A method, device and medium for designing an imaging grid of a seismic three-dimensional observation system

Abstract

The application provides a seismic three-dimensional observation system imaging grid design method, which comprises the following steps: obtaining geological conditions of an exploration work area, and determining a main frequency and a propagation speed of a seismic wavelet according to the geological conditions; calculating a first parameter according to the main frequency of the seismic wavelet, and calculating a grid size of seismic imaging according to the propagation speed and the first parameter. The application also provides a computer device and a computer readable storage medium. The application is based on the wavelength relationship between the P wave and the S wave of the seismic wavelet in different speed strata, uses the sampling theorem to ensure the non-aliasing sampling of the seismic prestack migration, ensures the requirement of the imaging grid for the migration imaging in the acquisition observation system design stage, and further ensures the imaging precision of the seismic exploration.

Description

Technical Field

[0001] This invention belongs to the field of geological exploration, and specifically relates to a method, equipment and medium for designing an imaging grid for a three-dimensional seismic observation system. Background Technology

[0002] In seismic exploration, seismic data acquisition typically originates from seismic detectors. The use of wired detectors necessitates the concept of detector lines, where the distance between detector points on each line cannot be too large or too small, severely restricting the spatial distribution of these points on the surface. With the widespread deployment of nodal wireless instruments, the constraints of detector lines will be completely broken, enabling new acquisition and observation system design methods. This requires designing and deploying uniformly random shot-detector points adapted to the distribution of terrain features. This necessitates the layout of the imaging grid. Traditionally, the imaging grid is considered a pixel grid, but with the advent of wave equation migration and reverse time migration, pixel grids and imaging grids can not be completely identical. To ensure imaging accuracy and reduce seismic data acquisition costs, a reasonable imaging grid needs to be designed, which in turn leads to a reasonable shot-detector point distribution. Traditional pixel sizes are designed based on single-frequency waves, but there is no necessary connection between the frequency of a single-frequency wave and the dominant frequency of a seismic wavelet, making it difficult to intuitively represent the necessary relationship between seismic resolution and imaging grid size.

[0003] Therefore, an effective solution is needed to address the above problems. Summary of the Invention

[0004] To address the above problems, this invention proposes an imaging grid design method for a three-dimensional seismic observation system, comprising:

[0005] Obtain the geological conditions of the exploration area, and determine the dominant frequency and propagation velocity of the seismic wavelet based on the geological conditions;

[0006] The first parameter is calculated based on the dominant frequency of the seismic wavelet, and the grid size of the seismic imaging is calculated based on the propagation velocity and the first parameter.

[0007] In some embodiments of the present invention, calculating the first parameter based on the dominant frequency of the seismic wavelet includes:

[0008] The amplitude value of the seismic wavelet is calculated iteratively using the dominant frequency of the seismic wavelet in a predetermined time increment, and it is determined whether the absolute value of the amplitude value of the seismic wavelet is less than a predetermined threshold.

[0009] In response to the absolute value of the amplitude of the seismic wavelet being less than a predetermined threshold, the time increment is used as the first parameter.

[0010] In some embodiments of the present invention, the formula for iteratively calculating the amplitude value of the seismic wavelet using its dominant frequency in predetermined time increments includes calculating the amplitude value of the seismic wavelet using the following formula:

[0011] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t);

[0012] Where Amp is the amplitude of the seismic wavelet, fpeak is the dominant frequency of the seismic wavelet, t is the time increment for each iteration, and EXP represents the exponential operation with the natural constant e as the base.

[0013] In some embodiments of the present invention, calculating the grid size of the seismic image based on the propagation velocity and the first parameter includes:

[0014] The second parameter is calculated based on the first parameter and the propagation velocity of the seismic wavelet.

[0015] In some embodiments of the present invention, calculating the second parameter based on the first parameter and the propagation velocity of the seismic wavelet includes calculating the second parameter using the following formula:

[0016] D = t * 2.0 * V * W;

[0017] Where D represents the second parameter, t is the first parameter, V represents the propagation velocity of the seismic wavelet in the exploration area, and W represents the weight of the seismic wavelet in the exploration area.

[0018] In some embodiments of the present invention, the method further includes:

[0019] The weights are calculated based on the ratio of the transverse wave velocity to the longitudinal wave velocity of the seismic wavelet.

[0020] In some embodiments of the present invention, the method further includes:

[0021] The weight is calculated based on the ratio of the shear wave velocity to the p-wave velocity of the seismic wavelet in the exploration area.

[0022] In some embodiments of the present invention, calculating the grid size of the seismic image based on the propagation velocity and the first parameter further includes:

[0023] Determine the optimal number of sampling points within a seismic wavelength of the exploration area, divide the second parameter by the number of sampling points, and use the result as the grid size of the seismic imaging.

[0024] Another aspect of the present invention provides a computer device comprising:

[0025] At least one processor; and

[0026] A memory storing computer instructions executable on the processor, which, when executed by the processor, implement the steps of any of the methods described in the above embodiments.

[0027] In another aspect of the present invention, a computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of any of the methods described in the above embodiments.

[0028] This invention is based on the wavelength relationship between P-waves and S-waves in strata with different velocities of seismic wavelets, and uses the sampling theorem to ensure that there is no spurious frequency sampling in pre-stack seismic migration. This ensures that the requirements for the imaging grid of migration imaging are met during the design stage of the acquisition and observation system, thereby ensuring the imaging accuracy of seismic exploration. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0030] Figure 1 This is a flowchart of a method for designing an imaging grid for a three-dimensional seismic observation system, as proposed in an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of a computer device according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of a computer storage medium proposed in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0034] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0035] like Figure 1As shown, this invention proposes an imaging grid design method for a three-dimensional seismic observation system, which includes:

[0036] Step S1: Obtain the geological conditions of the exploration area, and determine the dominant frequency and propagation speed of the seismic wavelet based on the geological conditions;

[0037] Step S2: Calculate the first parameter based on the dominant frequency of the seismic wavelet, and calculate the grid size of the seismic imaging based on the propagation velocity and the first parameter.

[0038] In this embodiment, in step S1, based on the geological conditions of the exploration area, the propagation velocity and dominant frequency of the selected seismic wavelet under those geological conditions are queried. Specifically, the dominant frequency fpeak and propagation velocity of different seismic wavelets under those geological conditions can be obtained based on the geological conditions of the exploration area where the project is being carried out, and according to existing experience or technical manuals.

[0039] In step S2, the grid size for mounting the seismic imaging is calculated based on the dominant frequency and propagation velocity of the seismic wavelet used.

[0040] In some embodiments of the present invention, calculating the first parameter based on the dominant frequency of the seismic wavelet includes:

[0041] The amplitude value of the seismic wavelet is calculated iteratively using the dominant frequency of the seismic wavelet in a predetermined time increment, and it is determined whether the absolute value of the amplitude value of the seismic wavelet is less than a predetermined threshold.

[0042] In response to the absolute value of the amplitude of the seismic wavelet being less than a predetermined threshold, the time increment is used as the first parameter.

[0043] In some embodiments of the present invention, the formula for iteratively calculating the amplitude value of the seismic wavelet using its dominant frequency in predetermined time increments includes calculating the amplitude value of the seismic wavelet using the following formula:

[0044] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t);

[0045] Where Amp is the amplitude of the seismic wavelet, fpeak is the dominant frequency of the seismic wavelet, t is the time increment for each iteration, and EXP represents the exponential operation with the natural constant e as the base.

[0046] In this embodiment, the time t satisfying the above formula is first calculated using the dominant frequency of the seismic wavelet. In each iteration, the value of t is incremented by one standard unit, i.e., dt = 0.001 seconds, and t = k * dt is calculated. The value of t is then incremented by 1, i.e., k = k + 1. In this embodiment, when the absolute value of Amp is less than a predetermined threshold of 1.0 * 10... -7 If the condition is met, then the current t is taken as the first parameter.

[0047] Specifically, assuming that the geological task of seismic exploration in the exploration area is to protect the dominant frequency of seismic waves with fpeak = 30Hz, and the minimum layer velocity at the main target layer is V = 3000.0 m / s.

[0048] Let dt = 0.001 seconds, k = 0;

[0049] Round 1 iteration

[0050] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0051] =(1.0-19.7392*30*30*0*0)*EXP(-9.8696*30*30*0*0)=1.0

[0052] Increment k by 1, i.e., k = 1;

[0053] Because |Amp|=1.0>1.0*10 -7 Therefore, the execution continues.

[0054] Second iteration

[0055] Calculate: t = k * dt = 0.001.

[0056] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0057] =(1.0-19.7392*30*30*0.001*0.001)*EXP(-9.8696*30*30*0.001*0.001)=0.99973354

[0058] Increment k by 1, i.e., k = 2

[0059] Because |Amp|=0.99973354>1.0*10 -7 Therefore, the execution continues.

[0060] Third iteration

[0061] ...

[0062] 49th iteration

[0063] Calculate: t = k * dt = 0.048

[0064] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0065] =(1.0-19.7392*30*30*0.048*0.048)*EXP(-9.8696*30*30*0.048*0.048)=-5.16667*10-8

[0066] Because |Amp| = 5.16667 * 10 -8 <1.0*10 -7 The iterative calculation terminates. The current t = 0.048 is used as the value of the first parameter.

[0067] It should be noted that, in this embodiment, the predetermined threshold adopted by the present invention is 1.0*10. -7 You can also set a larger or smaller preset threshold as needed, for example, 1.0*10. -5 Or 1.0*10 -8 The specific settings can be freely configured based on the accuracy of the measurement task.

[0068] In some embodiments of the present invention, calculating the grid size of the seismic image based on the propagation velocity and the first parameter includes:

[0069] The second parameter is calculated based on the first parameter and the propagation velocity of the seismic wavelet.

[0070] In some embodiments of the present invention, calculating the second parameter based on the first parameter and the propagation velocity of the seismic wavelet includes calculating the second parameter using the following formula:

[0071] D = t * 2.0 * V * W;

[0072] Where D represents the second parameter, t is the first parameter, V represents the propagation velocity of the seismic wavelet in the exploration area, and W represents the weight of the seismic wavelet in the exploration area.

[0073] In this embodiment, the second parameter D is calculated using the propagation velocity of the seismic wavelet and the aforementioned first parameter. Specifically, D is calculated according to the formula above, based on the value of the first parameter t calculated in the above embodiment. If shear wave or converted wave exploration is selected, the weight W = 0.5774; if P-wave exploration is selected, the weight is 1. Specifically, taking a value of 0.048 seconds in the above embodiment as an example, V = 3000 m / s, then...

[0074] The expression is: D = t * 2.0 * V * W

[0075] =0.048 * 2.0 * 3000.0 * 0.5774

[0076] =166.2912

[0077] The value of the second parameter D is 166.2912.

[0078] In some embodiments of the present invention, the method further includes:

[0079] The weights are calculated based on the ratio of the transverse wave velocity to the longitudinal wave velocity of the seismic wavelet.

[0080] In this embodiment, the weight W in the above formula is calculated as the ratio of the shear wave velocity to the p-wave velocity of the seismic wavelet. The weight can be based on the ratio of the shear wave velocity to the p-wave velocity of the seismic wavelet under the given geological conditions. As mentioned earlier, W = 0.5774 is the typical ratio of the shear wave velocity to the p-wave velocity of a seismic wavelet.

[0081] In some embodiments of the present invention, the method further includes:

[0082] The weight is calculated based on the ratio of the shear wave velocity to the p-wave velocity of the seismic wavelet in the exploration area.

[0083] In this embodiment, in order to adapt to different geological conditions or when the geological conditions of the exploration area are more complex, the shear wave velocity and longitudinal wave velocity of the seismic wavelet in the current exploration area can be obtained by pre-measurement.

[0084] In some embodiments of the present invention, calculating the grid size of the seismic image based on the propagation velocity and the first parameter further includes:

[0085] Determine the optimal number of sampling points within a seismic wavelength of the exploration area, divide the second parameter by the number of sampling points, and use the result as the grid size of the seismic imaging.

[0086] In this embodiment, after obtaining the second parameter D through the above calculation, an appropriate number of sampling points is selected based on conditions such as the construction cost of the exploration task. After determining the number of sampling points, the distance between imaging points, i.e. the grid size, is calculated by dividing the second parameter D by the number of sampling points.

[0087] Specifically, the selection of the number of sampling points per seismic wavelength in exploration projects typically needs to consider both construction costs and detection accuracy. A preferred number of sampling points is 16, resulting in a grid size of:

[0088] Dx=Dy=D / 16.0=166.2912 / 16.0

[0089] = 10.3932 meters;

[0090] To minimize rounding errors in seismic processing, the grid size here should be less than 10.3932 meters; it can be rounded to 10 meters. Dx and Dy above represent the distances between imaging points in two directions on the horizontal plane.

[0091] In some embodiments of the present invention, the grid size is also used in a three-dimensional grid, i.e., Dx = Dy = Dz, where Dz represents the distance between imaging points in the vertical direction.

[0092] The present invention is illustrated below with specific embodiments:

[0093] In this embodiment, the detection method of longitudinal wave is used. According to the above weight generation formula, W = the ratio of the longitudinal wave velocity to the longitudinal wave velocity, that is, W = 1.

[0094] Based on the conditions of the above embodiment, let dt = 0.001 seconds and the calculation unit k = 0. Calculate t = k * dt, perform iterative calculations, and use the predetermined threshold of 1.0 * 10^6 seconds. -7 The process is as follows:

[0095] Round 1 iteration

[0096] Calculate: t = k * dt = 0.0.

[0097] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0098] =(1.0-19.7392*30*30*0*0)*EXP(-9.8696*30*30*0*0)=1.0

[0099] Increment k by 1, i.e., k = 1

[0100] Because |Amp|=1.0>1.0*10-7 Therefore, the execution continues.

[0101] Second iteration

[0102] Calculate: t = k * dt = 0.001.

[0103] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0104] =(1.0-19.7392*30*30*0.001*0.001)*EXP(-9.8696*30*30*0.001*0.001)=0.99973354

[0105] Increment k by 1, i.e., k = 2

[0106] Because |Amp|=0.99973354>1.0*10 -7 Therefore, the execution continues.

[0107] Third iteration

[0108] ...

[0109] 49th iteration

[0110] Calculate: t = k * dt = 0.048

[0111] Amp=(1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t)

[0112] =(1.0-19.7392*30*30*0.048*0.048)*EXP(-9.8696*30*30*0.048*0.048)=-5.16667*10-8

[0113] Because |Amp| = 5.16667 * 10 -8 <1.0*10 -7 Then t = 0.048;

[0114] Further calculate the second parameter D: D = t * 2.0 * V * W = 0.048 * 2 * 3000 = 288;

[0115] After obtaining the second parameter D, the number of sampling points is also set to 16, so the grid size is 288 / 16 = 18 meters. Therefore, when using P-wave exploration, the spacing between imaging points can be set to 18 meters.

[0116] Another aspect of the present invention provides a computer device comprising:

[0117] At least one processor; and

[0118] A memory storing computer instructions executable on the processor, which, when executed by the processor, implement the steps of any of the methods described in the above embodiments.

[0119] Another aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of any of the methods described in the above embodiments.

[0120] This invention is based on the wavelength relationship between P-waves and S-waves in strata with different velocities of seismic wavelets, and uses the sampling theorem to ensure that there is no spurious frequency sampling in pre-stack seismic migration. This ensures that the requirements for the imaging grid of migration imaging are met during the design stage of the acquisition and observation system, thereby ensuring the imaging accuracy of seismic exploration.

[0121] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0122] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0123] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0124] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0125] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for designing an imaging grid for a three-dimensional seismic observation system, characterized in that, include: Obtain the geological conditions of the exploration area, and determine the dominant frequency and propagation velocity of the seismic wavelet based on the geological conditions; The first parameter is calculated based on the dominant frequency of the seismic wavelet, and the grid size of the seismic imaging is calculated based on the propagation velocity and the first parameter. The calculation of the first parameter based on the dominant frequency of the seismic wavelet includes: The amplitude value of the seismic wavelet is calculated iteratively using the dominant frequency of the seismic wavelet in a predetermined time increment, and it is determined whether the absolute value of the amplitude value of the seismic wavelet is less than a predetermined threshold. In response to the absolute value of the amplitude of the seismic wavelet being less than a predetermined threshold, the time increment is used as the first parameter. The step of calculating the grid size of the seismic image based on the propagation velocity and the first parameter includes: The second parameter is calculated based on the first parameter and the propagation velocity of the seismic wavelet; Determine the optimal number of sampling points within a seismic wavelength of the exploration area, divide the second parameter by the number of sampling points, and use the result as the grid size of the seismic imaging.

2. The method according to claim 1, characterized in that, The step of iteratively calculating the amplitude value of the seismic wavelet using its dominant frequency in predetermined time increments includes calculating the amplitude value of the seismic wavelet using the following formula: Amp = (1.0-19.7392*fpeak*fpeak*t*t)*EXP(-9.8696*fpeak*fpeak*t*t); Where Amp is the amplitude of the seismic wavelet, fpeak is the dominant frequency of the seismic wavelet, t is the time increment for each iteration, and EXP represents the exponential operation with the natural constant e as the base.

3. The method according to claim 1, characterized in that, The calculation of the second parameter based on the first parameter and the propagation velocity of the seismic wavelet includes calculating the second parameter using the following formula: D = t * 2.0 * V * W; Where D represents the second parameter, t is the first parameter, V represents the propagation velocity of the seismic wavelet in the exploration area, and W represents the weight of the seismic wavelet in the exploration area.

4. The method according to claim 3, characterized in that, Also includes: The weights are calculated based on the ratio of the transverse wave velocity to the longitudinal wave velocity of the seismic wavelet.

5. The method according to claim 3, characterized in that, Also includes: The weight is calculated based on the ratio of the shear wave velocity to the p-wave velocity of the seismic wavelet in the exploration area.

6. A computer device, characterized in that, include: At least one processor; as well as A memory storing computer instructions executable on the processor, which, when executed by the processor, implement the steps of the method according to any one of claims 1-5.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-5.

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