Method for simulating complex fault in three-dimensional geologic model by using space analytic geometry

Abstract

The invention provides a method for simulating a complex fault in a three-dimensional geologic model by utilizing spatial analytic geometry. The method comprises the following steps: acquiring fault occurrence information of a site to be researched; deriving a normal vector of the fault in a three-dimensional space according to the obtained fault occurrence information; determining representative origin position coordinates of each layer in the coordinate system of the to-be-simulated region; establishing a three-dimensional geological model according to the two-dimensional geological profile; and according to the normal vector of the fault in the three-dimensional space and the representative origin position coordinates of each layer in the coordinate system of the to-be-simulated region, performing accurate sorting and division on the target fault in the three-dimensional geologic model, thereby realizing consideration of complex fault information in the three-dimensional geologic model. The method can completely reflect on-site real fault distribution characteristics, and is simple and easy to implement and high in modeling efficiency.

Description

Technical Field

[0001] The invention relates to the field of geotechnical engineering numerical simulation, and in particular to a method for simulating complex faults in a three-dimensional geological model by using spatial analytical geometry. Background Art

[0002] Three-dimensional geological modeling has many application values ​​in many fields such as engineering construction and oil and gas storage. Many engineering sites face complex geological conditions, such as faults and other geological units that are crisscrossed. At present, it is difficult to efficiently and accurately reflect the true occurrence information of these geological units in three-dimensional geological modeling. Traditional geological modeling methods are mainly based on information such as multiple boreholes or multiple geological profiles to accurately reconstruct and express the three-dimensional geological information of a certain area. However, this method will cause duplication of geological survey information and increase the cost of geological survey. For example, for the same fault level, its occurrence is often the same within the same area. Repeated surveys of the same fault will undoubtedly waste costs to a certain extent. Summary of the invention

[0003] In view of this, the present invention takes into account the complex fault attitude information and its spatial distribution position, and proposes a method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry. This method can fully reflect the actual fault distribution characteristics on site, is simple and easy to implement, and has high modeling efficiency.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry comprises the following steps:

[0006] The first step is to obtain the fault occurrence information of the site to be studied, wherein the fault occurrence information includes strike, dip and inclination;

[0007] The second step is to derive the normal vector of the fault in three-dimensional space based on the fault attitude information obtained in the first step;

[0008] The third step is to determine the coordinates of the representative origin of each layer in the coordinate system of the area to be simulated;

[0009] Step 4: Establish a three-dimensional geological model based on the two-dimensional geological profile;

[0010] The fifth step is to accurately sort and divide the target faults in the three-dimensional geological model based on the normal vector of the fault in the three-dimensional space obtained in the second step and the representative origin position coordinates of each layer in the coordinate system of the area to be simulated determined in the third step, so as to consider complex fault information in the three-dimensional geological model.

[0011] Furthermore, the first step specifically includes:

[0012] For the site to be studied, all faults are selected, the fault attitude information of all faults is measured using a geological compass, and a preliminary geological profile of the fault is drawn.

[0013] Furthermore, the second step specifically includes:

[0014] Through the principles of spatial analytic geometry, equations between the strike, dip, inclination and plane normal vector of the fault are established. Through the simultaneous equations, the three components of the plane normal vector in space are solved, and then the normal vector of the fault in three-dimensional space is obtained.

[0015] Furthermore, the equations between the strike, dip, inclination and plane normal vector of the fault are established by the principle of spatial analytic geometry, and the three components of the plane normal vector in space are solved by the set of simultaneous equations to obtain the normal vector of the fault in three-dimensional space, which specifically includes:

[0016] The spatial position information of any layer is expressed by using a general plane equation, that is, the plane equation of the fault layer is as follows:

[0017] a x x+a y y+a z z+D=0 (1)

[0018] in, represents the normal vector of the layer, (x, y, z) is the three-dimensional space coordinate in the X(E)-Y(N)-Z(H) coordinate system, and D is the coefficient to be determined;

[0019] (1) Obtain the strike line equation of the fault plane:

[0020] The equation of the horizontal plane passing through the origin is:

[0021] z=0 (2)

[0022] By combining the horizontal plane equation passing through the origin of the coordinate system with the plane equation of the fault plane, we can obtain the strike line equation of the fault plane:

[0023] a x x+a y y+D=0 (3)

[0024] (2) Obtain the dip azimuth of the fault plane according to the strike line equation of the fault plane:

[0025] The dip equation and the strike equation are perpendicular to each other, and the product of the slopes of the two lines should be -1, so the equation of the dip line is:

[0026] a x x y y+D=0 (4)

[0027] The angle θ between the inclination and the positive direction of the Y axis q is the dip azimuth of the fault plane, that is:

[0028]

[0029] Among them, θ q ' is the inverse tangent value to be solved, ranging from 0° to 90°, θ q is the angle between the dip and the positive direction of the Y axis, that is, the dip azimuth of the fault plane, θ q 'According to α x ,α y The positive and negative values ​​of θ are corrected accordingly to obtain q ;

[0030] (3) Obtain the inclination of the fault plane:

[0031] Fault dip is the angle between the fault plane and the horizontal plane, which can be obtained by combining equations (1) and (2):

[0032]

[0033] (4) Obtain the normal vector of the fault in three-dimensional space based on the dip azimuth and inclination of the fault plane:

[0034] In order to make the normal vector of the fault plane a unit normal vector, we have a x 2 +a y 2 +a z 2 =1;

[0035] According to the above formulas, the simultaneous equations are:

[0036]

[0037] In equation (7), θ q is the dip azimuth of the fault plane, which is perpendicular to the strike azimuth. is the inclination of the fault plane, and the three equations are solved simultaneously (a x ,a y ,a z ), calculate the normal vector of the fault in three-dimensional space Furthermore, the θ q 'According to α x ,α y The positive and negative values ​​of θ are corrected accordingly to obtain q , the specific correction relationship is shown in Table 1:

[0038] Table 1 Dip azimuth θ q Correction

[0039]

[0040]

[0041] Furthermore, the third step specifically includes:

[0042] According to the needs of the research problem, determine the size and dimensions of the area to be simulated; according to the three-dimensional geological modeling principle of "X-axis is consistent with E direction, Y-axis is consistent with N direction, and Z-axis is consistent with elevation H", determine the representative origin position coordinates of each layer in the coordinate system of the area to be simulated. At this time, the geological profiles are all in the y=0 plane.

[0043] Furthermore, the fourth step specifically includes:

[0044] A three-dimensional geological model is established based on the two-dimensional geological profile, and the two-dimensional geological profile is imported into the modeling software to construct a three-dimensional geological model without distinguishing the complex fault strike information.

[0045] Furthermore, the modeling software includes Hypermesh software.

[0046] The present invention has the following beneficial effects:

[0047] (1) It can save costs and avoid repeated surveys of the same fault in the region. For example, the strike of a fault in the 3D geological model region is often consistent and does not change much in the entire geodetic coordinates. It is simple and easy to calibrate the position of the fault in the entire 3D geological model region by the strike of the fault and the coordinates of the typical position points, which helps to reduce the cost waste in geological surveys of the same fault.

[0048] (2) The use of spatial analytical geometry to describe the fault attitude has a detailed and reasonable scientific theoretical basis; the position calibration of the fault in the three-dimensional geological model is a typical spatial analytical geometry problem. The spatial analytical geometry equation and normal vector of the fault plane are inferred by the position information such as the fault attitude. It has a rigorous scientific derivation process and is highly credible.

[0049] (3) The fault attitude information and spatial position characteristics are simulated through programming, which is simple to operate and easy to implement; the preliminary construction of the three-dimensional geological model is realized through the fourth step, but the model is not sorted and divided into units such as faults at this time; then through the fifth step, combined with the fault attitude information and spatial position characteristics, the fault units in the three-dimensional geological model of the fourth step are outlined through programming, which has a simple implementation process and high modeling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Provides information on the occurrence of complex faults in site sections;

[0051] Figure 2 It is a schematic diagram of the three-dimensional geological model without distinguishing faults;

[0052] Figure 3 A schematic diagram of a three-dimensional geological model that takes into account complex fault occurrence information;

[0053] Figure 4 It is a schematic diagram of three-dimensional calculation of fault attitude information and space normal vector according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The embodiment of the present invention provides a method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry, comprising the following steps:

[0056] The first step is to obtain the fault occurrence information of the site to be studied.

[0057] For the site to be studied, all faults are selected, and the fault attitude information (including strike, dip, and inclination) of all faults is accurately measured using a geological compass, and a preliminary geological profile of the fault is drawn.

[0058] In the second step, the normal vector of the fault in three-dimensional space is derived based on the fault attitude information obtained in the first step.

[0059] For any fault plane, there is a unique plane equation corresponding to it. The intersection of this plane and the horizontal plane is the strike line of the fault plane. Using the principle of spatial analytic geometry, the vertical line equation of the strike in the horizontal plane is solved to obtain the angle between the dip equation of the fault plane and the Y axis of the geodetic coordinate system. The quadrant of the dip is determined, and the angle is corrected to obtain the dip of the fault plane. The angle between the plane equation of the fault plane and the horizontal plane is the dip angle of the fault. Its principle is consistent with the basic concepts of the strike, dip, and dip angle of the stratum.

[0060] like Figure 4 As shown in the figure, the spatial position information of any layer is represented by a general plane equation, that is, the plane equation of the fault layer is as follows:

[0061] a x x+a y y+a z z+D=0 (1)

[0062] in, represents the normal vector of the layer. (x, y, z) are the three-dimensional space coordinates in the X(E)-Y(N)-Z(H) coordinate system, and D is the coefficient to be determined.

[0063] (1) Obtain the strike line equation of the fault plane:

[0064] The equation of the horizontal plane passing through the origin is:

[0065] z=0 (2)

[0066] The equation of the horizontal plane passing through the origin of the coordinate system is combined with the plane equation of the fault plane (combining equations (1) and (2)), which is the equation of the intersection line of the two planes, and also the equation of the strike line of the fault plane, and we can get:

[0067] a x x+a y y+D=0 (3)

[0068] (2) Obtain the dip azimuth of the fault plane according to the strike line equation of the fault plane:

[0069] The dip equation and the strike equation are perpendicular to each other, and the product of the slopes of the two lines should be -1, so the equation of the dip line can be obtained as:

[0070] a x x y y+D=0 (4)

[0071] The angle θ between the positive direction of the Y axis and the q is the dip azimuth of the fault plane, that is:

[0072]

[0073] Among them, θ q ' is the inverse tangent value to be solved, ranging from 0° to 90°, θ q It is the angle between the dip and the positive direction of the Y axis, that is, the dip azimuth of the fault plane. q 'According to α x ,α y The positive and negative of θ can be corrected accordingly, and we can get q , the specific correction relationship is shown in Table 1.

[0074] Table 1 Dip azimuth θ q Correction

[0075]

[0076] (3) Obtain the inclination of the fault plane:

[0077] Fault dip It is the angle between the fault plane and the horizontal plane, which can be obtained by combining equations (1) and (2):

[0078]

[0079] (4) Obtain the normal vector of the fault in three-dimensional space based on the dip azimuth and inclination of the fault plane.

[0080] In order to make the normal vector of the fault plane a unit normal vector, we can have a x 2 +a y 2 +a z 2 =1.

[0081] According to the above equations, we can solve the system of equations:

[0082]

[0083] In equation (7), θ q is the dip azimuth of the fault plane, which is perpendicular to the strike azimuth. is the inclination of the fault plane, and these are all factors of the fault plane’s attitude. There are a total of unknown quantities (a x ,a y ,a z ) three, can be solved by the three simultaneous equations. Therefore, combining equation (7) and the correction of the dip azimuth in Table 1, the normal vector of the fault in three-dimensional space can be calculated:

[0084] The third step is to determine the representative origin position coordinates of each layer in the coordinate system of the area to be simulated.

[0085] According to the needs of the research problem, determine the size and dimensions of the area to be simulated; according to the three-dimensional geological modeling principle of "X-axis is consistent with E direction, Y-axis is consistent with N direction, and Z-axis is consistent with elevation (H)", determine the representative origin position coordinates of each layer in the coordinate system of the area to be simulated. Note that the geological profiles are all in the y=0 plane at this time.

[0086] Step 4: Establish a 3D geological model based on the 2D geological profile

[0087] Import the two-dimensional geological profile into professional modeling software such as Hypermesh to construct a three-dimensional geological model without distinguishing the occurrence information of complex faults.

[0088] Step 5: Sorting and division of complex faults

[0089] Based on the normal vector of the fault in the three-dimensional space obtained in the second step and the representative origin position coordinates of each layer in the coordinate system of the area to be simulated obtained in the third step, a program is compiled to accurately sort and divide the target faults in the three-dimensional geological model, that is, it is possible to consider complex fault information in the three-dimensional geological model.

[0090] Embodiment: The engineering geological conditions of a water diversion project site are very complex, with crisscross inclined faults. The present invention is used to carry out a case study demonstration of a method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry.

[0091] Step 1: Obtain information on the occurrence of complex faults at the site

[0092] For the site to be studied, all faults were selected and the true strike information of these faults was accurately measured using a geological compass. The following strike information can be obtained: Fault B22-F2: 211°∠59°(29°); Fault B22-F1: 320°∠68°(62°); Fault B22-f3: 132°∠62°(58°); Fault B22-f10: 196°∠65°(10°); Fault NKB6-F1: 145°∠30°(22°); Fault NKB6-F2: 145°∠30°(30°); Fault NKB5-F1: 277°∠48°(48°). Figure 1 The strike information of all faults in the site section is given.

[0093] Step 2: Derivation of the normal vector of the plane based on the fault attitude information

[0094] By using the principles of spatial analytic geometry and solving the vertical equation of the fault plane strike line in the horizontal plane, we can get the angle between the fault dip equation and the Y axis of the geodetic coordinate system. By determining the quadrant where the dip is located and correcting the angle, we can get the dip of the fault. The angle between the plane equation of the fault plane and the horizontal plane is the dip angle of the fault. The normal vectors of each plane can be obtained as:

[0095] Fault B22-F2: (-0.6061,-0.3642,0.7071); Fault B22-F1: (0.7103,-0.5960,0.3746); Fault B22-f3: (-0.5908,0.6561,0.4695); Fault B22-f10: (-0.8712,-0.2498,0.4226); Fault NKB6-F1: (-0.4096,0.2868,0.8660); Fault NKB6-F2: (-0.4096,0.2868,0.8660); Fault NKB5-F1: (0.0906,-0.7376,0.6691).

[0096] Step 3: Determine the representative origin position coordinates of each layer in the coordinate system of the area to be simulated

[0097] According to the research problem, determine the size and dimensions of the area to be simulated; according to the three-dimensional geological modeling principle of "X axis is consistent with E direction, Y axis is consistent with N direction, Z axis is consistent with elevation (H)", determine the spatial position coordinates of each layer on the geological section. Note that the geological section is the y=0 plane at this time. The representative origin coordinates of each layer can be obtained as:

[0098] Fault B22-F2: (-57.7000, 0.0000, -75.4772) and (-57.7000, 0.0000, -81.3772); Fault B22-F1: (-54.7000, 0.0000, -33.0425) and (-48.6759, 0.0000, -33.3384); Fault B22-f3: (-64.6790, 0.0000, -85.2213) and (-61.0000, 0.0000, -85.2213); Fault B2 2-f10: (0.0000, 0.0000, -128.6573) and (0.0000, 0.0000, -131.3573); fault NKB6-F1: (0.0000, 0.0000, -60.0000) and (101.9061, 0.0000, -55.4949); fault NKB6-F2: (57.3381, 0.0000, -111.4753); fault NKB5-F1: (132.5286, 0.0000, -48.6504).

[0099] Step 4: Establish a 3D geological model based on the geological profile

[0100] Import the 2D geological profile into professional modeling software such as Hypermesh to construct a 3D geological model without distinguishing the fault occurrence information. Figure 2 A schematic diagram of the three-dimensional geological model corresponding to the undifferentiated faults is given.

[0101] Step 5: Fault Sorting and Division

[0102] According to the coordinates of the representative origin positions of each layer and the normal vectors of the layer obtained above, a program is compiled to accurately sort and divide the target faults, so that a three-dimensional geological model considering complex fault information can be obtained, such as Figure 3 .and Figure 2 compared to, Figure 3 The distribution location and size of faults in the three-dimensional geological model can be accurately reflected, and the simulation effect is obvious.

[0103] The present invention calibrates the spatial position of the fault in the three-dimensional geological model of the entire region according to the geological occurrence information of the fault, which is conducive to the simulation of complex faults in the three-dimensional geological model, is simple and easy to operate, and has high modeling efficiency.

[0104] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry, characterized in that: The steps include: The first step is to obtain the fault occurrence information of the site to be studied, wherein the fault occurrence information includes strike, dip and inclination; The second step is to derive the normal vector of the fault in three-dimensional space based on the fault attitude information obtained in the first step; The third step is to determine the coordinates of the representative origin of each layer in the coordinate system of the area to be simulated; Step 4: Establish a three-dimensional geological model based on the two-dimensional geological profile; The fifth step is to accurately sort and divide the target faults in the three-dimensional geological model based on the normal vector of the fault in the three-dimensional space obtained in the second step and the representative origin position coordinates of each layer in the coordinate system of the area to be simulated determined in the third step, so as to consider complex fault information in the three-dimensional geological model.

2. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry according to claim 1, characterized in that: The first step specifically includes: For the site to be studied, all faults are selected, the fault attitude information of all faults is measured using a geological compass, and a preliminary geological profile of the fault is drawn.

3. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry according to claim 1, characterized in that: The second step specifically includes: Through the principles of spatial analytic geometry, equations between the strike, dip, inclination and plane normal vector of the fault are established. Through the simultaneous equations, the three components of the plane normal vector in space are solved, and then the normal vector of the fault in three-dimensional space is obtained.

4. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry as claimed in claim 3, characterized in that: The above method uses the spatial analytic geometry principle to establish equations between the strike, dip, inclination and plane normal vector of the fault, solves the three components of the plane normal vector in space through a set of simultaneous equations, and then obtains the normal vector of the fault in three-dimensional space, specifically including: The spatial position information of any layer is expressed by using a general plane equation, that is, the plane equation of the fault layer is as follows: a x x+a y y+a z z+D=0 (1) in, represents the normal vector of the layer, (x, y, z) is the three-dimensional space coordinate in the X(E)-Y(N)-Z(H) coordinate system, and D is the coefficient to be determined; (1) Obtain the strike line equation of the fault plane: The equation of the horizontal plane passing through the origin is: z＝0 (2) By combining the horizontal plane equation passing through the origin of the coordinate system with the plane equation of the fault plane, we can obtain the strike line equation of the fault plane: a x x+a y y+D=0 (3) (2) Obtain the dip azimuth of the fault plane according to the strike line equation of the fault plane: The dip equation and the strike equation are perpendicular to each other, and the product of the slopes of the two lines should be -1, so the equation of the dip line is: a x x-a y y+D=0 (4) The angle θ between the inclination and the positive direction of the Y axis q is the dip azimuth of the fault plane, that is: Among them, θ q ' is the inverse tangent value to be solved, ranging from 0° to 90°, θ q is the angle between the dip and the positive direction of the Y axis, that is, the dip azimuth of the fault plane, θ q 'According to α x ,α y The positive and negative values ​​of θ are corrected accordingly to obtain q ; (3) Obtain the inclination of the fault plane: Fault dip is the angle between the fault plane and the horizontal plane, which can be obtained by combining equations (1) and (2): (4) Obtain the normal vector of the fault in three-dimensional space based on the dip azimuth and inclination of the fault plane: In order to make the normal vector of the fault plane a unit normal vector, we have a x 2 +a y 2 +a z 2 =1; According to the above formulas, the simultaneous equations are: In equation (7), θ q is the dip azimuth of the fault plane, which is perpendicular to the strike azimuth. is the inclination of the fault plane, and the three equations are solved simultaneously (a x ,a y ,a z ), calculate the normal vector of the fault in three-dimensional space 5. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry as claimed in claim 4, characterized in that: The θ q 'According to α x ,α y The positive and negative values ​​of θ are corrected accordingly to obtain q , the specific correction relationship is shown in Table 1: Table 1 Dip azimuth θ q Correction 6. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry according to claim 1, characterized in that: The third step specifically includes: According to the needs of the research problem, determine the size and dimensions of the area to be simulated; according to the three-dimensional geological modeling principle of "X-axis is consistent with E direction, Y-axis is consistent with N direction, and Z-axis is consistent with elevation H", determine the representative origin position coordinates of each layer in the coordinate system of the area to be simulated. At this time, the geological profiles are all in the y=0 plane.

7. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry according to claim 1, characterized in that: The fourth step specifically includes: A three-dimensional geological model is established based on the two-dimensional geological profile, and the two-dimensional geological profile is imported into the modeling software to construct a three-dimensional geological model without distinguishing the complex fault strike information.

8. The method for simulating complex faults in a three-dimensional geological model using spatial analytical geometry according to claim 7, characterized in that: The modeling software includes Hypermesh software.

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