Method and system for calculating multiple coverage times based on layered medium

Abstract

The invention provides a stratified medium-based multiple wave coverage number calculation method and system, and belongs to the field of in-well seismic exploration. The method comprises the following steps: S1, inputting parameters; s2, creating a coverage frequency statistical surface element grid; s3, calculating the position of a multiple reflection point of one shot point at one surface element depth, and mapping the position to the surface element grid; s4, calculating the position of a multiple reflection point of a shot point at each surface element depth, and mapping the position to the surface element grid; and S5, calculating the position of a multiple reflection point of each shot point in each layer, and mapping the position to the surface element grid. The method disclosed by the invention has the advantages of high calculation efficiency and relatively high calculation precision, and has innovativeness and practicability in VSP acquisition design in a well.

Description

Technical Field

[0001] The invention belongs to the field of borehole seismic exploration, and in particular relates to a method and system for calculating the number of multiple wave coverages based on layered media. Background Art

[0002] Vertical seismic profiling (VSP) has the characteristics of high signal-to-noise ratio and high resolution due to its reception in the well, and its first-order multiple waves on the surface have the advantages of wide ray path and large imaging range, so it has special applications in the field of seismic exploration. For example, through the interference of VSP direct waves and surface first-order multiple waves, the multiple wave records can be reconstructed into ground-like seismic records for imaging, thereby expanding the imaging range of VSP and performing fine imaging of special structures near the well.

[0003] The acquisition design in VSP multiple wave exploration is the premise to ensure the exploration effect, and the calculation of the multiple wave coverage is the key step in the acquisition design. At present, there is no method specifically for calculating the coverage of VSP multiple waves in practical applications. Therefore, finding a method to calculate the coverage of VSP multiple waves is an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and to provide a method and system for calculating the number of multiple wave coverage based on layered media, while taking into account both calculation efficiency and accuracy.

[0005] The present invention is achieved through the following technical solutions:

[0006] A first aspect of the present invention provides a method for calculating the number of multiple wave coverages based on a layered medium, comprising the following steps:

[0007] Step S1, input parameters;

[0008] Step S2, creating a coverage frequency statistical bin grid;

[0009] Step S3, calculating the position of the multiple wave reflection point of a shot check point at a bin depth, and mapping it to the bin grid;

[0010] Step S4, calculating the position of the multiple wave reflection point of a shot check point at each bin depth, and mapping it to the bin grid;

[0011] Step S5: Calculate the position of the multiple wave reflection point of each shot check point in each layer and map it to the bin grid.

[0012] A further improvement of the present invention is:

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

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

[0015] Enter the positions of all excitation points involved in the calculation (x sm ,h sm ), where m = 1, 2...M; receiving point position (x gn ,h gn ), where n = 1, 2...N; M and N are the number of excitation points and receiving points respectively; x represents the coordinate in the horizontal direction, and h represents the coordinate in the depth direction;

[0016] Input bin grid spacing d x and d h ; where d x ,d h Represent the horizontal width and vertical height of the panel grid respectively.

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

[0018] The step S2 creates a coverage frequency statistics bin grid, and the specific operations include:

[0019] Calculate the horizontal extent x of the bin grid max =x sM -x g1 , vertical range h max =h I -h1; where x g1 Indicates the x-coordinate of the first detection point, x sM represents the x-coordinate of the last excitation point, where h I is the depth of the last layer of the model, and h1 is the depth of the first layer of the model;

[0020] Calculate the number of horizontal surface element grids K = x max / d x , and the number of vertical surface elements L = h max / d h ;

[0021] Set the horizontal extent of the bin grid to x max Divide into K equal facets and number them b xk , k = 1, 2 ... K; the vertical range of the surface element grid h max Divide into L equal facets and number them b hl , l=1,2……L;

[0022] Each surface element grid (b xk ,bhl )’s initial value of coverage times is set to 0.

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

[0024] In step S3, the position of the multiple wave reflection point of a shot check point at a bin depth is calculated and mapped to the bin grid. The specific operations include:

[0025] Step S301, take the first excitation point (x s1 ,h s1 ), from the excitation point depth h s1 From the layer to the depth h of the first vertical face element r1 The layer where the ray is located, calculate the vertical propagation distance s of each layer si , where i = 1, 2...N, N is the number of layers the ray passes through;

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

[0027] Step S303: Calculate the vertical incident time t from the first excitation point to the first vertical plane depth 0sr :

[0028]

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

[0030]

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

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

[0033] Step S307: Calculate the vertical incident time t from the first excitation point to the first receiving point at depth 0sg :

[0034]

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

[0036]

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

[0038] Among them, x s and x g denote the x-coordinates of the excitation point and the receiving point respectively;

[0039] Step S310: Set the multiple wave reflection point position x r Mapping to the panel grid (b xk ,b h1 ), and add 1 to the number of covers, where k = x r / dx.

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

[0041] In step S4, the position of the multiple reflection point of a shot check point at each bin depth is calculated and mapped to the bin grid. The specific operations include:

[0042] According to steps S301 to S310, all the vertical bin grids are traversed to calculate the first excitation point (x s1 ,h s1 ) to the first receiving point (x g1 ,h g1 ) maps the locations at all vertical bin grid depths and updates the corresponding coverage counts.

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

[0044] In step S5, the multiple reflection point position of each shot check point in each layer is calculated and mapped to the bin grid. The specific operations include:

[0045] Repeat steps S3 and S4 to traverse all excitation points and receiving points, calculate the bin mapping positions from all excitation points to all receiving points at all bin depths, and update the number of coverages;

[0046] The final updated coverage number is the obtained multiple wave coverage number.

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

[0048] The method further comprises step S6, outputting a coverage frequency profile, specifically:

[0049] The surface element grid (b xk ,b hl ) in which b xk The horizontal coordinate x value is the horizontal coordinate, b hl The vertical coordinate h value is the ordinate and is plotted in a graph. The depth of the color represents the number of times the position is covered.

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

[0051] Input module, used to input parameters;

[0052] A creation module is used to create a coverage statistics bin grid;

[0053] The first calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at a bin depth and map it to the bin grid;

[0054] The second calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at each bin depth and map it to the bin grid;

[0055] The third calculation module is used to calculate the position of the multiple wave reflection point of each shot inspection point in each layer and map it to the surface element grid.

[0056] According to a third aspect of the present invention, a computer-readable medium is provided, wherein the computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps in the method for calculating the number of multiple wave coverage based on layered media as described above.

[0057] A fourth aspect of the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for calculating the number of multiple wave coverage based on layered media as described above.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The method of the invention has both fast calculation efficiency and high calculation accuracy, and is innovative and practical in the design of VSP acquisition in wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The present invention provides a flowchart of a method for calculating the number of multiple wave coverage based on layered media;

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

[0062] Figure 3 is the profile of the number of multiple wave coverage;

[0063] Figure 4 This is the multiple wave ray path diagram when the bin grid depth is 7420 meters;

[0064] Figure 5 is the number of multiple wave coverage of each bin when the bin grid depth is 7420 meters;

[0065] Figure 6 This is the multiple wave ray path diagram when the bin grid depth is 8110 meters;

[0066] Figure 7 It is the number of multiple wave coverage of each bin when the bin grid depth is 8110 meters. DETAILED DESCRIPTION

[0067] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0068] [Example 1]

[0069] The embodiment of the present invention provides a method for calculating the number of multiple wave coverage based on layered media, such as Figure 1 and Figure 2 As shown, the specific steps include:

[0070] Step S1, input parameters;

[0071] Specifically include:

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

[0073] Enter the positions of all excitation points involved in the calculation (x sm ,h sm ), where m = 1, 2...M; receiving point position (x gn ,h gn ), where n = 1, 2...N; M and N are the number of excitation points and receiving points respectively; x represents the coordinate in the horizontal direction, and h represents the coordinate in the depth direction;

[0074] Input bin grid spacing d x and d h ; where d x ,d h Represent the horizontal width and vertical height of the panel grid respectively.

[0075] Step S2, creating a coverage frequency statistical bin grid;

[0076] Specific operations include:

[0077] Calculate the horizontal extent x of the bin grid max =x sM -x g1 , vertical range h max =h I -h1; where x g1 Indicates the x-coordinate of the first detection point, x sM represents the x-coordinate of the Mth (last) excitation point, where h I is the depth of the last layer of the model, and h1 is the depth of the first layer of the model;

[0078] Calculate the number of horizontal surface element grids K = x max / d x , and the number of vertical surface elements L = h max / d h ;

[0079] Set the horizontal extent of the bin grid to x max Divide into K equal facets and number them b xk , k = 1, 2 ... K; the vertical range of the surface element grid h max Divide into L equal facets and number them b hl , l=1,2……L;

[0080] Each surface element grid (b xk ,b hl )’s initial value of coverage times is set to 0.

[0081] Step S3, calculating the position of the multiple wave reflection point of a shot check point at a bin depth, and mapping it to the bin grid;

[0082] Specific operations include:

[0083] Step S301, take the first excitation point (x s1 ,h s1 ), from the excitation point depth h s1 From the layer to the depth h of the first vertical face element r1 The layer where the ray is located, calculate the vertical propagation distance s of each layer si , where i = 1, 2...N, N is the number of layers the ray passes through;

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

[0085] Step S303: Calculate the vertical incident time t from the first excitation point to the first vertical plane depth 0sr :

[0086]

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

[0088]

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

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

[0091] Step S307: Calculate the vertical incident time t from the first excitation point to the first receiving point at depth 0sg :

[0092]

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

[0094]

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

[0096] Among them, xs and x g denote the x-coordinates of the excitation point and the receiving point respectively;

[0097] Step S310: Set the multiple wave reflection point position x r Mapping to the panel grid (b xk ,b h1 ), and add 1 to the number of covers, where k = x r / dx.

[0098] Step S4, calculating the position of the multiple wave reflection point of a shot check point at each bin depth, and mapping it to the bin grid;

[0099] Specific operations include:

[0100] According to steps S301 to S310, all the vertical bin grids are traversed to calculate the first excitation point (x s1 ,h s1 ) to the first receiving point (x g1 ,h g1 ) maps the locations at all vertical bin grid depths and updates the corresponding coverage counts.

[0101] Step S5, calculating the position of the multiple wave reflection point of each shot check point in each layer, and mapping it to the bin grid;

[0102] Repeat steps S3 and S4 to traverse all excitation point and receiving point positions, calculate the bin mapping positions from all excitation points to all receiving points at all bin depths, and update the number of coverages.

[0103] The final updated coverage number is the obtained multiple wave coverage number.

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

[0105] Specifically, the result of the calculation step S5 of the third step is plotted into a graph, specifically, the surface element grid (b xk ,b hl ) in which b xk The horizontal coordinate x value is the horizontal coordinate, b hl The vertical coordinate h value is the ordinate and is plotted in a graph. The depth of the color represents the number of times the position is covered.

[0106] Table 1 Example model parameters, 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 P-wave velocity (m / s) 1953 1953 2819 3803 4203 4604 4806 5770 6453 6714 5789

[0109] Figure 3In the embodiment model of Table 1, the surface element grid d x and d h are all 10 meters, and the excitation point depth h s =0, position x s From 0 to 6000 meters (increments of 10 meters), the receiving point position x g = 0, depth h g The profile of the number of covers from 6000 to 7500 meters (increments of 10 meters).

[0110] Figure 4 yes Figure 3 When calculating the coverage times, the output is a ray path diagram with a bin depth of 7440 meters.

[0111] Figure 5 yes Figure 3 Coverage frequency map extracted from the profile when the bin grid depth is 7440 meters.

[0112] Figure 6 yes Figure 3 When calculating the coverage times, the output is a ray path diagram with a bin depth of 8110 meters.

[0113] Figure 7 yes Figure 3 Coverage frequency map extracted from the profile when the bin grid depth is 8110 meters.

[0114] From above Figures 3 to 7 It can be seen from the figure that the multiple wave coverage number profile calculated by the present invention reflects a reasonable multiple wave illumination coverage range, the ray path conforms to the multiple wave propagation law, and the differences in the multiple wave ray paths and coverage numbers at different surface element grid depths can reflect the illumination coverage of the observation system at different target layer depths, indicating that the present method can correctly calculate the multiple wave observation coverage number. In addition, due to the use of the layered medium analytical formula, the calculation in this embodiment only takes 5-8 seconds, indicating that the calculation efficiency of the present invention is very high, and it is practical and effective.

[0115] [Example 2]

[0116] The embodiment of the present invention provides a multiple wave coverage number calculation system based on layered media, comprising:

[0117] Input module, used to input parameters;

[0118] A creation module is used to create a coverage statistics bin grid;

[0119] The first calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at a bin depth and map it to the bin grid;

[0120] The second calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at each bin depth and map it to the bin grid;

[0121] The third calculation module is used to calculate the position of the multiple wave reflection point of each shot inspection point in each layer and map it to the surface element grid.

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

[0123] [Example 3]

[0124] An embodiment of the present invention provides a computer-readable storage medium storing at least one computer-executable program. When the at least one program is executed by the computer, the computer executes the steps in the method for calculating the number of multiple wave coverage based on layered media as described above.

[0125] [Example 4]

[0126] An embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps in the method for calculating the number of multiple wave coverage based on layered media as described above.

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

[0128] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A method for calculating the number of multiple wave coverage based on layered media, characterized in that: The following steps are involved: Step S1, input parameters; Step S2, creating a coverage frequency statistical bin grid; Step S3, calculating the position of the multiple wave reflection point of a shot check point at a bin depth, and mapping it to the bin grid; Step S4, calculating the position of the multiple wave reflection point of a shot check point at each bin depth, and mapping it to the bin grid; Step S5: Calculate the position of the multiple wave reflection point of each shot check point in each layer and map it to the bin grid.

2. The method for calculating the multiple wave coverage times based on layered media according to claim 1, characterized in that: The input parameters in step S1 specifically include: Input model parameters (h i ,v i ), i = 1, 2...I, I is the number of model layers, h i represents the layer depth of the reflected wave in layer i, v i represents the layer velocity of the reflected wave in layer i; Enter the positions of all excitation points involved in the calculation (x sm ,h sm ), where m = 1, 2...M; receiving point position (x gn ,h gn ), where n = 1, 2...N; M and N are the number of excitation points and receiving points respectively; x represents the coordinate in the horizontal direction, and h represents the coordinate in the depth direction; Input bin grid spacing d x and d h ; where d x ,d h Represent the horizontal width and vertical height of the panel grid respectively.

3. The method for calculating the multiple wave coverage times based on layered media according to claim 2, characterized in that: The step S2 creates a coverage frequency statistics bin grid, and the specific operations include: Calculate the horizontal extent x of the bin grid max =x sM -x g1 , vertical range h max =h I -h1; where x g1 Indicates the x-coordinate of the first detection point, x sM represents the x-coordinate of the last excitation point, where h I is the depth of the last layer of the model, and h1 is the depth of the first layer of the model; Calculate the number of horizontal surface element grids K = x max / d x , and the number of vertical surface elements L = h max / d h ; Set the horizontal extent of the bin grid to x max Divide into K equal facets and number them b xk , k = 1, 2 ... K; the vertical range of the surface element grid h max Divide into L equal facets and number them b hl , l=1,2……L; Each surface element grid (b xk ,b hl )’s initial value of coverage times is set to 0.

4. The method for calculating the multiple wave coverage times based on layered media according to claim 3, characterized in that: In step S3, the position of the multiple wave reflection point of a shot check point at a bin depth is calculated and mapped to the bin grid. The specific operations include: Step S301, take the first excitation point (x s1 ,h s1 ), from the excitation point depth h s1 From the layer to the depth h of the first vertical face element r1 The layer where the ray is located, calculate the vertical propagation distance s of each layer si , where i = 1, 2...N, N is the number of layers the ray passes through; Step S302: Calculate the vertical travel time t of the seismic wave in each layer layer by layer si =s si / v i Where i = 1, 2...N, N is the number of layers the ray passes through; Step S303: Calculate the vertical incident time t from the first excitation point to the first vertical plane depth 0sr : Step S304: Calculate the root mean square velocity v from the first excitation point to the first vertical plane element depth sr : Step S305: Take the first receiving point (x g1 ,h g1 ), from the first excitation point depth h in step S301 s1 The depth from the layer to the first receiving point is h g1 The layer where the ray is located, calculate the vertical propagation distance s of each layer gi , where i = 1, 2...N, N is the number of layers the ray passes through; Step S306: Calculate the vertical travel time of each layer layer by layer Where i = 1, 2...N, N is the number of layers the ray passes through; Step S307: Calculate the vertical incident time t from the first excitation point to the first receiving point at depth 0sg : Step 308: Calculate the root mean square velocity v at the depth from the first excitation point to the first receiving point sg : Step S309: Calculate the first excitation point (x s1 ,h s1 ) to the first receiving point (x gn ,h gn ) is the location of the multiple reflection point at the first vertical bin depth Among them, x s and x g denote the x-coordinates of the excitation point and the receiving point respectively; Step S310: Set the multiple wave reflection point position x r Mapping to the panel grid (b xk ,b h1 ), and add 1 to the number of covers, where k = x r / dx.

5. The method for calculating the multiple wave coverage times based on layered media according to claim 4, characterized in that: In step S4, the position of the multiple reflection point of a shot check point at each bin depth is calculated and mapped to the bin grid. The specific operations include: According to steps S301 to S310, all the vertical bin grids are traversed to calculate the first excitation point (x s1 ,h s1 ) to the first receiving point (x g1 ,h g1 ) maps the locations at all vertical bin grid depths and updates the corresponding coverage counts.

6. The method for calculating the multiple wave coverage times based on layered media according to claim 5, characterized in that: In step S5, the multiple reflection point position of each shot check point in each layer is calculated and mapped to the bin grid. The specific operations include: Repeat steps S3 and S4 to traverse all excitation points and receiving points, calculate the bin mapping positions from all excitation points to all receiving points at all bin depths, and update the number of coverages; The final updated coverage number is the obtained multiple wave coverage number.

7. The method for calculating the multiple wave coverage times based on layered media according to claim 6, characterized in that: The method further comprises step S6, outputting a coverage frequency profile, specifically: The surface element grid (b xk ,b hl ) in which b xk The horizontal coordinate x value is the horizontal coordinate, b hl The vertical coordinate h value is the ordinate and is plotted in a graph. The depth of the color represents the number of times the position is covered.

8. A multiple wave coverage number calculation system based on layered media, characterized in that: include: Input module, used to input parameters; Creation module, used to create coverage frequency statistical bin grid; The first calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at a bin depth and map it to the bin grid; The second calculation module is used to calculate the position of the multiple wave reflection point of a shot inspection point at each bin depth and map it to the bin grid; The third calculation module is used to calculate the position of the multiple wave reflection point of each shot inspection point in each layer and map it to the surface element grid.

9. A computer-readable medium, characterized in that The computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps of the method for calculating the multiple wave coverage number based on the layered medium according to any one of claims 1 to 7.

10. A computer device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for calculating the multiple wave coverage times based on layered media according to any one of claims 1 to 7.

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