Complex magnetic body in-well magnetic field three-component calculation method, device, equipment and medium

Abstract

Method, device, equipment and medium for calculating three components of magnetic field in borehole of complex magnetic body, determining a target area, constructing a prism model with the target area included therein; performing grid meshing on the prism model to divide it into a number of small prism units, assigning magnetic susceptibility values to each small prism unit; using a three-dimensional discrete convolution method to calculate each component of the three components of the magnetic field in the borehole generated by each small prism unit at the observation point in the borehole; and obtaining the three components of the magnetic field in the borehole generated by the entire prism model at the observation point in the borehole based on each component of the three components of the magnetic field in the borehole generated by each small prism unit at the observation point in the borehole. The present invention can adapt to the rapid and high-precision calculation of the three components of the magnetic field in the borehole of a magnetic body with arbitrary magnetic susceptibility distribution and complex shape, and realizes the unity of calculation accuracy and calculation efficiency of the three components of the magnetic field in the borehole of a complex magnetic body.

Description

Technical Field

[0001] The present invention belongs to the technical field of numerical simulation of magnetic fields of magnetic bodies, and particularly relates to a method, device, equipment and medium for calculating three components of the magnetic field in a well of a magnetic body with an arbitrary magnetic susceptibility distribution and a complex shape. Background Technique

[0002] Compared with ground and airborne magnetic exploration methods, borehole magnetic exploration can better reflect information such as the position of the field source because it is closer to the field source body. With the development of borehole magnetic observation equipment, borehole magnetic field measurement has gradually become an important exploration method. To meet the requirements of joint inversion of three-component data of ground-borehole magnetic fields, efficient calculation of three components of the borehole magnetic field has become an urgent problem to be solved. Compared with the calculation of three components of ground and airborne magnetic fields, since the observation points in the borehole are located inside the underground field source, the Green's function is singular when the field source point and the observation point are at the same position, which seriously affects the calculation accuracy.

[0003] For the calculation of three components of the magnetic field in a well of a magnetic body with an arbitrary magnetic susceptibility distribution and a complex shape, the general calculation idea is to divide the underground space into many small prisms and accumulate the magnetic fields generated by the small prisms to approximate the magnetic field in the well of the complex magnetic body. The biggest disadvantage of this method is the slow calculation speed. The meshing method and the calculation method together determine the efficiency and accuracy of the calculation of three components of the borehole magnetic field. Calculation efficiency and calculation accuracy are a pair of contradictions. The biggest problem with the accumulation method is that it cannot ensure both calculation efficiency and calculation accuracy at the same time, and cannot meet the requirements of calculation efficiency for joint inversion imaging, human-computer interaction modeling and interpretation of ground-borehole magnetic field data.

[0004] Therefore, it is of great practical significance to find a method for calculating three components of the magnetic field in a well of a magnetic body with high calculation efficiency and ensuring calculation accuracy at the same time. Summary of the Invention

[0005] Aiming at the problem of low calculation accuracy of the existing method for calculating three components of the magnetic field in a well of a magnetic body, and at the same time considering meeting the requirements of calculation efficiency for joint inversion imaging, human-computer interaction modeling and interpretation of ground-borehole magnetic field data, the present invention proposes a method, device, equipment and medium for calculating three components of the magnetic field in a well of a complex magnetic body, which can be adapted to quickly and accurately calculate three components of the magnetic field in a well of a magnetic body with an arbitrary magnetic susceptibility distribution and a complex shape.

[0006] To achieve the above technical objectives, the technical solution proposed by the present invention is as follows:

[0007] On the one hand, the present invention provides a method for calculating three components of the magnetic field in a well of a complex magnetic body, including:

[0008] Determine the target area and construct a prism model that includes the target area inside; perform mesh division on the prism model, dividing it into several small prism units, and assign magnetic susceptibility values to each small prism unit;

[0009] Adopt the three-dimensional discrete convolution method to calculate each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well;

[0010] Based on each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well, obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point in the well.

[0011] Furthermore, in the present invention, the magnetic susceptibility of each small prism unit in the target area is a constant value, and the magnetic susceptibility values of different small prism units are different, so as to depict magnetic bodies with arbitrary magnetic susceptibility distributions and complex shapes. The magnetic susceptibility value of the small prism unit located in the air part is set to zero, so as to depict the undulating terrain.

[0012] Furthermore, the three components of the magnetic field in the well generated by all small prism units at the observation point (x0, y0, z n ) include 9 components, namely b x1 (x0, y0, z n ), b x2 (x0, y0, z n ), b x3 (x0, y0, z n ), b y1 (x0, y0, z n ), b y2 (x0, y0, z n ), b y3 (x0, y0, z n ), b z1 (x0, y0, z n ), b z2 (x0, y0, z n ), and b z3 (x0, y0, z n ), and the calculation formulas are respectively:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022] The horizontal coordinates of the observation points in each well are x0 and y0, and the vertical coordinate of the observation point in each well is z n , n = 1, 2, ..., N, where N is the number of observation points in the well, p = 1, 2, ..., P, where P is the number of subdivisions of the small prism units in the x - direction of the prism model, q = 1, 2, ..., Q, where Q is the number of subdivisions of the small prism units in the y - direction of the prism model, r = 1, 2, ..., R, where R is the number of subdivisions of the small prism units in the z - direction of the prism model, m x (ξ p , η q , ζ r ), m y (ξ p , η q , ζ r ) and m z (ξ p , η q , ζ r ) respectively represent the x - component, y - component, and z - component of the magnetization intensity of the small prism unit with the center - point coordinate position of (ξ p , η q , ζ r ); h1(x0 - ξ p , y0 - η q , z n - ζ r ), h2(x0 - ξ p , y0 - η q , z n - ζ r ), h3(x0 - ξ p , y0 - η q , z n - ζ r ), h4(x0 - ξ p , y0 - η q , z n - ζ r ), h5(x0 - ξ p , y0 - η q , z n - ζ r ), h6(x0 - ξ p , y0 - η q , z n - ζr )、h7(x0 - ξ p , y0 - η q , z n - ζ r )、h8(x0 - ξ p , y0 - η q , z n - ζ r )、h9(x0 - ξ p , y0 - η q , z n - ζ r ) are nine weighting coefficients.

[0023] Further, sum up each component of the three components of the magnetic field in the well generated by all small prism units in the prism model at the observation point (x0, y0, z n ) in the well to obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point (x0, y0, z n ) in the well, that is

[0024] b x (x0, y0, z n ) = b x1 (x0, y0, z n ) + b x2 (x0, y0, z n ) + b x3 (x0, y0, z n )

[0025] b y (x0, y0, z n ) = b y1 (x0, y0, z n ) + b y2 (x0, y0, z n ) + b y3 (x0, y0, z n )

[0026] b z (x0, y0, z n ) = b z1 (x0, y0, z n ) + b z2 (x0, y0, z n ) + b z3 (x0, y0, z n )

[0027] On the other hand, the present invention provides a device for calculating the three components of the magnetic field in a well of a complex magnetic body, including:

[0028] The first module is used to determine the target area, construct a prism model with the target area included therein; perform mesh division on the prism model to divide it into several small prism units, and assign a magnetic susceptibility value to each small prism unit;

[0029] The second module is used to calculate each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point by using the three-dimensional discrete convolution method;

[0030] The third module is used to obtain the three components of the in-well magnetic field generated by the entire prism model at the in-well observation point based on each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point.

[0031] On the other hand, the present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0032] Determine the target area, construct a prism model with the target area included therein; perform mesh division on the prism model to divide it into several small prism units, and assign a magnetic susceptibility value to each small prism unit;

[0033] Calculate each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point by using the three-dimensional discrete convolution method;

[0034] Obtain the three components of the in-well magnetic field generated by the entire prism model at the in-well observation point based on each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point.

[0035] On yet another aspect, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0036] Determine the target area, construct a prism model with the target area included therein; perform mesh division on the prism model to divide it into several small prism units, and assign a magnetic susceptibility value to each small prism unit;

[0037] Calculate each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point by using the three-dimensional discrete convolution method;

[0038] Obtain the three components of the in-well magnetic field generated by the entire prism model at the in-well observation point based on each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point.

[0039] Compared with the prior art, the advantages of the present invention are as follows:

[0040] (1) The prism model representation method proposed by the present invention is simple and flexible, and it is very easy to depict any magnetic susceptibility distribution, complex-shaped magnetic bodies, and undulating terrain;

[0041] (2) The present invention can achieve fast and high-precision calculation of the three components of the magnetic field in a well for complex-shaped magnetic bodies under any magnetic susceptibility distribution and any logging measurement point distribution, and can meet the needs of large-scale surface-well magnetic field data joint inversion, human-computer interaction modeling, and interpretation;

[0042] (3) When performing large-scale calculations, the present invention not only has high calculation efficiency and calculation accuracy, but also requires small computer memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0044] Figure 1 is a flowchart of an embodiment of the present invention;

[0045] Figure 2 is a schematic diagram of a complex magnetic body model in an embodiment of the present invention;

[0046] Figure 3 is a model diagram of a spherical magnetic body in an embodiment of the present invention;

[0047] Figure 4 is the calculated values of the three components of the magnetic field in an embodiment of the present invention, where (a) is the calculated value of the b x component of the three components of the magnetic field, (b) is the calculated value of the b y component of the three components of the magnetic field, (c) is the calculated value of the b z component of the three components of the magnetic field;

[0048] Figure 5 is the theoretical values of the three components of the magnetic field in an embodiment of the present invention, where (a) is the theoretical value of the b x component of the three components of the magnetic field, (b) is the theoretical value of the b y component of the three components of the magnetic field, (c) is the theoretical value of the b z component of the three components of the magnetic field;

[0049] Figure 6 is the relative error between the calculated values and the theoretical values of the three components of the magnetic field in an embodiment of the present invention, where (a) is the relative error between the calculated value and the theoretical value of the b x component of the three components of the magnetic field, (b) is the relative error between the calculated value and the theoretical value of the b yThe relative error between the calculated value and the theoretical value of the component. (c) shows the three components of the magnetic field, where b z The relative error between the calculated value and the theoretical value of the component;

[0050] Figure 7 is a schematic structural diagram of an embodiment of the present invention. Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer and more understandable, the spirit of the content disclosed by the present invention will be clearly described below with reference to the drawings and detailed descriptions. After any person skilled in the art understands the embodiments of the content of the present invention, the technology taught by the content of the present invention can be changed and modified, which does not deviate from the spirit and scope of the content of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention.

[0052] Refer to Figure 1 , in an embodiment of the present invention, a method for calculating the three components of the magnetic field in a well of a complex magnetic body is provided, including:

[0053] (S1) Determine the target area, and construct a prism model that includes the target area inside; perform grid meshing on the prism model, divide it into several small prism units, and assign a magnetic susceptibility value to each small prism unit.

[0054] (S2) Adopt the three-dimensional discrete convolution method to calculate each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well.

[0055] (S3) Based on each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well, obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point in the well.

[0056] In (S1) of the present invention, it is essentially the process of representing a complex magnetic body model, which is specifically as follows:

[0057] Determine the target area, and construct a prism model that includes the target area inside. Determine the starting positions of the prism model in the x, y, and z directions, so that the target area (including the undulating terrain) is completely embedded in the prism model.

[0058] According to the requirements of the actual problem, perform grid meshing on the prism model, and evenly divide it into many regular small prism units. As Figure 2 shown, determine the geometric dimensions Δx, Δy, Δz of the small prism unit, where Δx, Δy, Δz respectively represent the side lengths of the small prism unit in the x direction, y direction, and z direction.

[0059] Assign the magnetic susceptibility to each small prism unit according to the magnetic susceptibility distribution of the target area. The magnetic susceptibility of each small prism unit in the target area is a constant value, and the magnetic susceptibility values of different small prism units are different, so as to characterize magnetic bodies with arbitrary magnetic susceptibility distributions and complex shapes. The magnetic susceptibility value of the small prism unit located in the air part is set to zero to characterize the undulating terrain.

[0060] Thus, the representation of the complex magnetic body model is completed.

[0061] In step (S2) of the present invention, there are multiple observation points in the well. Given the position coordinates (x0, y0, z n ) of each observation point in the well, the horizontal coordinates of the observation point (x0, y0, z n ) in the well are x0 and y0, and the vertical coordinate of the observation point in the well is z n , where n = 1, 2,..., N, and N is the number of observation points in the well.

[0062] In step (S2) of the present invention, calculate each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point. The process includes:

[0063] (S2.1) Calculate the x-component m p of the magnetization intensity of the small prism unit with the center point coordinates (ξ q , η r ), ζ x (ξ p , η q , ζ r ), y-component m y (ξ p , η q , ζ r ), and z-component m z (ξ p , η q , ζ r ).

[0064] (S2.2) Calculate the weighting coefficients h1(x0 - ξ p , y0 - η q , z n - ζ r ), h2(x0 - ξ p , y0 - η q , z n - ζ r ), h3(x0 - ξ p , y0 - η q , z n - ζ r ), h4(x0 - ξ p , y0 - η q , z n - ζr ), h5(x0 - ξ p , y0 - η q , z n - ζ r ), h6(x0 - ξ p , y0 - η q , z n - ζ r ), h7(x0 - ξ p , y0 - η q , z n - ζ r ), h8(x0 - ξ p , y0 - η q , z n - ζ r ), h9(x0 - ξ p , y0 - η q , z n - ζ r ).

[0065]

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[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] where μ0 represents the magnetic permeability of vacuum; arctan() represents the arccotangent function operator, and ln() represents the natural logarithm operator; X1 = ξ p - 0.5Δx - x0, X2 = ξ p + 0.5Δx - x0, Y1 = η q - 0.5Δy - y0, Y2 = η q + 0.5Δy - y0, Z1 = ζ r - 0.5Δz - z n , Z2 = ζ r + 0.5Δz - z n; Δx, Δy, and Δz respectively represent the side lengths of the small prism unit in the x, y, and z directions.

[0075] (S2.3) Use the three-dimensional discrete convolution method to calculate the three components of the magnetic field in the well generated by all small prism units at the observation point in the well.

[0076] The three components of the magnetic field in the well generated by all small prism units at the observation point (x0, y0, z n ) in the well include 9 components, namely b x1 (x0, y0, z n ), b x2 (x0, y0, z n ), b x3 (x0, y0, z n ), b y1 (x0, y0, z n ), b y2 (x0, y0, z n ), b y3 (x0, y0, z n ), b z1 (x0, y0, z n ), b z2 (x0, y0, z n ), and b z3 (x0, y0, z n ). Based on the following calculation formula, use the three-dimensional discrete convolution method to calculate each component of the three components of the magnetic field in the well generated by all small prism units at the observation point in the well:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] where \(p = 1,2,\cdots,P\), \(P\) is the number of subdivisions of the small prismatic elements in the \(x\)-direction of the prismatic model; \(q = 1,2,\cdots,Q\), \(Q\) is the number of subdivisions of the small prismatic elements in the \(y\)-direction of the prismatic model; \(r = 1,2,\cdots,R\), \(R\) is the number of subdivisions of the small prismatic elements in the \(z\)-direction of the prismatic model.

[0087] In step (S3) of the present invention, the three components of the magnetic field in the well generated by all the small prismatic elements in the prismatic model at the well observation point \((x_0,y_0,z\) n ) are respectively accumulated to obtain the three components of the magnetic field in the well generated by the entire prismatic model at the well observation point \((x_0,y_0,z\) n ), that is

[0088] b x (x_0,y_0,z\) n ) = b x1 (x_0,y_0,z\) n ) + b x2 (x_0,y_0,z\) n ) + b x3 (x_0,y_0,z\) n )

[0089] b y (x_0,y_0,z\) n ) = b y1 (x_0,y_0,z\) n ) + b y2 (x_0,y_0,z\) n ) + b y3 (x_0,y_0,z\) n )

[0090] b z (x_0,y_0,z\) n ) = b z1 (x_0,y_0,z\) n ) + b z2 (x_0,y_0,z\) n ) + b z3 (x_0,y_0,z\) n )

[0091] In an embodiment of the present invention, for step (S2.1), to calculate the \(x\)-component \(m\) of the magnetization intensity of the small prismatic element with the center point coordinate position of \((\xi\) p , \eta\) q , \zeta\) r ), \(y\)-component \(m\) x (\xi\) p , \eta\) q , \zeta\) r ), \(z\)-component \(m\) y (\xi\) p , \eta\) q, ζ r ) and the z-component m z (ξ p , η q , ζ r ), including:

[0092] (S2.1.1) According to the International Geomagnetic Reference Field (IGRF) model of the Earth's main magnetic field, calculate the x-component T of the Earth's main magnetic field for a small prismatic element with the central point coordinates (ξ p , η q , ζ r ): x (ξ p , η q , ζ r ), the y-component T y (ξ p , η q , ζ r ) and the z-component T z (ξ p , η q , ζ r ).

[0093] (S2.1.2) According to the magnetic susceptibility κ(ξ p , η q , ζ r ) of a small prismatic element with the central point coordinates (ξ p , η q , ζ r ), calculate the x-component m p , η q , ζ r ), the y-component m x (ξ p , η q , ζ r ) and the z-component m y (ξ p , η q , ζ r ) of the magnetization intensity for a small prismatic element with the central point coordinates (ξ z (ξ p , η q , ζ r ):

[0094] m x (ξ p , η q , ζ r ) = κ(ξ p , η q , ζ r ) · T x (ξ p , η q , ζ r )

[0095] m y (ξ p ,η q ,ζ r )=κ(ξ p ,η q ,ζ r )·T y (ξ p ,η q ,ζ r )

[0096] m z (ξ p ,η q ,ζ r )=κ(ξ p ,η q ,ζ r )·T z (ξ p ,η q ,ζ r )

[0097] In another embodiment of the present invention, the three-dimensional discrete convolution method in step (S2) includes the following steps:

[0098] (1) The weighted coefficient h(x0 - ξ p , y0 - η q , z n - ζ r )(denoted as h1(x0 - ξ p , y0 - η q , z n - ζ r ), h2(x0 - ξ p , y0 - η q , z n - ζ r ), h3(x0 - ξ p , y0 - η q , z n - ζ r ), h4(x0 - ξ p , y0 - η q , z n - ζ r ), h5(x0 - ξ p , y0 - η q , z n - ζ r ), h6(x0 - ξ p , y0 - η q , z n - ζ r ), h7(x0 - ξ p , y0 - ηq , z n , -ζ r ), h8(x0 - ξ p , y0 - η q , z n , -ζ r ), h9(x0 - ξ p , y0 - η q , z n , -ζ r ), any one of which) is arranged into a three - dimensional array t with dimensions P×Q×(R + N - 1). The array element t i,j,k has a relationship with the weighting coefficient h(x0 - ξ p , y0 - η q , z n , -ζ r )

[0099] t i,j,k = h(x0 - ξ i , y0 - η j , z1 - Z k )

[0100] where Z k = z1+(k - N)Δz, k = 1, 2, …, R + N - 1, i = 1, 2, …, P, j = 1, 2, …, Q. P is the number of small prism - shaped elements in the x - direction of the prism model, Q is the number of small prism - shaped elements in the y - direction of the prism model, R is the number of small prism - shaped elements in the z - direction of the prism model, N is the number of observation points in the well, and Δz represents the side length of the small prism - shaped element in its z - direction.

[0101] (2) Arrange the magnetization intensity m(ξ p , η q , ζ r )(p = 1, 2, …, P, q = 1, 2, …, Q, r = 1, 2, …, R, representing m x (ξ p , η q , ζ r ), m y (ξ p , η q , ζ r ), m z (ξ p , η q , ζ r ), any one of which) into a three - dimensional array m with dimensions P×Q×R. The array element m p,q,r has a relationship with the density value

[0102] m p,q,r = m(ξ p , ηq , ζ r )

[0103] Zero-pad the three-dimensional array m to expand it into a three-dimensional array m of size P×Q×(R + N - 1). ext , the three-dimensional array m is located in the first P rows, first Q columns, and first R layers of the three-dimensional array m ext .

[0104] (3) Calculate

[0105] where fft3() represents the three-dimensional fast Fourier transform;

[0106] (4) Calculate

[0107] where ".*" represents the element-wise multiplication operation;

[0108] (5) Calculate

[0109] where ifft3() represents the three-dimensional inverse fast Fourier transform;

[0110] (6) Extract the elements in the first P rows, first Q columns, and first R layers of the three-dimensional array f ext to form a three-dimensional array f, which is the result of the three-dimensional discrete convolution calculation.

[0111] The present invention is an organic whole. A prism model containing the target area is constructed. Using the three-dimensional discrete convolution method, the three components of the magnetic field in the well generated by all small prism elements at the observation point in the well are calculated to obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point in the well. The present invention innovatively proposes the weighting coefficients h1(x0 - ξ p , y0 - η q , z n - ζ r ), h2(x0 - ξ p , y0 - η q , z n - ζ r ), h3(x0 - ξ p , y0 - η q , z n - ζ r ), h4(x0 - ξ p , y0 - η q , z n - ζ r ), h5(x0 - ξ p , y0 - η q , z n - ζ r ), h6(x0 - ξ p , y0 - ηq , z n -ζ r ), h7(x0 - ξ p , y0 - η q , z n -ζ r ), h8(x0 - ξ p , y0 - η q , z n -ζ r ), h9(x0 - ξ p , y0 - η q , z n -ζ r ) The calculation method, by using the above method to calculate 9 weighting coefficients and combining with the three-dimensional discrete convolution fast calculation method, realizes the unification of the calculation accuracy and calculation efficiency of the three components of the magnetic field in the borehole for complex magnetic susceptibility distribution magnetic bodies. The present invention solves the problems of low calculation accuracy and slow calculation speed of the existing calculation methods for the three components of the magnetic field of magnetic bodies in the borehole, and cannot meet the requirements of joint inversion imaging, human-computer interaction modeling and interpretation of surface-borehole magnetic field data.

[0112] Next, the accuracy and efficiency of the calculation method for the three components of the magnetic field in the borehole of complex magnetic bodies provided by the present invention are verified.

[0113] To illustrate the efficiency and accuracy of the method proposed by the present invention for calculating the three components of the magnetic field in the borehole of complex-shaped magnetic bodies under any magnetic susceptibility distribution, a complex magnetic body model as Figure 3 shown is designed.

[0114] A sphere with uniform magnetic susceptibility is embedded in a prism region with constant magnetic susceptibility, and the centers of the prism and the sphere coincide. The range of the prism is: from -1000 m to 1000 m in the x direction, from -1000 m to 1000 m in the y direction, and from 0 m to 1000 m in the z direction (the positive direction of the z-axis is downward); the radius of the sphere is 400 m. The magnetic susceptibility of the prism is 0, and the magnetic susceptibility of the sphere is 0.1 SI. The prism is divided into 200×200×400 cells of the same size. The horizontal coordinates of the observation points in the borehole are (4, 10), the vertical coordinates of the observation points are sampled at equal intervals from 20 m to 980 m, and the number of observation points is 385.

[0115] The algorithm for the three components of the magnetic field in the borehole is implemented by programming in Matlab language. The configuration of the personal desktop computer used to run the program is: the CPU is i7-2620, the main frequency is 2.7 GHz, the memory is 32 GB, and it has four cores and eight threads. The running time required to calculate one component of the magnetic field is about 10 seconds, indicating that the method of the present invention is very efficient. The calculated values of the three components of the magnetic field are as Figure 4 shown, and the theoretical values of the three components of the magnetic field are as Figure 5 shown. From the morphology, the two are consistent, whereFigure 4 In (a), the three components of the magnetic field, and its b x Calculated values of the components, in (b), the three components of the magnetic field, and its b y Calculated values of the components, in (c), the three components of the magnetic field, and its b z Calculated values of the components Figure 5 In (a), the three components of the magnetic field, and its b x Theoretical values of the components, in (b), the three components of the magnetic field, and its b y Theoretical values of the components, in (c), the three components of the magnetic field, and its b z Theoretical values of the components. The relative error is obtained by taking the absolute value of the difference between the theoretical value and the calculated value and dividing it by the theoretical value ( Figure 6 As shown, in (a), the relative error between the calculated value and the theoretical value of the component of the three components of the magnetic field, and its b x In (b), the relative error between the calculated value and the theoretical value of the component of the three components of the magnetic field, and its b y In (c), the relative error between the calculated value and the theoretical value of the component of the three components of the magnetic field, and its b z Relative error of the calculated value and the theoretical value of the component), and the relative errors are statistically analyzed. The statistical results are given in Table 1, indicating that the algorithm has high accuracy.

[0116] Table 1 Statistical analysis of the relative errors between the theoretical values and the calculated values of the three components of the magnetic field

[0117] Maximum value Minimum value Mean value <![CDATA[b x > 0.034 <![CDATA[3.95×10 -6 > 0.0012 <![CDATA[b y > 0.043 <![CDATA[1.10×10 -6 > 0.0019 <![CDATA[b z > 1.47 <![CDATA[9.89×10 -7 > 0.0057

[0118] In another embodiment of the present invention, a device for calculating the three components of the magnetic field in a well of a complex magnetic body is provided, including:

[0119] The first module is used to determine the target area, construct a prism model containing the target area; perform grid meshing on the prism model, divide it into several small prism units, and assign magnetic susceptibility values to each small prism unit;

[0120] The second module is used to calculate each component of the three components of the magnetic field in the well at the observation point in the well by using the three-dimensional discrete convolution method;

[0121] The third module is used to obtain the three components of the magnetic field in the well at the observation point in the well of the entire prism model based on each component of the three components of the magnetic field in the well at the observation point in the well generated by each small prism unit.

[0122] The implementation methods of the functions of the above modules can be implemented by the same methods in the foregoing embodiments, and will not be repeated here.

[0123] In this embodiment, a computer device is provided. The computer device can be a server, and its internal structure diagram can be as Figure 7As shown. The computer device includes a processor, a memory, a network interface, and a database connected by a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store sample data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it realizes the steps of the method for calculating the three components of the magnetic field in a complex magnetic body well in the above-mentioned embodiment.

[0124] Those skilled in the art can understand that Figure 7 the structure shown in is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0125] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it realizes the steps of the method for calculating the three components of the magnetic field in a complex magnetic body well in the above-mentioned embodiment.

[0126] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by the processor, it realizes the steps of the method for calculating the three components of the magnetic field in a complex magnetic body well in the above-mentioned embodiment.

[0127] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0128] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0129] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for calculating three components of the magnetic field in a well with complex magnetic bodies, characterized in that, Including: Determine the target area, and construct a prism model that includes the target area inside; perform mesh division on the prism model to divide it into several small prism units, and assign magnetic susceptibility values to each small prism unit; Using the three-dimensional discrete convolution method, calculate each component of the three components of the in-well magnetic field generated by each small prism unit at the in-well observation point. Each small prism unit at the in-well observation point The three components of the in-well magnetic field generated at the point include 9 components, which are respectively , , , , , , , and , and the calculation formulas are respectively: Among them, the horizontal coordinates of the observation points in each well are x 0, y 0, and the vertical coordinates of the observation points in each well are z n , n = 1, 2,..., N , N where p = 1, 2,..., P , P is the number of observation points in the well, x = 1, 2,..., q , Q , Q is the number of subdivisions of the small prism element in the y direction of the prism model, r = 1, 2,..., R , R is the number of subdivisions of the small prism element in the z direction of the prism model, , and respectively represent the component, x component, and y component of the magnetization intensity of the small prism element with the center point coordinate position of z ; , , , , , , , , are nine weighting coefficients; Based on each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well, obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point in the well.

2. The method for calculating the three components of the magnetic field in a well of a complex magnetic body according to claim 1, wherein The magnetic susceptibility of each small prism unit in the target area is a constant value, and the magnetic susceptibility values of different small prism units are different, so as to characterize magnetic bodies with arbitrary magnetic susceptibility distributions and complex shapes. The magnetic susceptibility value of the small prism unit located in the air part is set to zero to characterize the undulating terrain.

3. The method for calculating the three components of the magnetic field in the well of the complex magnetic body according to claim 1, wherein The coordinate position of the center point is of the magnetization intensity of the small prism unit x component , y component and z component , which is calculated through the following steps: According to the IGRF model of the Earth's main magnetic field, calculate the components of the Earth's main magnetic field of the small prism element with the central point coordinate position x ; , y component and z component ; According to the magnetic susceptibility of the small prism unit with the center point coordinate position , calculate the component of the magnetization intensity of the small prism unit with the center point coordinate position : x component , y component and z component : 。 4. The method for calculating the three components of the magnetic field in a well with a complex magnetic body according to claim 3, wherein Weighting coefficient , , , , , , , , The calculation method is as follows: wherein represents the vacuum permeability; represents the arccotangent function operator, represents the natural logarithm operator; , , , , , ; , , respectively represent the side lengths of the small prism unit in its x direction, y direction, z direction.

5. The method for calculating the three components of the in-well magnetic field of a complex magnetic body according to claim 3, characterized in that Sum up each component of the three components of the in-well magnetic field generated by all small prism units in the prism model at the in-well observation point to obtain the three components of the in-well magnetic field generated by the entire prism model at the in-well observation point i.e., 。 6. The device for calculating three components of the magnetic field in a well with a complex magnetic body, characterized in that, Including: The first module is used to determine the target area, and construct a prism model that includes the target area inside; perform mesh division on the prism model to divide it into several small prism units, and assign magnetic susceptibility values to each small prism unit; The second module is used to calculate each component of the three components of the magnetic field in the well generated by each small prismatic element at the observation point in the well by using the three-dimensional discrete convolution method. The three components of the magnetic field in the well generated by all small prismatic elements at the observation point in the well include 9 components, which are , , , , , , , and , and the calculation formulas are respectively: Among them, the horizontal coordinates of the observation points in each well are x 0, y 0, and the vertical coordinates of the observation points in each well are z n , n = 1, 2,..., N , N where is the number of observation points in the well, p = 1, 2,..., P , P is the number of subdivisions of the small prism element in the x direction of the prism model, q = 1, 2,..., Q , Q is the number of subdivisions of the small prism element in the y direction of the prism model, r = 1, 2,..., R , R is the number of subdivisions of the small prism element in the z direction of the prism model, , and respectively represent the components, x components, and y components of the magnetization intensity of the small prism element with the center point coordinate position of z ; , , , , , , , , are 9 weighting coefficients; The third module is used to obtain the three components of the magnetic field in the well generated by the entire prism model at the observation point in the well based on each component of the three components of the magnetic field in the well generated by each small prism unit at the observation point in the well.

7. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that: When the processor executes the computer program, it implements the steps in the method for calculating the three components of the magnetic field in the well of a complex magnetic body according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps in the method for calculating the three components of the magnetic field in the well of a complex magnetic body according to any one of claims 1 to 5.

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