Wide-angle total reflection three-dimensional seismic data acquisition method

Abstract

The invention belongs to the technical field of seismic exploration, and discloses a wide-angle total reflection three-dimensional seismic data acquisition method, which comprises the following steps of: 1, constructing a geologic model of a geologic body of a target stratum; and 2, calculating the total reflection offset according to the geologic model. And a third step of setting the geophone grid size and shot point density of the acquisition system, so that at least the offset lines are uniformly distributed along the circumference by taking the geologic body as the center and the offset is not smaller than the total reflection offset, and setting the number of coverage times according to the amplification factor of the total reflection ratio vertical incidence signal-to-noise ratio. And a fourth step of simulating seismic acquisition of the acquisition system on the geologic model of the target stratum geologic body to obtain wide-angle total reflection three-dimensional seismic data. And a fifth step of adjusting the size of the collection grid and the shot point density until the degree of closeness between the wide-angle total reflection three-dimensional seismic data imaging and the geologic model is higher than a preset threshold value. The acquisition system can acquire wide-angle total reflection seismic signals, improve the seismic signal-to-noise ratio and realize high-definition imaging of a geologic body of a target layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of seismic exploration. More specifically, the present invention relates to a wide-angle total reflection three-dimensional seismic data acquisition method. Background Art

[0002] In seismic exploration by the reflection wave method, to understand the underground structural form, the reflection waves of each interface are continuously traced using an observation system. By separately exciting at many shot points and conducting continuous multiple observations, seismic data is obtained. The observation system consists of a geophone grid and shot points. The selection of the observation system depends on the geological tasks of seismic exploration, the seismic geological conditions of the work area, and the acquisition method used. The general principle is: simple construction, economical and efficient, capable of continuously tracing the underground interface, and meeting the basic requirements for data quality in seismic exploration.

[0003] According to the accuracy requirements in different exploration stages, the layout methods of seismic observation systems are divided into different situations:

[0004] In the regional reconnaissance stage, it is a regional reconnaissance carried out in areas with low exploration levels. The geological task is to understand the distribution of regional geological structures and determine prospective hydrocarbon areas or hydrocarbon-bearing basins. The basis for arranging the observation system is the preliminary data of regional structures derived from geological surveys or geophysical exploration data. It is required to pass through as many structural units as possible under the principle of being perpendicular to the strike of the regional geological structure. The size of the geophone grid is determined according to the scale of the regional geological structure in the work area.

[0005] In the area census stage, the task is to search for possible hydrocarbon accumulation zones in prospective hydrocarbon areas, study the distribution law of strata, and identify larger local structures. The geophone grid is relatively sparse in this stage, and it is usually carried out in the way of two-dimensional seismic exploration.

[0006] In the area detailed survey stage, the main task is to identify the structural characteristics on known structural units, such as distribution range, spatial form, thickness of the target layer, contact relationship between the upper and lower strata, high point position, closure, relationship with adjacent structures, size and distribution of faults, etc., provide the most favorable hydrocarbon-bearing traps, and provide well locations for drilling. In this stage, it is required that the main survey line is perpendicular to the strike of the structure. The survey network of two-dimensional seismic exploration is slightly denser, and three-dimensional seismic exploration can also be directly carried out according to needs.

[0007] In the structural detailed survey and fine measurement stage, the main task is to clarify the specific geological characteristics of hydrocarbon reservoirs on the basis of working on hydrocarbon-bearing traps and provide basic data for reservoir description. This stage is usually mainly carried out by three-dimensional seismic exploration.

[0008] However, in the prior art, even in the stage of detailed structure investigation, since the target is the overall formation, insufficient attention is paid to the imaging of the geological body of the target layer. In a conventional seismic acquisition system, due to the transmission effect of seismic waves, the attenuation of the reflected wave energy will have an adverse impact on the resolution and interpretability of the seismic signal of the target layer. Due to the relatively small azimuth angle, generally less than 30 degrees, the coverage of the seismic reflection signal is low, the "illumination" angle of the seismic signal is relatively narrow, and the reflection of the target layer is blurred.

[0009] In view of this, it is urgently needed in the art to develop a wide-angle total reflection three-dimensional seismic data acquisition method that can provide high-resolution and high-coverage seismic data of the geological body of the target layer. Summary of the Invention

[0010] To solve at least one of the above technical problems, the present invention provides a wide-angle total reflection three-dimensional seismic data acquisition method, including: the first step, constructing a geological model of the geological body of the target layer, and the geological model parameters include: the depth of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of faults in the geological body, the scale of each unit in the geological body, the depth of each unit in the geological body, and the velocity of each unit in the geological body; the second step, calculating the total reflection offset according to the velocity of each unit in the geological body and the depth of each unit in the geological body; the third step, setting the geophone grid size and shot point density of the acquisition system according to the depth of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of faults in the geological body, the scale of each unit in the geological body, and the Fresnel zone interference response radius, so that at least N groups of shot-receiver lines of geophones and shot points are evenly distributed along a circle centered on the geological body and the shot-receiver distance is not less than the total reflection offset, and setting the coverage according to the amplification factor of the total reflection ratio to the vertical incidence signal-to-noise ratio, where N is an integer greater than 6; the fourth step, simulating the seismic acquisition of the geological model of the geological body of the target layer by the acquisition system to obtain wide-angle total reflection three-dimensional seismic data; the fifth step, using the wide-angle total reflection three-dimensional seismic data for imaging and comparing it with the geological model of the geological body of the target layer, and adjusting the acquisition grid size and shot point density until the degree of approximation between the imaging of the wide-angle total reflection three-dimensional seismic data and the geological model of the geological body of the target layer is higher than a preset threshold.

[0011] According to an embodiment of the present invention, calculating the total reflection offset includes: calculating the reflection critical angle of each unit of the geological body according to the velocity of each unit of the geological body and the seismic wave reflection critical angle calculation formula, and taking the maximum reflection critical angle; calculating the offset according to the maximum reflection critical angle and the depth of each unit in the geological body, and selecting the maximum offset among them as the total reflection offset.

[0012] According to an embodiment of the present invention, the Fresnel zone interference response radius, the depth of the top and bottom interfaces of the geological body, and the geometric scale of the geological body are inversely proportional to the grid size; the scale of each unit in the geological body and the density of faults in the geological body are directly proportional to the grid size.

[0013] According to an embodiment of the present invention, the fold formed by the set geophone grid size and shot point density satisfies that the signal-to-noise ratio is more than P times the vertical incidence signal-to-noise ratio, where P is an integer greater than 1; the fold is calculated in the following way: the fold is equal to the number of geophone receiving channels of the acquisition system multiplied by the number of shot point excitations, and then divided by the geophone grid length.

[0014] According to an embodiment of the present invention, in the third step, P takes any value from 7 to 9.

[0015] According to an embodiment of the present invention, in the third step, the included angle of the shot-receiver lines evenly distributed along the circumference with the geological body as the center is 10 to 60 degrees.

[0016] According to an embodiment of the present invention, in the third step, the vertical incidence signal-to-noise ratio includes the maximum value of the signal-to-noise ratio obtained by collecting seismic waves directly above the geological body or in each unit of the geological body.

[0017] According to an embodiment of the present invention, in the fourth step, a three-dimensional wave equation is used to simulate the seismic acquisition of the geological model of the target layer geological body by the acquisition system.

[0018] According to an embodiment of the present invention, in the fourth step, data of geophones and shot points with shot-receiver lines evenly distributed along the circumference with the geological body as the center and shot-receiver offsets not less than the total reflection migration offset are collected to obtain wide-angle total reflection three-dimensional seismic data.

[0019] According to an embodiment of the present invention, in the fifth step, the preset threshold takes any one of 0.7, 0.8, and 0.9.

[0020] In the present invention, the total reflection migration offset is obtained by the critical reflection angle of each unit in the geological body to guide the layout of the acquisition system, so that the acquisition system can collect the total reflection seismic signal for the geological body of the target layer, thereby improving the seismic reflection energy. By setting multiple groups of geophones and shot points with shot-receiver lines evenly distributed along the circumference with the geological body as the center, wide-angle seismic reflection signals can be collected, improving the seismic signal-to-noise ratio and resolution. Using the technical solution of the present invention, three-dimensional seismic high-resolution, high signal-to-noise ratio, and wide-angle fine exploration can be realized, which is helpful for fine seismic carving of oil and gas reservoirs and adjustment of oil and gas reservoir development plans during the oil and gas reservoir development stage.

[0021] The present invention can be applied to extremely shallow layers above 300 meters to solve the problems of engineering seismic exploration in extremely shallow layers above 300 meters and formation shielding in seismic exploration of extremely shallow heavy oil. The present invention can also be applied to shallow layers above 500 meters to solve the problems of formation shielding and low signal-to-noise ratio in oil and gas exploration, and can also be applied to ultra-deep layers below 8000 meters in the deep sea and on land to solve the problems of insufficient reflection energy and low signal-to-noise ratio in seismic exploration. Brief Description of the Drawings

[0022] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understood. In the drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0023] Figure 1 Shows a schematic diagram of a three-dimensional seismic exploration system;

[0024] Figure 2 Shows a schematic diagram of the steps of a wide-angle full-reflection three-dimensional seismic data acquisition method. Detailed Embodiments

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be understood that the terms "comprising" and "including" used in the specification and claims of the present invention indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0027] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification and claims of the present invention, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. It should also be further understood that the term "and / or" used in the specification and claims of the present invention refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] As used in this specification and the claims, the term "if" can be construed contextually as "when" or "once" or "in response to determining" or "in response to detecting". Similarly, the phrase "if determined" or "if [the described condition or event] is detected" can be construed contextually to mean "once determined" or "in response to determining" or "once [the described condition or event] is detected" or "in response to detecting [the described condition or event]".

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] Figure 1 A schematic diagram of a three-dimensional seismic exploration system is shown.

[0031] As Figure 1 shown, in this system 100, a plurality of geophones 110 for detecting seismic waves are arranged at intervals on the surface 101 of the exploration target area, forming a geophone array that covers the target area on a plane. These geophones 110 are connected to the seismic information processing device by wired or wireless means, and a plurality of seismic sources 120 are also provided. The seismic information processing device can perform preliminary processing on seismic data. The working process of the three-dimensional seismic exploration system is as follows: The seismic sources 120 located at multiple positions are artificially excited to generate seismic waves. The seismic waves are reflected from the boundary of the formation 102 and received by the geophone array, forming seismic information collected on a plane and varying with time. The seismic information received by the geophone array represents certain measures of the seismic wave energy as a function of time, such as displacement, velocity, wave impedance, pressure, etc. These information can be grouped in different ways, such as traces, gathers, etc., and then processed or format-converted according to the corresponding relationship of time and space to form a three-dimensional seismic data volume in the form of a three-dimensional array, that is, high-quality three-dimensional seismic fine imaging data is obtained. This three-dimensional seismic data volume is formed by stacking interface points in space. The interpretation of the three-dimensional seismic data volume can observe the morphology of the geological interface from different directions and study the changes of the geological body in three-dimensional space by cutting transverse sections, longitudinal sections, and horizontal slices.

[0032] Figure 2 A schematic diagram of the steps of a wide-angle total reflection three-dimensional seismic data acquisition method is shown.

[0033] As Figure 2As shown in the figure, the present invention provides a wide-angle total reflection three-dimensional seismic data acquisition method 200, including: the first step S201, constructing a geological model of the target layer geological body, where the geological model parameters include: the depths of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of faults in the geological body, the scales of each unit in the geological body, the depths of each unit in the geological body, and the velocities of each unit in the geological body; the second step S202, calculating the total reflection offset according to the velocities of each unit in the geological body and the depths of each unit in the geological body; the third step S203, setting the geophone grid size and shot point density of the acquisition system according to the depths of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of faults in the geological body, the scales of each unit in the geological body, and the Fresnel zone interference response radius, so that at least N groups of shot-receiver lines of geophones and shot points are evenly distributed along the circumference centered on the geological body and the shot-receiver offset is not less than the total reflection offset, and setting the fold according to the amplification factor of the total reflection ratio to the vertical incidence signal-to-noise ratio, where N is an integer greater than 6; the fourth step S204, simulating the seismic acquisition of the geological model of the target layer geological body by the acquisition system to obtain wide-angle total reflection three-dimensional seismic data; the fifth step S205, using the wide-angle total reflection three-dimensional seismic data for imaging and comparing it with the geological model of the target layer geological body, and adjusting the acquisition grid size and shot point density until the degree of approximation between the imaging of the wide-angle total reflection three-dimensional seismic data and the geological model of the target layer geological body is higher than a preset threshold.

[0034] In a certain seismic exploration area, since the setting of its seismic observation system is for the overall stratum and region, the obtained seismic data has a relatively low signal-to-noise ratio with respect to the target layer geological body, and according to the existing seismic data, a clear image of the target layer geological body cannot be obtained. In the present invention, in order to improve the imaging effect of the target layer geological body, the acquisition system for the target layer geological body is redesigned to improve its corresponding noise attenuation and signal energy.

[0035] The geological model of the target layer geological body refers to a model constructed based on the seismic data obtained from the exploration results of the overall stratum and region, which includes: the depths of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of faults in the geological body, the scales of each unit in the geological body, the depths of each unit in the geological body, and the velocities of each unit in the geological body.

[0036] Each unit in the geological body refers to each different component part in the geological body, which has different density, velocity, and depth distribution information. In order to clearly image each unit in the geological body, the total reflection offset is calculated using the velocities of each unit in the geological body and the depths of each unit in the geological body, and the layout of the acquisition system is constrained by the total reflection offset, thereby forming an acquisition system that can provide total reflection seismic data.

[0037] In the second step, the total reflection offset is calculated according to the geological model.

[0038] When calculating the total reflection offset, according to the velocities of each unit in the geological body and the calculation formula of the seismic wave reflection critical angle, calculate the reflection critical angles of each unit in the geological body, and take the maximum reflection critical angle; calculate the offset according to the maximum reflection critical angle and the depths of each unit in the geological body, and select the maximum offset among them as the total reflection offset.

[0039] According to different units in the geological body, multiple reflection critical angles can be calculated respectively. The calculation formula of the seismic wave reflection critical angle is obtained based on Snell's Law. Snell's Law states that when a wave enters a medium with a higher wave velocity from one medium, there is a specific incident angle such that the refracted wave propagates along the interface (i.e., the refraction angle is 90°). The corresponding incident angle at this time is called the critical angle.

[0040] Calculation formula of the seismic wave reflection critical angle:

[0041] θ c =arcsin(v 2 / v 1 )

[0042] θ c : Critical angle (incident angle in the incident medium).

[0043] v 1 : Wave velocity in the incident medium.

[0044] v 2 : Wave velocity in the refracting medium.

[0045] After obtaining multiple reflection critical angles, take the maximum reflection critical angle among them to calculate the offset, and multiple offsets can be obtained. Then select the maximum offset among them again as the constraint for setting the source-receiver offset of the acquisition system, so that the acquisition system can obtain total reflection seismic data. That is, when the source-receiver offset is not less than the total reflection offset, the collected signal is a total reflection signal, and the noise attenuates as the offset increases, so that seismic data with a higher signal-to-noise ratio can be obtained.

[0046] In the third step, according to multiple parameters of the geological body, the grid size of the acquisition system can be set, and the acquisition coverage times can be set according to the requirements of the signal-to-noise ratio. The Fresnel zone interference response radius, the depths of the top and bottom interfaces of the geological body, and the geometric scale of the geological body are inversely proportional to the grid size; the scale of each unit in the geological body and the density of faults in the geological body are directly proportional to the grid size.

[0047] Taking the Fresnel zone interference radius as an example, it restricts the lateral resolution of the acquisition system. The lateral resolution refers to the size of the smallest geological body that can be resolved horizontally by seismic waves, usually represented by the radius of the first Fresnel zone of the reflected wave. From the perspective of physical seismology, it is considered that the resolvable reflected wave received at a certain point on the ground is the result of the superposition of diffracted wavelets within a certain range on the reflection interface. The lateral resolution is the size of this range, which is the first Fresnel zone, that is, the Fresnel zone interference response radius. Geologic bodies larger than this range can theoretically be resolved.

[0048] The radius R of the first Fresnel zone f The calculation formula is as follows:

[0049]

[0050] In the formula, v is the average velocity, t is the two-way reflection time, and f is the main frequency of the seismic wave.

[0051] In the present invention, a further improved technical solution includes arranging part of the shot-receiver lines around the geologic body and evenly distributing them along the circumference with the geologic body as the center, so as to achieve wide-angle acquisition. Wide angle refers to the azimuth angle of seismic acquisition. The acquisition angle of a single shot point is usually about 30 degrees, and the acquisition angle of the present invention can reach 360 degrees. Preferably, the included angle between the shot-receiver lines evenly distributed along the circumference with the geologic body as the center is 5-15 degrees. The greater the circumferential density of the shot-receiver lines evenly distributed along the circumference with the geologic body as the center, the stronger the full reflection signal obtained by the acquisition system and the clearer its imaging. Preferably, N is taken as an integer greater than 10, 20, 30, 100, 200, 300.

[0052] Setting the shot point in the third step is also restricted by the signal-to-noise ratio. That is, the fold number satisfies that the signal-to-noise ratio is more than P times the vertical incidence signal-to-noise ratio, where P is an integer greater than 1. The fold number is calculated by the following method: the fold number is equal to the number of receiver channels of the acquisition system multiplied by the number of shot excitations, and then divided by the receiver grid length.

[0053] During the seismic acquisition process, the noise generated by the shot points exists naturally and is basically unchanged. When the shot-receiver offset increases, the noise will attenuate as the shot-receiver offset increases, and the signal should attenuate equally. However, in the present invention, due to the use of total reflection, the intensity of the signal is enhanced and the attenuation of the signal is alleviated, but the noise attenuation remains unchanged, thereby improving the signal-to-noise ratio. In order to further improve the resolution on the basis of improving the signal-to-noise ratio, the present invention increases the coverage times of the geological body in the target layer. Taking the signal-to-noise ratio of vertical incidence as the standard, when the signal-to-noise ratio of the total reflection signal is greater than P times the signal-to-noise ratio of vertical incidence as the coverage times increase, the requirements for high-definition imaging of the geological body are met. Preferably, P takes any value from 5 to 9. The signal-to-noise ratio of vertical incidence includes the maximum value of the signal-to-noise ratio obtained by collecting seismic waves directly above the geological body or at each unit in the geological body.

[0054] The present invention calculates the total reflection offset of the geological body to constrain the layout of the geophones and shot points, so as to obtain the total reflection seismic signal. By setting multiple groups of shot-receiver lines of geophones and shot points to be evenly distributed along the circumference with the geological body as the center, the purpose of obtaining wide-angle seismic signals is achieved. By constraining the coverage times, the purpose of improving the signal-to-noise ratio is achieved. Through the above three improvements, high-definition imaging of the geological body in the target layer is realized.

[0055] Specifically, when the acquisition system is arranged in the present invention, the geophone grid can be set in a square or circular shape. Among them, there must be some cases where the shot-receiver offset is less than the total reflection offset. Only the settings of some geophones and shot points need to meet the above requirements.

[0056] In the fourth to fifth steps, in order to further optimize the settings of the geophones and shot points in the acquisition system, the three-dimensional wave equation is used to simulate the acquisition of the geological model of the target layer geological body by the acquisition system, and wide-angle total reflection three-dimensional seismic data is obtained and compared with the geological model of the target layer geological body. When the difference between the two is large, the setting parameters of the acquisition grid size and shot point density are adjusted, such as the geophone grid size, shot point position, coverage times, etc., until the imaging of the wide-angle total reflection three-dimensional seismic data is closer to the geological model of the target layer geological body than the preset threshold.

[0057] When calculating the degree of closeness, the geological model parameters can be used as comparison items, and the comparison result is any value from 0 to 1. The closer this value is to 1, the higher the degree of closeness between the two. Preferably, the preset threshold is any one of 0.7, 0.8, and 0.9.

[0058] When collecting wide-angle total reflection three-dimensional seismic data, the objects collected are the data of the geophones and shot points whose shot-receiver lines are evenly distributed along the circumference with the geological body as the center and the shot-receiver offset is not less than the total reflection offset.

[0059] When the degree of approximation between the wide-angle total reflection 3D seismic data and the geological model of the target geological body is higher than a preset threshold, the parameter settings of the acquisition system are completed, and the acquisition system can be used for the actual seismic acquisition of the target geological body.

[0060] In the present invention, the total reflection offset is obtained by the critical reflection angles of each unit in the geological body to guide the layout of the acquisition system, so that the acquisition system can collect total reflection seismic signals for the geological body of the target layer, thereby improving the seismic reflection energy. By setting multiple groups of geophones and shot points with the geological body as the center and evenly distributed along the circumference of the shot-receiver line, wide-angle seismic reflection signals can be collected, improving the seismic signal-to-noise ratio and resolution. Using the technical solution of the present invention, three-dimensional seismic high-resolution, high signal-to-noise ratio, and wide-angle fine exploration can be realized, which is helpful for the fine seismic carving of oil and gas reservoirs and the adjustment of oil and gas reservoir development plans in the oil and gas reservoir development stage.

[0061] The present invention can be applied to extremely shallow layers above 300 meters and shallow layers above 500 meters, solving the problems of extremely shallow engineering seismic problems and formation shielding problems in extremely shallow heavy oil seismic exploration, solving the problems of formation shielding and low signal-to-noise ratio in oil and gas exploration, and can also be applied to ultra-deep layers below 8000 meters in the deep sea and on land, solving the problems of insufficient seismic reflection energy and low signal-to-noise ratio in seismic exploration.

[0062] Although multiple embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many variations, changes, and alternative forms may be contemplated by those skilled in the art without departing from the spirit and scope of the present invention. It should be understood that various alternatives to the embodiments of the present invention described herein may be employed in practicing the present invention. The appended claims are intended to define the scope of the present invention and thus cover equivalents or alternatives within the scope of these claims.

Claims

1. A wide-angle total reflection three-dimensional seismic data acquisition method, characterized in that: include: The first step is to construct a geological model of the target geological body, wherein the geological model parameters include: the depth of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of the faults in the geological body, the scale of each unit in the geological body, the depth of each unit in the geological body, and the velocity of each unit in the geological body; The second step is to calculate the total reflection offset distance according to the velocity of each unit in the geological body and the depth of each unit in the geological body; The third step is to set the detector grid size and shot point density of the acquisition system according to the depth of the top and bottom interfaces of the geological body, the geometric scale of the geological body, the density of the faults in the geological body, the scale of each unit in the geological body, and the Fresnel zone interference response radius, so that there are at least N groups of detectors and shot point shot detection lines uniformly distributed along the circumference with the geological body as the center and the shot distance is not less than the total reflection offset distance, and set the number of coverage times according to the magnification of the vertical incidence signal-to-noise ratio of the total reflection ratio, wherein N is an integer greater than 6; The fourth step is to simulate the seismic acquisition of the geological model of the target geological body by the acquisition system to obtain wide-angle total reflection three-dimensional seismic data; The fifth step is to use the wide-angle total reflection three-dimensional seismic data for imaging and compare it with the geological model of the target geological body, adjust the acquisition grid size and shot point density until the imaging of the wide-angle total reflection three-dimensional seismic data is closer to the geological model of the target geological body than a preset threshold.

2. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: Calculating the total reflection offset distance includes: calculating the reflection critical angle of each unit in the geological body according to the velocity of each unit in the geological body and the calculation formula of the seismic wave reflection critical angle, and taking the maximum reflection critical angle; The offset is calculated according to the maximum reflection critical angle and the depth of each unit in the geological body, and the maximum offset is selected as the total reflection offset.

3. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: The Fresnel zone interference response radius, the depth of the top and bottom interfaces of the geological body, and the geometric scale of the geological body are inversely proportional to the grid size; The scale of each unit in the geological body and the density of faults in the geological body are directly proportional to the grid size.

4. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: The coverage times formed by the set detector grid size and shot point density satisfy the signal-to-noise ratio of more than P times the vertical incidence signal-to-noise ratio, where P is an integer greater than 1; The number of coverages is calculated in the following manner: the number of coverages is equal to the number of detector receiving channels of the acquisition system multiplied by the number of shot point excitations, divided by the length of the detector grid.

5. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 4, characterized in that: In the third step, P takes any value from 7 to 9.

6. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: In the third step, the angle of the shot detection lines uniformly distributed along the circumference with the geological body as the center is 10 to 60 degrees.

7. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: In the third step, the vertical incidence signal-to-noise ratio includes the maximum value of the signal-to-noise ratio obtained by collecting seismic waves from each unit directly above or in the geological body.

8. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: In the fourth step, a three-dimensional wave equation simulation acquisition system is used to perform seismic acquisition of a geological model of the target geological body.

9. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: In the fourth step, data of detectors and shot points evenly distributed along the circumference of the shot detection line with the geological body as the center and the shot distance not less than the total reflection offset distance are collected to obtain wide-angle total reflection three-dimensional seismic data.

10. The wide-angle total reflection three-dimensional seismic data acquisition method according to claim 1, characterized in that: In the fifth step, the preset threshold is any one of 0.7, 0.8, and 0.9.

Images