| is the length of e∩B, between 0 and |e|; β(e) is the angle between two normal triangles with e as the common side; Investigate the eigenvalues ​​and eigendirections of the above matrix. The minimum eigenvalue and eigendirection of the vertex p i The normal vector of the mesh surface at is estimated, and the minimum and maximum eigenvalues ​​are used as estimates of the principal curvatures κ1 and κ2. Then the mean curvature and Gaussian curvature are directly obtained from the principal curvatures according to the theory of differential geometry: The average curvature is used to smooth the surface and generate a three-dimensional stratigraphic surface that conforms to the laws of stratigraphic strike and dip and satisfies the stratigraphic stratification positions revealed by the drilling.

8. The method for three-dimensional geological modeling of steeply inclined strata according to claim 1, characterized in that: Calculating the coordinate set in step 201 includes the following steps: Let the triangulated vertex set of the main surface be f A (X, Y, Z), the coordinate range is [X A , Y A , Z A ], the triangulated vertex set of the surface is f C (X, Y, Z), the coordinate range is [X C , Y C , Z C ], by calculating the coordinate intersection, we can get the intersection line L of surfaces A and C. AC The total coordinate set [X AC , Y AC , Z AC ].

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