A method and system for calculating the number of multiple wave coverages based on layered medium

Abstract

The application provides a layered medium-based multiple wave coverage times calculation method and system, and belongs to the field of well seismic exploration.The method comprises the following steps: step S1, inputting parameters;step S2, creating a coverage times statistical bin grid;step S3, calculating the multiple wave reflection point position of one shot point at one bin depth and mapping to the bin grid;step S4, calculating the multiple wave reflection point position of one shot point at each bin depth and mapping to the bin grid;step S5, calculating the multiple wave reflection point position of each shot point at each horizon and mapping to the bin grid.The method has fast calculation efficiency and high calculation precision, and has innovation and practicability in well VSP acquisition design.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of borehole seismic exploration, and particularly relates to a multiple wave coverage times calculation method and system based on layered medium. BACKGROUND

[0002] Vertical Seismic Profile (VSP) has the characteristics of high signal-to-noise ratio and high resolution due to the characteristics of receiving in the well, and it has the advantages of wide ray path and large imaging range in the first-order surface multiple waves, and has special application in the field of seismic exploration, such as reconstructing the multiple wave record into a ground seismic record for imaging by VSP direct wave and surface first-order multiple wave interference, thereby expanding the imaging range of VSP and finely imaging special structures near the well.

[0003] The acquisition design in VSP multiple wave exploration is the premise of ensuring the exploration effect, and the calculation of multiple wave coverage times is a key step in the acquisition design. At present, there is no method for calculating the coverage times of VSP multiple waves in actual application, therefore, it is an urgent problem to be solved to seek a method for calculating the coverage times of VSP multiple waves. SUMMARY

[0004] The application aims to solve the problems in the prior art, and provides a multiple wave coverage times calculation method and system based on layered medium, which takes into account the calculation efficiency and accuracy.

[0005] The application is implemented by the following technical solutions:

[0006] In a first aspect, the application provides a multiple wave coverage times calculation method based on layered medium, comprising the following steps:

[0007] Step S1, input parameters;

[0008] Step S2, create a coverage times statistical bin grid;

[0009] Step S3, calculate the multiple wave reflection point position of one shot point at one bin depth, and map it to the bin grid;

[0010] Step S4, calculate the multiple wave reflection point position of one shot point at each bin depth, and map it to the bin grid;

[0011] Step S5, calculate the multiple wave reflection point position of each shot point at each horizon, and map it to the bin grid.

[0012] Further improvements of the application are as follows:

[0013] The input parameters in step S1 specifically include:

[0014] Input model parameters (h) i ,v i ), i = 1, 2 ... I, where I is the model layer number, h i v represents the layer depth of the reflected wave in the i-th layer. i This represents the layer velocity of the reflected wave in the i-th layer;

[0015] Input the locations of all excitation points involved in the calculation (x sm ,h sm ), where m = 1, 2...M; receiver location (x gn ,h gn ), where n = 1, 2, ..., N; M and N are the number of excitation points and receiver points, respectively; x represents the horizontal coordinate and h represents the depth coordinate;

[0016] Input surface grid spacing d x and d h ; where d x d h These represent the horizontal width and vertical height of the element mesh, respectively.

[0017] A further improvement of the present invention is that:

[0018] The creation of the coverage count statistical element mesh in step S2 includes the following specific operations:

[0019] Calculate the horizontal range x of the surface element mesh max =x sM -x g1 Vertical range h max =h I -h1; where x g1 This represents the x-coordinate of the first receiver point. sM This represents the x-coordinate of the last excitation point, where h I h1 represents the depth of the last layer of the model, and h1 represents the depth of the first layer of the model.

[0020] Calculate the number of horizontal surface elements K = x max / d x The number of vertical facet grid elements L = h max / d h ;

[0021] x max Divide the surface into K equal parts and number them b. xk k = 1, 2...K; The vertical range h of the surface element mesh max Divide into L equal face elements and number them b. hl l = 1, 2, ..., L;

[0022] Each face grid (b) xk ,bhl The initial value for the number of coverages is set to 0.

[0023] A further improvement of the present invention is that:

[0024] In step S3, the location of the multiple wave reflection point at a shot receiver point at a depth of one element is calculated and mapped to the element mesh. Specific operations include:

[0025] Step S301: Select the first excitation point (x) s1 ,h s1 From the excitation point depth h s1 The depth h from the start of the layer to the first vertical element r1 Calculate the vertical propagation path s of the ray through each layer. si , where i = 1, 2 ... N, and N is the number of layers the ray passes through;

[0026] Step S302: Calculate the vertical travel time t of seismic waves at each layer. si =s si / v i Where i = 1, 2...N, and N is the number of layers the ray passes through;

[0027] Step S303: Calculate the vertical incidence time t from the first excitation point to the depth of the first vertical element. 0sr :

[0028]

[0029] Step S304: Calculate the root mean square velocity v from the first excitation point to the depth of the first vertical element. sr :

[0030]

[0031] Step S305: Take the first receiving point (x) g1 ,h g1 From the depth h of the first excitation point in step S301 s1 The depth h from the start of the layer to the first receiving point g1 Calculate the vertical propagation path s of the ray through each layer. gi , where i = 1, 2 ... N, and N is the number of layers the ray passes through;

[0032] Step S306: Calculate the vertical travel time for each layer. Where i = 1, 2...N, and N is the number of layers the ray passes through;

[0033] Step S307: Calculate the vertical incidence time t from the depth of the first excitation point to the first receiver point. 0sg :

[0034]

[0035] Step 308: Calculate the root mean square velocity v at the depth from the first excitation point to the first receiver point. sg :

[0036]

[0037] Step S309: Calculate the first excitation point (x) s1 ,h s1 ) to the first receiving point (x) gn ,h gn The location of the multiple reflection point at the depth of the first vertical element.

[0038] Where, x s and x g These represent the x-coordinates of the excitation point and the receiver point, respectively.

[0039] Step S310: Position the multiple reflection point x r Mapped to surface mesh (b xk ,b h1 And increment the coverage count by 1, where k = x r / dx.

[0040] A further improvement of the present invention is that:

[0041] In step S4, the positions of multiple wave reflection points at each surface depth of a shot receiver are calculated and mapped to the surface mesh. Specific operations include:

[0042] Following steps S301 to S310, traverse the depths of all vertical surface element meshes and calculate the first excitation point (x). s1 ,h s1 ) to the first receiving point (x) g1 ,h g1 Map the positions at all vertical facet mesh depths and update the corresponding coverage counts.

[0043] A further improvement of the present invention is that:

[0044] In step S5, the positions of multiple wave reflection points at each layer for each shot receiver are calculated and mapped to a surface mesh. Specific operations include:

[0045] Repeat steps S3 and S4 to traverse all excitation and receiver positions, calculate the surface mapping positions from all excitation points to all receiver points at all surface depths, and update the coverage count.

[0046] The final updated coverage count is the obtained multi-wave coverage count.

[0047] A further improvement of the present invention is that:

[0048] The method further includes step S6, outputting the coverage count profile, specifically:

[0049] The surface mesh (b) mapped in step S5 xk ,b hl In ), b xk The horizontal coordinate x-value is the x-coordinate, b hl The vertical coordinate h is the ordinate, and the graph is plotted, with the color intensity representing the number of times the position is covered.

[0050] A second aspect of the present invention provides a system for calculating the number of wave coverages based on layered media, comprising:

[0051] The input module is used to input parameters;

[0052] Create a module for creating coverage count statistics cell meshes;

[0053] The first calculation module is used to calculate the position of the multiple wave reflection point at a shot receiver at a depth of one surface cell and map it to the surface cell mesh.

[0054] The second calculation module is used to calculate the position of the multiple wave reflection point at each surface depth of a shot receiver and map it to the surface mesh.

[0055] The third calculation module is used to calculate the location of multiple wave reflection points at each layer for each shot receiver and map them to a surface mesh.

[0056] A third aspect of the present invention provides a computer-readable medium storing at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the method for calculating the number of multiple wave coverages based on layered media as described above.

[0057] A fourth aspect of the present invention provides a computer device including a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method for calculating the number of multiple wave coverages based on layered media as described above.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] The method of this invention has both fast computational efficiency and high computational accuracy, and is innovative and practical in the design of VSP acquisition in wells. Attached Figure Description

[0060] Figure 1 This is a flowchart of a method for calculating the number of wave coverages based on layered media provided by the present invention;

[0061] Figure 2 This is a schematic diagram of the method of the present invention;

[0062] Figure 3 This is a cross-sectional view of the number of wave coverages;

[0063] Figure 4 This is a multi-wave ray path diagram when the surface mesh depth is 7420 meters;

[0064] Figure 5 It is the number of wave coverages for each element when the element grid depth is 7420 meters;

[0065] Figure 6 This is a multi-wave ray path diagram when the surface mesh depth is 8110 meters;

[0066] Figure 7 It is the number of wave coverages of each element when the element grid depth is 8110 meters. Detailed Implementation

[0067] The present invention will now be described in further detail with reference to the accompanying drawings:

[0068]

Example 1

[0069] This invention provides a method for calculating the number of wave multiples based on layered media, such as... Figure 1 and Figure 2 As shown, the specific steps include:

[0070] Step S1: Input parameters;

[0071] Specifically, it includes:

[0072] Input model parameters (h) i ,v i ), i = 1, 2 ... I, where I is the model layer number, h i v represents the layer depth of the reflected wave in the i-th layer. i This represents the layer velocity of the reflected wave in the i-th layer;

[0073] Input the locations of all excitation points involved in the calculation (x sm ,h sm ), where m = 1, 2...M; receiver location (x gn ,h gn ), where n = 1, 2, ..., N; M and N are the number of excitation points and receiver points, respectively; x represents the horizontal coordinate and h represents the depth coordinate;

[0074] Input surface grid spacing d x and d h ; where d x d h These represent the horizontal width and vertical height of the element mesh, respectively.

[0075] Step S2: Create a coverage count statistics mesh;

[0076] The specific operations include:

[0077] Calculate the horizontal range x of the surface element mesh max =x sM -x g1 Vertical range h max =h I -h1; where x g1 This represents the x-coordinate of the first receiver point. sM Let h represent the x-coordinate of the Mth (last) excitation point, where h I h1 represents the depth of the last layer of the model, and h1 represents the depth of the first layer of the model.

[0078] Calculate the number of horizontal surface elements K = x max / d x The number of vertical facet grid elements L = h max / d h ;

[0079] x max Divide the surface into K equal parts and number them b. xk k = 1, 2...K; The vertical range h of the surface element mesh max Divide into L equal face elements and number them b. hl l = 1, 2, ..., L;

[0080] Each face grid (b) xk ,b hl The initial value for the number of coverages is set to 0.

[0081] Step S3: Calculate the position of the multiple reflection point of a shot receiver at a depth of one surface cell and map it to the surface cell mesh;

[0082] The specific operations include:

[0083] Step S301: Select the first excitation point (x) s1 ,h s1 From the excitation point depth h s1 The depth h from the start of the layer to the first vertical element r1 Calculate the vertical propagation path s of the ray through each layer. si , where i = 1, 2 ... N, and N is the number of layers the ray passes through;

[0084] Step S302: Calculate the vertical travel time t of seismic waves at each layer. si =s si / v i Where i = 1, 2...N, and N is the number of layers the ray passes through;

[0085] Step S303: Calculate the vertical incidence time t from the first excitation point to the depth of the first vertical element. 0sr :

[0086]

[0087] Step S304: Calculate the root mean square velocity v from the first excitation point to the depth of the first vertical element. sr :

[0088]

[0089] Step S305: Take the first receiving point (x) g1 ,h g1 From the depth h of the first excitation point in step S301 s1 The depth h from the start of the layer to the first receiving point g1 Calculate the vertical propagation path s of the ray through each layer. gi , where i = 1, 2 ... N, and N is the number of layers the ray passes through;

[0090] Step S306: Calculate the vertical travel time for each layer. Where i = 1, 2...N, and N is the number of layers the ray passes through;

[0091] Step S307: Calculate the vertical incidence time t from the depth of the first excitation point to the first receiver point. 0sg :

[0092]

[0093] Step 308: Calculate the root mean square velocity v at the depth from the first excitation point to the first receiver point. sg :

[0094]

[0095] Step S309: Calculate the first excitation point (x) s1 ,h s1 ) to the first receiving point (x) gn ,h gn The location of the multiple reflection point at the depth of the first vertical element.

[0096] Where, xs and x g These represent the x-coordinates of the excitation point and the receiver point, respectively.

[0097] Step S310: Position the multiple reflection point x r Mapped to surface mesh (b xk ,b h1 And increment the coverage count by 1, where k = x r / dx.

[0098] Step S4: Calculate the position of the multiple wave reflection point at each surface depth of a shot receiver and map it to the surface mesh;

[0099] The specific operations include:

[0100] Following steps S301 to S310, traverse the depths of all vertical surface element meshes and calculate the first excitation point (x). s1 ,h s1 ) to the first receiving point (x) g1 ,h g1 Map the positions at all vertical facet mesh depths and update the corresponding coverage counts.

[0101] Step S5: Calculate the location of multiple wave reflection points at each layer for each shot receiver and map them to a surface mesh;

[0102] Repeat steps S3 and S4 to traverse all excitation and receiver locations, calculate the surface mapping positions from all excitation points to all receiver points at all surface depths, and update the coverage count.

[0103] The final updated coverage count is the obtained multi-wave coverage count.

[0104] Step S6: Output the coverage count profile:

[0105] Specifically, the result of the calculation step S5 in the third step is plotted as a graph, specifically the surface mesh (b) mapped in step S5. xk ,b hl In ), b xk The horizontal coordinate x-value is the x-coordinate, b hl The vertical coordinate h is the ordinate, and the graph is plotted, with the color intensity representing the number of times the position is covered.

[0106] Table 1 shows the model parameters for the embodiment, including layer depth and layer velocity.

[0107] Table 1

[0108] Serial number 1 2 3 4 5 6 7 8 9 10 11 Layer depth (m) 0 1982 3260 3845 4445 6225 7420 8110 9210 10127 10950 Longitudinal wave velocity (m / s) 1953 1953 2819 3803 4203 4604 4806 5770 6453 6714 5789

[0109] Figure 3In the model of the embodiment in Table 1, the surface mesh d x and d h Both are 10 meters, with an excitation point depth of h. s =0, position x s The receiver location x varies from 0 to 6000 meters (in increments of 10 meters). g =0, depth h g Profile of the number of times the cover changes from 6000 to 7500 meters (increment of 10 meters).

[0110] Figure 4 yes Figure 3 When calculating the number of coverages, the output is the ray path map when the depth of the facet mesh is 7440 meters.

[0111] Figure 5 yes Figure 3 Coverage number map extracted from the cross-section when the depth of the surface cell mesh is 7440 meters.

[0112] Figure 6 yes Figure 3 When calculating the number of coverages, the output is the ray path map when the depth of one of the facet meshes is 8110 meters.

[0113] Figure 7 yes Figure 3 Coverage number map when the depth of the surface cell mesh is 8110 meters, extracted from the cross section.

[0114] From the above Figures 3-7 As shown in the figure, the multiple coverage profile calculated by this invention reflects a reasonable multiple illumination coverage range, and the ray path conforms to the multiple propagation law. The differences in multiple ray paths and coverage at different grid depths reflect the illumination coverage of the observation system at different target layer depths, indicating that this method can correctly calculate the multiple observation coverage. In addition, due to the use of the analytical formula for layered media, the calculation in this embodiment only takes 5-8 seconds, indicating that the calculation efficiency of this invention is very high, demonstrating its practicality and effectiveness.

[0115]

Example 2

[0116] This invention provides a system for calculating the number of wave multiples of coverage based on layered media, comprising:

[0117] The input module is used to input parameters;

[0118] Create a module for creating coverage count statistics cell meshes;

[0119] The first calculation module is used to calculate the position of the multiple wave reflection point at a shot receiver at a depth of one surface cell and map it to the surface cell mesh.

[0120] The second calculation module is used to calculate the position of the multiple wave reflection point at each surface depth of a shot receiver and map it to the surface mesh.

[0121] The third calculation module is used to calculate the location of multiple wave reflection points at each layer for each shot receiver and map them to a surface mesh.

[0122] The device also includes an output module for outputting a coverage profile.

[0123]

Example 3

[0124] This invention provides a computer-readable medium storing at least one computer-executable program. When executed by the computer, the at least one program causes the computer to perform the steps in the above-described method for calculating the number of multiple wave coverages based on layered media.

[0125]

Example 4

[0126] This invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the multi-wave coverage number calculation method based on layered media as described above.

[0127] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory 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), dual data rate SDRAM (DDRSDRAM), 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 above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only a preferred option and is not restrictive.

Claims

1. A method for calculating the number of wave coverages based on layered media, characterized in that, Includes the following steps: Step S1: Input parameters; Step S2: Create a coverage count statistics mesh; Step S3: Calculate the position of the multiple reflection point of a shot receiver at a depth of one surface element and map it to the surface element mesh; Step S4: Calculate the position of the multiple wave reflection point at each surface depth of a shot receiver and map it to the surface mesh; Step S5: Calculate the location of multiple wave reflection points for each shot receiver at each layer and map them to a surface mesh; The input parameters in step S1 specifically include: Input model parameters ( h i , v i ), i =1,2…… I , I For the number of model layers, h i This represents the layer depth of the reflected wave in the i-th layer. v i This represents the layer velocity of the reflected wave in the i-th layer; Enter the locations of all excitation points involved in the calculation ( x sm , h sm ),in m =1,2…… M Location of receiving point ( x gn , h gn ),in n =1,2…… N ; M , N These represent the number of excitation points and the number of receiving points, respectively. x Represents the coordinates in the horizontal direction. h Coordinates representing the depth direction; Input the surface mesh size d x and d h ;in, d x , d h These represent the horizontal width and vertical height of the element mesh, respectively; The creation of the coverage count statistical element mesh in step S2 includes the following specific operations: Calculate the horizontal range of the surface element mesh x max = x sM - x g1 Vertical range h max = h I - h 1; among which, x g1 This represents the x-coordinate of the first receiving point. x sM This represents the x-coordinate of the last excitation point, where h I The depth of the last layer of the model. h 1 represents the depth of the first layer of the model; Calculate the number of horizontal surface elements K = x max / d x and the number of vertical facet grid elements L = h max / d h ; Horizontal range of the surface grid x max Divided into equal parts K Each face element is numbered as follows: b xk , k =1,2…… K ; Vertical range of the element mesh h max Divided into equal parts L Each face element is numbered as follows: b hl , l =1,2…… L ; Each face grid ( b xk , b hl The initial value for the number of coverages is set to 0; In step S3, the location of the multiple reflection point of a shot receiver at a depth of one element is calculated and mapped to the element mesh. Specific operations include: Step S301: Select the first excitation point ( x s1 , h s1 From the depth of the excitation point h s1 Depth from the start of the current layer to the first vertical element h r1 Calculate the vertical propagation path of the reflected wave through each layer. s si ,in i = 1 ,2…… N , N This represents the number of layers the reflected wave passes through. Step S302: Calculate the vertical travel time of the reflected wave in each layer. in i = 1 ,2…… N , N This represents the number of layers the reflected wave passes through. Step S303: Calculate the vertical incidence time from the first excitation point to the depth of the first vertical element. t 0sr : ； Step S304: Calculate the root mean square velocity from the first excitation point to the depth of the first vertical element. v sr : ； Step S305: Take the first receiving point ( x g1 , h g1 From the depth of the first excitation point in step S301 h s1 Depth from the layer to the first receiving point h g1 Calculate the vertical propagation path of the reflected wave through each layer. s gi ,in i = 1 ,2…… N, N This represents the number of layers the reflected wave passes through. Step S306: Calculate the vertical travel time for each layer. ,in i = 1 ,2…… N, N This represents the number of layers the reflected wave passes through. Step S307: Calculate the vertical incidence time from the first excitation point to the depth of the first receiver point. t 0sg : ； Step 308: Calculate the root mean square velocity at the depth from the first excitation point to the first receiver point. v sg : ； Step S309: Calculate the first excitation point ( x s1 , h s1 ) to the first receiving point ( x gn , h gn The location of the multiple reflection point at the depth of the first vertical element. ; in, x s and x g These represent the x-coordinates of the excitation point and the receiver point, respectively. Step S310: Locate the multiple reflection point x r Mapped to surface mesh ( b xk , b h1 ), and increment the coverage count by 1, where k=x r / dx .

2. The method for calculating the number of wave coverages based on layered media according to claim 1, characterized in that, In step S4, the positions of multiple wave reflection points at each surface depth of a shot receiver are calculated and mapped to the surface mesh. Specific operations include: Following steps S301 to S310, traverse the depths of all vertical surface element meshes and calculate the first excitation point. x s1 , h s1 ) to the first receiving point ( x g1 , h g1 Map the positions at all vertical facet mesh depths and update the corresponding coverage counts.

3. The method for calculating the number of wave coverages based on layered media according to claim 2, characterized in that, In step S5, the positions of multiple wave reflection points for each shot receiver at each layer are calculated and mapped to a surface mesh. Specific operations include: Repeat steps S3 and S4 to traverse all excitation and receiver positions, calculate the surface mapping positions from all excitation points to all receiver points at all surface depths, and update the coverage count. The final updated coverage count is the obtained multi-wave coverage count.

4. The method for calculating the number of wave coverages based on layered media according to claim 3, characterized in that, The method further includes step S6, outputting the coverage count profile, specifically: The surface mesh mapped in step S5 ( b xk , b hl In ) b xk The horizontal x-coordinate is the x-coordinate. b hl The vertical coordinate h is the ordinate, and the graph is plotted, with the color intensity representing the number of times the position is covered.

5. A system for calculating the number of wave coverages based on layered media, characterized in that, The system is used to perform the steps in the method for calculating the number of wave coverages based on layered media according to any one of claims 1-4, the system comprising: The input module is used to input parameters; Create a module for creating coverage count statistics cell meshes; The first calculation module is used to calculate the position of the multiple wave reflection point of a shot receiver at a depth of one surface element and map it to the surface element mesh. The second calculation module is used to calculate the position of the multiple wave reflection point of a shot receiver at each surface depth and map it to the surface mesh. The third calculation module is used to calculate the location of multiple wave reflection points for each shot receiver at each layer and map them to a surface mesh.

6. A computer-readable medium, characterized in that, The computer-readable storage medium stores at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the method for calculating the number of wave coverages based on a layered medium as described in any one of claims 1-4.

7. A computer device, characterized in that, It includes a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method for calculating the number of wave coverages based on a layered medium as described in any one of claims 1-4.

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