A method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology

Abstract

A method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology, relating to the field of geophysical exploration. Technical solution: In geodetic coordinates, the lithology and coordinate information in the geological reconnaissance map are used to determine the lithology distribution within the study area; all micrologging points collected within the study area are finely interpreted to obtain velocity information for each point; for all micrologging points within the same lithology area, a triangular mesh is constructed using triangular mesh interpolation and interpolation is performed; the above operation is repeated for all areas with different lithologies within the study area until all lithology areas are completed; for areas where a triangular mesh cannot be formed, the velocity is filled using the average value of adjacent meshes of different lithologies. Beneficial effects: This invention, by combining geological reconnaissance maps and micrologging technology, improves the accuracy of the velocity model, optimizes depth domain imaging effects, and increases production efficiency, providing more reliable technical support for depth domain imaging in oil and gas exploration.

Description

Technical Field

[0001] This invention belongs to the field of velocity modeling and imaging technology in the data processing and interpretation technology of geophysical exploration technology, and particularly relates to a method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology. Background Technology

[0002] Currently, most newly discovered oil and gas reservoirs in my country are located in complex surface areas. The target layers have expanded from shallow and medium-depth to three-dimensional exploration, and the focus has continuously shifted from conventional oil and gas to unconventional oil and gas. Under these complex conditions, near-surface velocity models need to accurately reflect the complexity of near-surface structures and subsurface geological formations to ensure the accuracy and reliability of imaging and meet the needs of geological exploration.

[0003] Under complex conditions, variations in the undulating surface and complex structures such as underground fault zones and normal and reverse faults all affect the propagation and reception of seismic waves. Depth migration technology can reverse-extend seismic information to reconstruct the underground reflected wave field, allowing reflected waves to converge to their reflection interfaces and diffracted waves to the point of diffraction that produced them, thereby obtaining the true location of the reflection interface and acquiring a true image of the underground structure. In the process of ray tracing to determine travel time, regardless of the method used—Kirchhoff Migration, Gaussian ray beam, one-way wave migration, or reverse time migration—depth errors accumulate from shallow to deep. Therefore, in the depth domain, constructing a high-precision near-surface velocity model is particularly important for imaging results.

[0004] In seismic data processing, near-surface velocity models are typically obtained by interpolation using micrologging points within the study area. Micrologging provides more accurate first arrival times of seismic waves, and high-precision data acquisition and interpretation provide more accurate data support for the establishment of near-surface velocity models. For example, Chinese patent CN104749630B discloses a method for constructing a microseismic monitoring velocity model. By considering the influence of strata anisotropy on seismic wave propagation velocity through spatial modeling, a relatively complex velocity model is established to improve the accuracy of microseismic location.

[0005] Due to limitations in acquisition costs and production efficiency, the number of micro-logging wells is usually limited, resulting in sparse control points for near-surface velocity information in the study area. Furthermore, due to the limitations of interpolation methods, traditional linear interpolation methods cannot fully consider the complexity of underground structures and the nonlinear characteristics of velocity changes, which also leads to insufficient accuracy of the near-surface velocity model and poor depth migration imaging results.

[0006] In summary, in oil and gas exploration under complex conditions, the limited number of micro-logging wells, constrained by acquisition costs and production efficiency, leads to sparse control points for near-surface velocity information in the study area. Furthermore, traditional linear interpolation methods cannot fully consider the complexity of underground structures and the nonlinear characteristics of velocity changes, thus affecting the accuracy of the near-surface velocity model and the effect of depth migration imaging. Summary of the Invention

[0007] To address the aforementioned technical problems in existing technologies, this invention provides a method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology. This method involves differentiating the lithology of the study area using geological reconnaissance maps, and then combining micrologging information with velocity modeling within the same lithological region. The resulting velocity model exhibits clear velocity boundaries between different lithological regions. This method can yield a shallow surface velocity model that conforms to real-world conditions and geological principles, and its depth-domain migration can achieve better imaging results.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology, comprising the following steps:

[0010] S1. In geodetic coordinates, the lithology and coordinate information in the geological reconnaissance map are used to determine the lithology distribution within the study area;

[0011] S2. Perform detailed interpretation of all micro-logging points collected within the study area to obtain velocity information for each point;

[0012] S3. For all micro-logging points within the same lithological region, a triangular grid is constructed using the triangular grid interpolation method and interpolation is performed.

[0013] S4. Perform step S3 on all areas with different lithologies within the study area until all lithologies are completed;

[0014] S5. For locations that do not form a triangular grid, the velocity is filled using the average value of adjacent grids with different lithologies.

[0015] Furthermore, in step S3, velocity filling is not performed at locations where triangular meshes are not formed.

[0016] Furthermore, the specific steps of step S1 are as follows:

[0017] S1.1 Establish a planar coordinate system (x, y);

[0018] S1.2 Establish a work area with a rectangular grid of length a and length m×n in the coordinate system;

[0019] The coordinates of the four points of S1.3 and the work area grid are as follows:

[0020] (0,0), (0,n), (m,n), (m,0);

[0021] S1.4. Establish lithological boundaries on the geological map within the work area, assuming the lithological boundary function expression is:

[0022] y = kx + b;

[0023] S1.5, the coordinates of the intersection point of the lithological boundary line and the work area boundary are respectively

[0024] (nb / k, n), -b / k, n);

[0025] S1.6. Based on the geological map, the lithology of the work area is divided into two regions: Lithology Zone 1 and Lithology Zone 2. Near-surface velocity modeling is carried out independently in Lithology Zone 1 and Lithology Zone 2 respectively.

[0026] S1.7 Display the micro-logging points in the work area according to their coordinates in the coordinate system. The coordinates of the micro-logging points are as follows:

[0027] (x1,y1), (x2,y2), (x3,y3),…(x n ,y n ).

[0028] Furthermore, in step S2, the velocity information of adjacent micro-gauge points in the work area is interpolated according to the triangular mesh interpolation method, and the triangular mesh is filled with velocity.

[0029] Furthermore, in step S3, velocity interpolation is performed on the boundary of the work area and the area enclosed by the micro-logging points using the triangular mesh interpolation method.

[0030] Furthermore, in step S3, the rectangular grid portion where the lithological boundary line is located is not filled with velocity.

[0031] Furthermore, in step S4, the above steps are repeated to perform velocity modeling for lithology zone 2.

[0032] Furthermore, after obtaining the velocity models for lithology zone 1 and lithology zone 2, the rectangular grid at the lithology boundary is filled with the average velocity of the adjacent grids in different lithology zones.

[0033] Furthermore, the triangular mesh interpolation method employs the Delaunay triangulation method, with the following steps:

[0034] T1. Determine the total number of pins used to establish the TIN. If the total number is less than 3, report an error and exit.

[0035] T2. Choice of the first point: The first node of the linked list, named Pt1;

[0036] T3. Selection of the second point: satisfying non-Pt1 points; Pt1 is most recently named Pt2;

[0037] T4. Selection of the third point: It satisfies the following conditions: it is not a point Pt1 or Pt2; there are no other nodes inside the circumcircle of the triangle formed with points Pt1 and Pt2; the angle Pt1Pt2Pt3 in the triangle formed with points Pt1 and Pt2 is the largest, so it is named Pt3;

[0038] T5. Generate three edges and add them to the edge table;

[0039] T6. Generate the first triangle and build the triangle table.

[0040] Further steps to expand the TIN table are as follows:

[0041] U1. Take one edge from the edge list header and require that the flag of that edge is false.

[0042] U2. Search for a point in the point list with the following requirements: Pixel3 on the opposite side of the edge; no other points are inside the circumcircle of the triangle formed by the point and the edge; among the points that satisfy the above two conditions, the point with the largest angle Pt1Pt2Pt3 is Pt3.

[0043] U3. Determine the newly generated edge. If it is not in the edge table, add it to the end of the edge table and set the flag to false. If it is, set the flag of the edge to true.

[0044] U4. Add the generated triangles to the triangle table;

[0045] U5. Set the flag of the selected edge to true;

[0046] U6. Proceed to step U1 until all the flags of the edge table are true.

[0047] The beneficial effects of this invention are:

[0048] Compared with existing technologies, this method identifies areas with different lithologies within the study area using geological reconnaissance maps, and then uses micrologging information to model near-surface velocities within the same lithology area. Analysis comparing the velocity slices of models obtained using conventional methods with those obtained using the new method reveals that the shallow surface velocity model established by conventional methods only relates to the mathematical laws of the interpolation method and does not conform to real geological conditions. In contrast, the velocity model established using this invention better reflects real geological conditions, resulting in more accurate and reliable results. This invention obtains a more precise near-surface velocity model, which can provide better imaging effects for subsequent depth domain processing. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology described in this invention also has the following technical features or beneficial effects:

[0049] (1) Improved accuracy of velocity model: By combining geological reconnaissance maps and micrologging technology, this invention can more accurately determine the lithological distribution within the study area and perform velocity modeling using triangular mesh interpolation within the same lithological area. It fully considers the complexity of underground structures and the nonlinear characteristics of velocity changes, thereby significantly improving the accuracy of the near-surface velocity model.

[0050] (2) Conforms to real geological conditions: Compared with existing technologies, the shallow surface velocity model established in this invention not only relies on the mathematical laws of interpolation methods, but also fully considers real geological conditions. By distinguishing lithology through geological reconnaissance maps and forming clear velocity boundaries between different lithology regions, the velocity model is more consistent with the real underground structure.

[0051] (3) Optimizing depth domain imaging: Using the high-precision near-surface velocity model obtained in this invention for depth domain migration processing can yield better imaging results. This helps to more accurately identify the location and morphology of underground oil and gas reservoirs in oil and gas exploration, thereby improving the success rate and efficiency of exploration.

[0052] (4) Reduce acquisition costs: By using more accurate speed modeling, the number of micro-logging points can be reduced to a certain extent, thereby reducing exploration costs to a certain extent.

[0053] (5) Improve production efficiency: The method of the present invention has clear steps and is easy to implement. It can automate or semi-automatically process data and model, thereby significantly improving the production efficiency of oil and gas exploration.

[0054] In summary, this invention provides an effective method for establishing a high-precision near-surface velocity model by combining geological reconnaissance maps and micrologging technology, providing more reliable technical support for depth domain imaging in oil and gas exploration. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0056] Figure 1 This is a planar coordinate system diagram of the present invention;

[0057] Figure 2 This is a diagram of the study area in the coordinate system of this invention;

[0058] Figure 3 This is a schematic diagram of the four-point coordinates of the grid of the present invention;

[0059] Figure 4 This is a schematic diagram illustrating the establishment of lithological boundaries in this invention;

[0060] Figure 5 This is a schematic diagram showing the coordinates of the intersection point between the lithological boundary line and the work area boundary of this invention;

[0061] Figure 6 This is a schematic diagram of lithology zone 1 and lithology zone 2 of the present invention;

[0062] Figure 7 This is a schematic diagram of the micro-gauge well point coordinates of the present invention;

[0063] Figure 8 This is a schematic diagram of the triangular mesh velocity filling of the present invention. Figure 1 ;

[0064] Figure 9 This is a schematic diagram of the triangular mesh velocity filling of the present invention. Figure 2 ;

[0065] Figure 10 This is a schematic diagram of the average velocity filling between adjacent grids in this invention;

[0066] Figure 11 This is a schematic diagram illustrating the effect of implementing the present invention. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The following description, in conjunction with the accompanying drawings... Figure 1-11 The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology is further explained, and the technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] Example 1

[0069] The purpose of this invention is to provide a method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology. Currently, most of the near-surface velocity models used are obtained by methods such as micrologging interpolation smoothing, first-arrival tomography inversion, and micrologging constrained tomography. These methods all perform numerical analysis from a mathematical perspective, using either interpolation or constraints, and cannot take into account actual geological factors.

[0070] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0071] A method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology, the method comprising the following steps:

[0072] 1. In geodetic coordinates, the lithology and coordinate information in the geological reconnaissance map are used to determine the lithology distribution within the study area;

[0073] 2. Perform detailed interpretation of all micro-logging points collected within the study area to obtain velocity information for each point;

[0074] 3. For all micro-logging points within the same lithological region, a triangular mesh is constructed using the Delaunay triangulation method and interpolation is performed. No velocity filling is performed at locations where a triangular mesh is not constructed (i.e., at lithological boundaries).

[0075] 4. Repeat step 3 for all areas with different lithologies within the study area until all lithology areas are completed;

[0076] 5. For areas that do not form a triangular grid (i.e., lithological boundaries), the average value of adjacent grids of different lithologies is used for velocity filling.

[0077] Example 2

[0078] Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0079] This specific implementation adopts the following technical solution: a method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology, with a simplified geological reconnaissance map, study area grid, and micrologging information as a simple implementation example, including the following steps:

[0080] 1. For example Figure 1 As shown, the planar coordinate system is (x, y);

[0081] 2. For example Figure 2 As shown, the study area contains an m×n rectangular grid with side length a located at... Figure 1 In the coordinate system;

[0082] 3. For example Figure 3 As shown, the coordinates of the four points on the grid are respectively

[0083] (0,0), (0,n), (m,n), (m,0);

[0084] 4. For example Figure 4 As shown, the lithological boundary line on the geological map passes through the interior of the work area, and it can be assumed that the functional expression of the lithological boundary line is:

[0085] y = kx + b;

[0086] 5. For example Figure 5 As shown, the coordinates of the intersection point of the lithological boundary line and the work area boundary are respectively...

[0087] (nb / k, n), (-b / k, n);

[0088] 6. For example Figure 6 As shown, the geological map can be used to divide the work area into two regions based on lithology: Lithology Zone 1 and Lithology Zone 2. Near-surface velocity modeling can be performed independently in Lithology Zone 1 and Lithology Zone 2 respectively.

[0089] 7. For example Figure 7 As shown, the micro-logging points in the study area are displayed in a coordinate system according to their coordinates. The coordinates of the micro-logging points are as follows:

[0090] (x1,y1), (x2,y2), (x3,y3),…;

[0091] 8. For example Figure 8 As shown, the velocity information of adjacent micro-gauge well points in the work area is interpolated according to the triangular mesh interpolation method, and the triangular mesh is filled with velocity.

[0092] 9. For example Figure 9 As shown, since there are micro-gauge well points at the boundary of the work area, the triangular mesh interpolation method can be used to interpolate the velocity of the area enclosed by the boundary of the work area and the micro-gauge well points. However, there is a possibility that the micro-gauge well points in lithology zone 1 and the lithological boundary line cannot form a triangular mesh. Therefore, the rectangular mesh part where the lithological boundary line is located will not be filled with velocity for the time being.

[0093] 10. Repeat the above steps to perform velocity modeling for lithology zone 2;

[0094] 11. For example Figure 10 As shown, after obtaining the velocity models of lithology zone 1 and lithology zone 2, the rectangular grid where the lithology boundary line is located is filled with the average value of the adjacent grid velocities of different lithology zones.

[0095] In practical applications, the coordinates of the lithological boundary lines, microgauge well points, and the grid coordinates of the study area on the geological reconnaissance map are all in geodetic coordinates. Lithology can be distinguished by coordinates based on the geological reconnaissance map, and interpolation can be performed within the same lithological region based on the coordinates and velocity information of the microgauge well points.

[0096] The triangular mesh interpolation method in this invention adopts the Delaunay triangulation method. The triangular meshes satisfy the principles of empty circularity and minimum angle maximization, and also satisfy local optima. The implementation steps are detailed in Example 3.

[0097] The specific implementation effects of this invention are as follows: Figure 11As shown, the left image is a slice of the velocity model obtained by applying this invention from a top-down perspective, while the right image is obtained by a conventional method. Both images cover the same area and have the same depth. A comparison reveals that the left image has clear velocity boundaries, clearly distinguished by geological factors (different lithology), while the right image shows a significant transition zone that does not reflect real geological conditions. Therefore, the method used in this invention can obtain a shallow surface velocity model that is more consistent with reality and geological laws.

[0098] Example 3

[0099] This embodiment provides the specific steps of the triangular mesh interpolation method.

[0100] The triangular mesh interpolation method in this invention employs the Delaunay triangulation method. The Delaunay triangulation method is widely used in computer graphics, computational geometry, and numerical analysis. Its triangulation triangles satisfy the principles of open circularity, minimizing angles, and local optima.

[0101] The Delaunay triangulation method can convert discrete micro-logging points within a work area into a triangular mesh, facilitating interpolation analysis of micro-logging velocity information on this mesh. A key characteristic of Delaunay triangulation is that the circumcircle of each triangulation does not contain any other reference points. Utilizing this property, we can directly construct a Delaunay triangulation. The specific implementation steps are as follows:

[0102] Establish the first triangle

[0103] 1. Determine the total number of pins used to create the TIN; if it is less than 3, report an error and exit.

[0104] 2. Selection of the first node: The first node of the linked list, named Pt1;

[0105] 3. The choice of the second point:

[0106] It must be a non-Pt1 point;

[0107] Pt1 was recently renamed Pt2.

[0108] 4. The choice of the third point:

[0109] Points other than Pt1 and Pt2;

[0110] The circumcircle of the triangle formed by points Pt1 and Pt2 has no other nodes.

[0111] The triangle formed by points Pt1, Pt2, and Pt3 has the largest angle Pt1Pt2Pt3, so it is named Pt3.

[0112] 5. Generate three edges and add them to the edge table;

[0113] 6. Generate the first triangle and build the triangle table.

[0114] Extended TIN table

[0115] 1. Take one edge from the edge list header, with the requirement that the edge's flag is false (it exists only in one triangle);

[0116] 2. Search for a point in a linked list, with the following requirements:

[0117] Pixel 3 is on the opposite side of the edge;

[0118] There are no other points inside the circumcircle of the triangle formed by this point and the side.

[0119] Among the points that satisfy the above two conditions, the point with the largest angle Pt1Pt2Pt3 is Pt3.

[0120] 3. Check the newly generated edge. If it is not in the edge table, add it to the end of the edge table and set its flag to false. If it is present, set the edge's flag to true.

[0121] 4. Add the generated triangles to the triangle table;

[0122] 5. Set the flag of the selected edge to true;

[0123] 6. Go back to step 1 until all the flags on the edge table are true.

[0124] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0125] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of software products. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0127] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology, characterized in that, The steps are as follows: S1. In geodetic coordinates, the lithology and coordinate information in the geological reconnaissance map are used to determine the lithology distribution within the study area; S2. Perform detailed interpretation of all micro-logging points collected within the study area to obtain velocity information for each point; S3. For all micro-logging points within the same lithological region, a triangular mesh is constructed using the triangular mesh interpolation method and interpolation is performed. S4. Perform step S3 on all areas with different lithologies within the study area until all lithologies are completed; S5. For locations that do not form a triangular grid, the velocity is filled using the average value of adjacent grids with different lithologies.

2. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 1, characterized in that, In step S3, velocity filling is not performed where triangular meshes are not formed.

3. The method for establishing a surface velocity model using geological reconnaissance maps and micro-logging technology as described in claim 1, characterized in that, The specific steps of step S1 are as follows: S1.1 Establish a planar coordinate system (x, y); S1.2 Establish a work area with a rectangular grid of length a and length m×n in the coordinate system; S1.3, the coordinates of the four points of the work area grid are (0,0), (0,n), (m,n), and (m,0); S1.

4. Establish lithological boundaries on the geological map within the work area, assuming the lithological boundary function expression is: y = kx + b; S1.5, the coordinates of the intersection point of the lithological boundary line and the work area boundary are respectively (nb / k, n), (-b / k, n); S1.

6. Based on the geological map, the lithology of the work area is divided into two regions: Lithology Zone 1 and Lithology Zone 2. Near-surface velocity modeling is carried out independently in Lithology Zone 1 and Lithology Zone 2 respectively. S1.7 Display the micro-logging points in the work area according to their coordinates in the coordinate system. The coordinates of the micro-logging points are as follows: (x1,y1)、(x2,y2)、(x3,y3)、…(x n ,y n )。 4. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 1, characterized in that, In step S2, the velocity information of adjacent micro-gauge well points in the work area is interpolated according to the triangular mesh interpolation method, and the triangular mesh is filled with velocity.

5. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 3, characterized in that, In step S3, velocity interpolation is performed on the boundary of the work area and the area enclosed by the micro-logging points using the triangular mesh interpolation method.

6. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 3, characterized in that, In step S3, the rectangular grid portion where the lithological boundary line is located is not filled with velocity.

7. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 3, characterized in that, In step S4, repeat the above steps to perform velocity modeling for lithology zone 2.

8. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 7, characterized in that, After obtaining the velocity models for lithology zones 1 and 2, the rectangular grid at the lithology boundary is filled with the average velocity of adjacent grids in different lithology zones.

9. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 7, characterized in that, The triangular mesh interpolation method uses the Delaunay triangulation method, and the steps are as follows: T1. Determine the total number of pins used to establish the TIN. If the total number is less than 3, report an error and exit. T2. Choice of the first point: The first node of the linked list, named Pt1; T3. Selection of the second point: satisfying non-Pt1 points; Pt1 is most recently named Pt2; T4. Selection of the third point: It satisfies the following conditions: it is not a point Pt1 or Pt2; there are no other nodes inside the circumcircle of the triangle formed with points Pt1 and Pt2; the angle Pt1Pt2Pt3 in the triangle formed with points Pt1 and Pt2 is the largest, so it is named Pt3; T5. Generate three edges and add them to the edge table; T6. Generate the first triangle and build the triangle table.

10. The method for establishing a surface velocity model using geological reconnaissance maps and micrologging technology as described in claim 9, characterized in that, The steps to expand the TIN table are as follows: U1. Take one edge from the edge list header and require that the flag of that edge is false. U2. Search for a point in the point list with the following requirements: Pixel3 on the opposite side of the edge; no other points are inside the circumcircle of the triangle formed by the point and the edge; among the points that satisfy the above two conditions, the point with the largest angle Pt1Pt2Pt3 is Pt3. U3. Determine the newly generated edge. If it is not in the edge table, add it to the end of the edge table and set the flag to false. If it is, set the flag of the edge to true. U4. Add the generated triangles to the triangle table; U5. Set the flag of the selected edge to true; U6. Proceed to step U1 until all the flags of the edge table are true.

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