OVT domain arbitrary anisotropic medium five-dimensional p-wave travel time calculation method and device

Abstract

The present application relates to the technical field of petroleum geophysical exploration, and discloses a method and device for calculating five-dimensional P-wave travel time of anisotropic medium in OVT domain, which comprises the following steps: setting a global coordinate system of stratum and establishing an orthogonal observation system, determining a migration distance vector slice domain, wherein the migration distance vector slice domain contains a plurality of migration distance vector slices, each vector slice corresponds to a migration distance and an azimuth angle; dividing the migration distance vector slice domain in polar coordinate system according to the migration angle and azimuth angle of each migration distance vector slice to obtain a five-dimensional observation system; calculating the reflection wave travel time of each migration distance vector slice according to the migration distance and azimuth angle of each migration distance vector slice; extracting a migration distance vector slice gather; and performing normal moveout correction on the reflection wave travel time of each migration distance vector slice domain in the migration distance vector slice gather to obtain a corrected reflection wave travel time. The present application takes into account the information of azimuth angle and migration distance in the process of travel time calculation, and therefore has important reference value in wide-azimuth seismic interpretation.

Description

Technical Field

[0001] This invention relates to the field of petroleum geophysical exploration technology, specifically to a method and apparatus for calculating the five-dimensional P-wave travel time of an arbitrary anisotropic medium in the OVT domain. Background Technology

[0002] For oil and gas exploration, with increasingly complex geological targets, the requirements for seismic exploration are constantly rising, and wide-azimuth seismic exploration has become one of the mainstream technological development directions. Compared with narrow-azimuth seismic exploration, wide-azimuth seismic exploration provides wider illumination, a more complete seismic wavefield, and higher signal-to-noise ratio, resolution, and fidelity. Therefore, it has significant advantages in identifying faults, fractures, stratigraphic lithology and fluids, and in steep-dip imaging. Currently, wide-azimuth seismic exploration is widely used in complex steep structures, carbonate fracture-cavity formations, lithological oil and gas reservoir imaging, and fracture prediction.

[0003] With the widespread adoption of wide-azimuth seismic exploration, wide-azimuth seismic data processing techniques, represented by offset vector tile (OVT) processing, have also developed rapidly. The main characteristic of these techniques is that they establish and process five-dimensional seismic gathers containing both offset and azimuth information on a per-trace basis. Because wide-azimuth seismic data possesses richer azimuth information, wide-azimuth seismic interpretation techniques often focus on anisotropy analysis. By analyzing the azimuthal differences in seismic properties such as travel time, velocity, amplitude, and frequency of seismic waves, the anisotropic properties of reservoirs are identified.

[0004] The azimuth anisotropy of strata, according to their symmetry from simple to complex, can be classified into media with horizontal transverse isotropy (HTI), orthorhombic anisotropy, monoclinic, and triclinic anisotropy. Triclinic anisotropy, lacking both a symmetry plane and axis, represents the most complex case of anisotropy and can also be termed arbitrary anisotropy. Research on the seismic wave properties of arbitrary anisotropy media is currently limited to theoretical studies, such as approximations and inversions of travel times within simple observation systems; its application in practical processing remains largely unexplored. Summary of the Invention

[0005] In view of this, the present invention provides a method and apparatus for calculating the five-dimensional P-wave travel time of arbitrary anisotropic media in the OVT domain, so as to solve the problem of lack of travel time calculation for seismic waves in arbitrary anisotropic media in the prior art.

[0006] In a first aspect, the present invention provides a method for calculating the five-dimensional P-wave travel time of an arbitrary anisotropic medium in the OVT domain. The method includes: setting a global coordinate system for the formation and establishing a cross-shaped orthogonal observation system; determining an offset vector patch within the orthogonal observation system, the offset vector patch containing multiple offset vector patches, each corresponding to an offset and an azimuth angle; dividing the offset vector patch in a polar coordinate system according to the offset angle and azimuth angle of each offset vector patch to obtain a five-dimensional observation system; calculating the reflected wave travel time of each offset vector patch within the offset vector patch in the five-dimensional observation system based on the offset angle and azimuth angle of each offset vector patch; extracting offset vector patch gathers; and performing normal time difference correction on the reflected wave travel time of each offset vector patch in the offset vector patch gathers to obtain the corrected reflected wave travel time.

[0007] The five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain provided in this invention solves the problem of travel time processing for complex anisotropic media in wide-azimuth seismic exploration. The travel time calculation takes into account information such as azimuth and offset, thus having significant reference value in wide-azimuth seismic interpretation. Simultaneously, the normal time difference correction technique can distinguish between time differences caused by offset and azimuth while ensuring accuracy, laying the foundation for subsequent anisotropic parameter inversion. Geophysical data processing personnel can calculate OVT gathers for complex anisotropic media under a five-dimensional observation system according to this invention, and can also develop anisotropic parameter inversion methods based on the method provided in this invention.

[0008] In one optional implementation, the travel time of reflected waves of each offset vector piece in the offset vector piece domain is calculated based on the offset angle and azimuth angle of each offset vector piece, including: calculating the anisotropy parameters of the medium based on the density normalization coefficient matrix of the formation medium and a preset P-wave phase velocity; calculating the layer thickness normalized offset distance of each offset vector piece based on the offset distance of each offset vector piece and the depth of the horizontal reflecting surface; calculating the zero offset two-way travel time of each offset vector piece based on the depth of the horizontal reflecting surface and the preset P-wave phase velocity; and calculating the travel time of reflected waves of each offset vector piece in the offset vector piece domain based on the zero offset two-way travel time, the layer thickness normalized offset distance of each offset vector piece, the azimuth angle of each offset vector piece, and the anisotropy parameters.

[0009] In one optional implementation, the travel time of reflected waves from each offset vector sheet in the offset vector sheet gather is corrected for normal time difference to obtain the corrected travel time of reflected waves. This includes: determining the reference azimuth of each offset vector sheet; calculating the first travel time of each offset vector sheet based on the layer thickness normalized offset and the reference azimuth; calculating the second travel time of each offset vector sheet when the layer thickness normalized offset is 0 based on the reference azimuth of each OVT body; calculating the correction amount of each offset vector sheet based on the difference between the first and second travel times; and calculating the corrected travel time of reflected waves from each offset vector sheet based on the difference between the travel time of reflected waves and the correction amount.

[0010] In one alternative implementation, the anisotropy parameters of the medium are calculated using the following formula:

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020] Among them, A ij This represents the elements in the density-normalized stiffness coefficient matrix, where α is the preset P-wave phase velocity, and ε... x , ε y , ε z These represent the differences between the P-wave phase velocity and α in the medium along the coordinate axes x1, x2, and x3, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions in the plane (x1, x2), respectively.

[0021] In one alternative implementation, the layer thickness-normalized offset of the offset vector patch is calculated using the following formula:

[0022]

[0023] in, denoted as the normalized offset distance for layer thickness, x is the offset distance of the offset distance vector patch, and H is the depth of the horizontal reflective surface.

[0024] In one alternative implementation, the zero-offset two-way travel time is calculated using the following formula:

[0025]

[0026] Where T0 is the zero-offset two-way travel time, H is the depth of the horizontal reflecting surface, and α is the preset P-wave phase velocity.

[0027] In one alternative implementation, the travel time of the reflected wave of the offset vector sheet is calculated using the following formula:

[0028]

[0029] Where T0 is the zero-offset two-way travel time, The offset distance is the normalized offset distance for the layer thickness of the offset distance vector slice. For P-wave azimuth anisotropy velocity factors:

[0030]

[0031] ε x , ε y , ε z These represent the differences between the P-wave phase velocity and the preset P-wave phase velocity α in the x1, x2, and x3 directions of the medium, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions in the plane (x1, x2), respectively. This represents the azimuth angle of the offset vector slice.

[0032] Secondly, this invention provides a five-dimensional P-wave travel time calculation device for an arbitrary anisotropic medium in the OVT domain. The device includes: an orthogonal observation system establishment module, used to set the global coordinate system of the formation and establish a cross-shaped orthogonal observation system, defining an offset vector patch domain within the orthogonal observation system, the offset vector patch domain containing multiple offset vector patches, each corresponding to an offset distance and an azimuth angle; a five-dimensional observation system establishment module, used to divide the offset vector patch domain in a polar coordinate system according to the offset angle and azimuth angle of each offset vector patch to obtain a five-dimensional observation system; a reflected wave travel time calculation module, used to calculate the reflected wave travel time of each offset vector patch in the offset vector patch domain within the five-dimensional observation system, based on the offset distance and azimuth angle of each offset vector patch; a gather extraction module, used to extract offset vector patch gathers; and a reflected wave travel time correction module, used to perform normal time difference correction on the reflected wave travel time of each offset vector patch in the offset vector patch gathers to obtain corrected reflected wave travel times.

[0033] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the method for calculating the five-dimensional P-wave travel time of an arbitrary anisotropic medium in the OVT domain as described in the first aspect or any corresponding embodiment.

[0034] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the five-dimensional P-wave travel time calculation method for an arbitrary anisotropic medium in the OVT domain according to the first aspect above or any corresponding embodiment. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating the method for calculating the five-dimensional P-wave travel time of an arbitrary anisotropic medium in the OVT domain according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of a cross arrangement according to an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of an OVT sheet according to an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of OVT data grouping rules in the Cartesian coordinate system according to an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of OVT data grouping rules in polar coordinates according to an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of a five-dimensional observation system according to an embodiment of the present invention;

[0042] Figure 7 This is a five-dimensional travel time diagram of the reflected P-wave OVT domain of Model 1 according to an embodiment of the present invention;

[0043] Figure 8 This is a five-dimensional travel time percentage error diagram of the reflected P-wave OVT domain of Model 1 according to an embodiment of the present invention;

[0044] Figure 9 This is a diagram showing the five-dimensional travel time normal time difference correction result of Model 1 reflected P-wave OVT domain according to an embodiment of the present invention;

[0045] Figure 10 This is a five-dimensional travel time diagram of the reflected P-wave OVT domain according to an embodiment of the present invention;

[0046] Figure 11 This is a five-dimensional travel time percentage error diagram of the reflected P-wave OVT domain according to an embodiment of the present invention;

[0047] Figure 12 This is a diagram showing the five-dimensional travel time normal time difference correction result of the reflected P-wave OVT domain according to an embodiment of the present invention;

[0048] Figure 13 This is a five-dimensional travel time diagram of the reflected P-wave OVT domain of Model 3 according to an embodiment of the present invention;

[0049] Figure 14 This is a five-dimensional travel time percentage error diagram of the reflected P-wave OVT domain of Model 3 according to an embodiment of the present invention;

[0050] Figure 15 This is a diagram showing the five-dimensional travel time normal time difference correction result of the reflected P-wave OVT domain according to an embodiment of the present invention;

[0051] Figure 16 This is a structural block diagram of a five-dimensional P-wave travel time calculation device for an arbitrary anisotropic medium in the OVT domain according to an embodiment of the present invention;

[0052] Figure 17 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Example 1:

[0055] According to an embodiment of the present invention, a method for calculating the travel time of a five-dimensional P-wave in an arbitrary anisotropic medium in the OVT domain is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0056] This embodiment provides a method for calculating the five-dimensional P-wave travel time in an arbitrary anisotropic medium in the OVT domain. Figure 1 This is a flowchart of a five-dimensional P-wave travel time calculation method for an arbitrary anisotropic medium in the OVT domain according to an embodiment of the present invention, as shown below. Figure 1 As shown, the process includes the following steps:

[0057] Step S101: Set the global coordinate system of the strata and establish an orthogonal observation system arranged in a cross shape. In the orthogonal observation system, determine the offset vector patch domain. The offset vector patch domain contains multiple offset vector patches (OVT patches), and each vector patch corresponds to an offset and an azimuth angle.

[0058] In an alternative embodiment, a Cartesian coordinate system is assumed as the global coordinate system, with its x3 axis being vertical and its x1 and x2 axes being horizontal and orthogonal to each other; the background medium is a uniform stratum, and the horizontal reflective surface at the bottom of the stratum is parallel to the (x1, x2) plane.

[0059] like Figure 2 As shown, in the cross-shaped orthogonal observation system, the detector lines are distributed in parallel along the x1 direction, and the source points are excited sequentially according to the shot lines distributed along the x2 axis. The combination of a shot line and a detector line is a cross subset in the cross arrangement.

[0060] In a single cross subset, seismic traces whose center points of the shot and receiver fall within a fixed range can be combined into an OVT sheet. Each OVT sheet represents the offset and azimuth within a certain range. An OVT sheet is like... Figure 3As shown, identical OVT patches in different cross subsets form OVT domains. Each OVT domain is a single-coverage profile within the work area, and a single OVT patch represents a specific location within the OVT domain.

[0061] Step S102: Divide the offset vector patch domain in polar coordinates according to the offset angle and azimuth angle of each offset vector patch to obtain a five-dimensional observation system.

[0062] When grouping the OVT domain, the data is arranged in Cartesian coordinates as follows: Figure 4 As shown. In Figure 4 In the OVT domain grouping process shown, grouping is only performed according to the x and y coordinates within the three-dimensional coordinate system. Therefore, the offset and azimuth changes of the OVT domain are not uniform. Thus, in this embodiment of the invention, considering the offset and azimuth changes of the OVT domain, the OVT domain should be divided in a polar coordinate system. The grouping rules for dividing the OVT domain in the polar coordinate system are as follows: Figure 5 As shown.

[0063] After dividing the OVT domain in polar coordinates, the resulting five-dimensional observation system is as follows: Figure 6 As shown, Figure 6 The triangle symbol in the image represents the position of the OVT plate. Each OVT plate has its corresponding source, which is located in a position that is centrally symmetrical with respect to the detector.

[0064] Step S103: In the five-dimensional observation system, the travel time of the reflected wave of each offset vector piece in the offset vector piece domain is calculated based on the offset distance and azimuth angle of each offset vector piece.

[0065] Step S104: Extract the offset distance vector slice set.

[0066] In an alternative embodiment, the OVT gather is obtained by arranging the azimuth-offset order.

[0067] Step S105: Perform normal time difference correction on the travel time of the reflected waves of each offset vector slice in the offset vector slice collection to obtain the corrected travel time of the reflected waves.

[0068] The five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain provided in this invention solves the problem of travel time processing for complex anisotropic media in wide-azimuth seismic exploration. The travel time calculation takes into account information such as azimuth and offset, thus having significant reference value in wide-azimuth seismic interpretation. Simultaneously, the normal time difference correction technique can distinguish between time differences caused by offset and azimuth while ensuring accuracy, laying the foundation for subsequent anisotropic parameter inversion. Geophysical data processing personnel can calculate OVT gathers for complex anisotropic media under a five-dimensional observation system according to this invention, and can also develop anisotropic parameter inversion methods based on the method provided in this invention.

[0069] Example 2:

[0070] In an embodiment of the invention, in a five-dimensional observation system, the travel time of the reflected wave of each offset vector piece in the offset vector piece domain is calculated based on the offset distance and azimuth angle of each offset vector piece, specifically including:

[0071] Step a1: Calculate the anisotropy parameters of the medium based on the density normalization coefficient matrix of the formation medium and the preset P-wave phase velocity.

[0072] In an optional embodiment, the anisotropy parameters of the medium include the difference between the P-wave phase velocity and α in the coordinate axes x1, x2, x3, where α is a preset P-wave phase velocity, which can be, for example, the P-wave phase velocity in a reference isotropic medium; the gradient of the P-wave velocity variation in the coordinate axes x1, x2, x3; the degree of P-wave deviation from the axial direction in the plane (x1, x2); and the degree of deviation of the P-wave direction from the fast and slow S-wave directions in the plane (x1, x2).

[0073] In an optional embodiment, the anisotropy parameters of the medium are calculated using the following formula:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Among them, A ij This represents the elements in the density-normalized stiffness coefficient matrix, where α is the preset P-wave phase velocity, and ε... x , ε y , ε z These represent the differences between the P-wave phase velocity and α in the medium along the coordinate axes x1, x2, and x3, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions within the plane (x1, x2). An S-wave is a wave whose vibration direction is perpendicular to its propagation direction. When an S-wave propagates along the interface between two media, the vibration direction of the fast transverse wave is parallel to the interface, while the vibration direction of the slow transverse wave is perpendicular to the interface. In this embodiment of the invention, the interface is not involved; the P-wave is a longitudinal wave propagating and vibrating along the x3 axis, and ξ... 16 ξ 26 These represent the degree of deviation between the P-wave direction of the longitudinal wave propagating and vibrating along the Z-axis and the S-wave direction of the longitudinal wave propagating along the Z-axis and vibrating along the x1 and x2 axes, respectively.

[0084] Step a2: Calculate the layer thickness normalized offset distance of each offset vector piece based on the offset distance of each offset vector piece and the depth of the horizontal reflective surface.

[0085] In an optional embodiment, the layer thickness normalized offset of the OVT sheet is calculated using the following formula:

[0086]

[0087] Where x is the layer thickness normalized offset, x is the offset of the offset vector patch, and H is the depth of the horizontal reflection surface (coinciding with the symmetry plane of the formation).

[0088] Step a3: Calculate the zero-offset two-way travel time of each offset vector piece based on the depth of the horizontal reflector and the preset P-wave phase velocity.

[0089] In an alternative embodiment, the zero-offset two-way travel time is calculated using the following formula:

[0090]

[0091] Where T0 is the zero-offset two-way travel time, H is the depth of the horizontal reflecting surface, and α is the preset P-wave phase velocity.

[0092] Step a4: Calculate the travel time of the reflected wave of each offset vector sheet based on the zero offset two-way travel time, the layer thickness normalized offset of each offset vector sheet, the azimuth angle of each offset vector sheet, and the anisotropy parameters.

[0093] In an optional embodiment, the travel time of the reflected wave of the offset vector sheet is calculated using the following formula:

[0094]

[0095] Where T0 is the zero-offset two-way travel time, The offset distance is the normalized offset distance for the layer thickness of the offset distance vector slice. For P-wave azimuth anisotropy velocity factors:

[0096]

[0097] ε x , ε y , ε z These represent the differences between the P-wave phase velocity and the preset P-wave phase velocity α in the x1, x2, and x3 directions of the medium, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions in the plane (x1, x2), respectively. This represents the azimuth angle of the offset vector slice.

[0098] In some optional implementations, step S105 specifically includes:

[0099] Step b1: Determine the reference orientation of each offset vector piece.

[0100] Step b2: Calculate the first travel time of each offset vector slice based on the normalized offset distance of the layer thickness and the reference azimuth.

[0101] Step b3: Calculate the second travel time of each offset vector piece when the layer thickness normalized offset is 0, based on the reference azimuth of each offset vector piece.

[0102] In this embodiment of the invention, the calculation formulas for the first travel time and the second travel time are incorporated into the above-mentioned calculation formula for the travel time of the reflected wave.

[0103] Step b4: Calculate the correction amount for each offset vector piece based on the difference between the first and second travel times of each offset vector piece.

[0104] Step b5: Calculate the corrected reflected wave travel time of each offset vector piece based on the difference between the reflected wave travel time and the correction amount.

[0105] For example, if the x1 direction is determined as the reference azimuth during the normal time difference correction process, i.e. In terms of direction:

[0106] The first travel time of the i-th VOT slice, calculated based on the normalized offset of the layer thickness and the reference azimuth, is:

[0107] The second travel time of the i-th VOT slice is T(0,0) when the normalized offset of the layer thickness is 0, calculated based on the reference azimuth of the i-th VOT slice.

[0108] The correction amount for the i-th VOT segment, calculated based on the difference between the first and second travel times, is:

[0109] The corrected reflected wave travel time of the i-th VOT sheet, calculated based on the difference between the reflected wave travel time and the correction amount, is as follows:

[0110] The method of correcting the travel time of reflected waves in this embodiment of the invention can eliminate the bending of the in-phase axis caused by the increase of the offset distance, laying the foundation for analyzing the orientation anisotropy of the medium.

[0111] In one specific embodiment, the five-dimensional P-wave travel time calculation method for OVT domain arbitrary anisotropic media provided in the above embodiments was used to calculate the travel time in a tilted transverse isotropic medium, which has one axis of symmetry. Table 1 shows the medium model parameters used in the numerical verification process of this embodiment. The model contains a set of 6×6 stiffness coefficient matrices, which are symmetrical along the diagonal elements; therefore, only the upper triangular matrix is ​​shown.

[0112] Table 1

[0113]

[0114] Table 2 shows the reference velocity α0 selected in this embodiment and the anisotropic parameters calculated according to the stiffness coefficient matrix provided in Table 1 and the anisotropic parameter calculation formula provided in the above embodiment.

[0115] Table 2

[0116]

[0117] Figure 7In the diagram, the light-colored solid line represents the precise timekeeping calculated using the ANRAY software package, and the dark-colored dashed line represents the timekeeping calculated using the method described in this invention. Figure 8 The value in the middle represents the percentage error between the accurate timekeeping and the timekeeping calculated by the method provided in the above embodiments. According to... Figure 8 It can be seen that the timing error calculated by the present invention is within 5%, which meets the production requirements. Figure 9 The paper demonstrates the OVT domain travel time after normal time difference correction according to the method provided by the present invention. The azimuth travel time changes periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0118] In one specific embodiment, the five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain provided in the above embodiments was used to calculate the travel time in an orthogonal anisotropic medium, which has two symmetry planes. Table 3 shows the medium model parameters used in the numerical verification process of this invention. The model contains a set of 6×6 stiffness coefficient matrices, which are symmetric along the diagonal elements; therefore, only the upper triangular matrix is ​​shown.

[0119] Table 3

[0120]

[0121] Table 4 shows the reference velocity α0 selected in this embodiment and the anisotropic parameters calculated according to the stiffness coefficient matrix provided in Table 1 and the anisotropic parameter calculation formula provided in the above embodiment.

[0122] Table 4

[0123]

[0124] Figure 10 In the diagram, the light-colored solid line represents the precise timekeeping calculated using the ANRAY software package, and the dark-colored dashed line represents the timekeeping calculated using the method described in this invention. Figure 11 The value in the middle represents the percentage error between the accurate timekeeping and the timekeeping calculated by the method provided in the above embodiments. According to... Figure 11 It can be seen that the timing error calculated by the present invention is within 5%, which meets the production requirements. Figure 12 The paper demonstrates the OVT domain travel time after normal time difference correction according to the method provided by the present invention. The azimuth travel time changes periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0125] In one specific embodiment, the five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain provided in the above embodiments was used to calculate the travel time in a triclinic anisotropic medium. The triclinic anisotropic medium has three non-orthogonal symmetry planes, and all elements in the stiffness coefficient matrix of the triclinic anisotropic medium are non-zero, thus representing the most complex anisotropic case. Table 5 shows the medium model parameters used in the numerical verification process of this invention. This model contains a set of 6×6 stiffness coefficient matrices, which are symmetrical along their diagonal elements; therefore, only the upper triangular matrix is ​​shown.

[0126] Table 5

[0127]

[0128] Table 6 shows the reference velocity α0 selected in this embodiment and the anisotropic parameters calculated according to the stiffness coefficient matrix provided in Table 1 and formula (1).

[0129] Table 6

[0130]

[0131] Figure 13 In the diagram, the light-colored solid line represents the precise timekeeping calculated using the ANRAY software package, and the dark-colored dashed line represents the timekeeping calculated using the method described in this invention. Figure 14 The value in the middle represents the percentage error between the accurate timekeeping and the timekeeping calculated by the method provided in the above embodiments. According to... Figure 14 It can be seen that the timing error calculated by the present invention is within 5%, which meets the production requirements. Figure 15 The paper demonstrates the OVT domain travel time after normal time difference correction according to the method provided by the present invention. The azimuth travel time changes periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0132] Example 3:

[0133] This embodiment also provides a five-dimensional P-wave travel time calculation device for an arbitrary anisotropic medium in the OVT domain. This device is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0134] This embodiment provides a five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in the OVT domain, such as... Figure 16 As shown, it includes:

[0135] The orthogonal observation system establishment module 161 is used to set the global coordinate system of the strata and establish a cross-shaped orthogonal observation system. In the orthogonal observation system, the offset vector patch is determined. The offset vector patch contains multiple offset vector patches, and each vector patch corresponds to an offset and an azimuth angle.

[0136] The five-dimensional observation system establishment module 162 is used to divide the offset vector patch domain in polar coordinates according to the offset angle and azimuth angle of each offset vector patch to obtain the five-dimensional observation system.

[0137] The reflected wave travel time calculation module 163 is used to calculate the reflected wave travel time of each offset vector piece in the offset vector piece domain based on the offset distance and azimuth angle of each offset vector piece in the five-dimensional observation system.

[0138] The gather extraction module 164 is used to extract offset vector slice gathers.

[0139] The reflected wave travel time correction module 165 is used to perform normal time difference correction on the reflected wave travel time of each offset vector slice in the offset vector slice collection to obtain the corrected reflected wave travel time.

[0140] In some optional implementations, the reflected wave travel time calculation module 163 specifically includes:

[0141] The anisotropy parameter calculation unit is used to calculate the anisotropy parameters of the formation medium based on the density normalization coefficient matrix and the preset P-wave phase velocity.

[0142] The layer thickness normalized offset calculation unit is used to calculate the layer thickness normalized offset of each offset vector piece based on the offset distance of each offset vector piece and the depth of the horizontal reflective surface.

[0143] The zero-offset two-way travel time calculation unit is used to calculate the zero-offset two-way travel time of each offset vector piece based on the depth of the horizontal reflector and the preset P-wave phase velocity.

[0144] The reflected wave travel time calculation unit is used to calculate the reflected wave travel time of each offset vector sheet in the offset vector sheet domain based on the zero offset two-way travel time, the layer thickness normalized offset of each offset vector sheet, the azimuth angle of each offset vector sheet, and the anisotropy parameters.

[0145] In some optional implementations, the reflected wave travel time correction module 165 specifically includes:

[0146] The reference orientation determination unit is used to determine the reference orientation of each offset vector piece.

[0147] The first travel time calculation unit is used to calculate the first travel time of each offset vector slice based on the layer thickness normalized offset and the reference azimuth angle.

[0148] The second travel time calculation unit is used to calculate the second travel time of each offset vector slice when the layer thickness normalized offset is 0, based on the reference azimuth of each OVT body.

[0149] The correction calculation unit is used to calculate the correction amount of each offset vector piece based on the difference between the first and second travel times of each offset vector piece.

[0150] The reflected wave travel time correction unit is used to calculate the corrected reflected wave travel time of each offset vector piece based on the difference between the reflected wave travel time and the correction amount of each offset vector piece.

[0151] In some alternative implementations, the anisotropy parameters of the medium are calculated using the following formula:

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161] Among them, A ij This represents the elements in the density-normalized stiffness coefficient matrix, where α is the preset P-wave phase velocity, and ε... x , ε y , ε z These represent the differences between the P-wave phase velocity and α in the medium along the coordinate axes x1, x2, and x3, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions in the plane (x1, x2), respectively.

[0162] In some alternative implementations, the layer thickness-normalized offset of the offset vector patch is calculated using the following formula:

[0163]

[0164] in, denoted as the normalized offset distance for layer thickness, x is the offset distance of the offset distance vector patch, and H is the depth of the horizontal reflective surface.

[0165] In some alternative implementations, the zero-offset two-way travel time is calculated using the following formula:

[0166]

[0167] Where T0 is the zero-offset two-way travel time, H is the depth of the horizontal reflecting surface, and α is the preset P-wave phase velocity.

[0168] In some alternative implementations, the travel time of the reflected wave of the offset vector sheet is calculated using the following formula:

[0169]

[0170] Where T0 is the zero-offset two-way travel time, The offset distance is the normalized offset distance for the layer thickness of the offset distance vector patch domain. For P-wave azimuth anisotropy velocity factors:

[0171]

[0172] ε x , ε y , ε z These represent the differences between the P-wave phase velocity and the preset P-wave phase velocity α in the x1, x2, and x3 directions of the medium, respectively; η x η y η z These represent the gradients of the P-wave velocity in the medium along the x1, x2, and x3 axes, respectively; χ z ξ represents the degree to which the P-wave deviates from the axis within the plane (x1,x2); 16 ξ 26 These represent the degree of deviation between the P-wave direction and the fast and slow S-wave directions in the plane (x1, x2), respectively. This represents the azimuth angle of the offset vector slice.

[0173] In this embodiment, the five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in the OVT domain is presented in the form of a functional unit. Here, a unit refers to an ASIC circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0174] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0175] This invention also provides a computer device having the above-described features. Figure 16 The device shown is a five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in the OVT domain.

[0176] Please see Figure 17 , Figure 17 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 17 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 17 Take a processor 10 as an example.

[0177] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0178] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0179] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0180] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0181] The computer device also includes an input device 30 and an output device 40. The processor 10, memory 20, input device 30, and output device 40 can be connected via a bus or other means. Figure 17 Taking the example of a connection between China and Israel via a bus.

[0182] Input device 30 can receive input numerical or character information, and generate key signal inputs related to user settings and function control of the computer device, such as a touchscreen, keypad, mouse, trackpad, touchpad, joystick, one or more mouse buttons, trackball, joystick, etc. Output device 40 may include display devices, auxiliary lighting devices (e.g., LEDs), and haptic feedback devices (e.g., vibration motors). The aforementioned display devices include, but are not limited to, liquid crystal displays, light-emitting diodes, displays, and plasma displays. In some alternative embodiments, the display device may be a touchscreen.

[0183] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0184] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for calculating the five-dimensional P-wave travel time in an arbitrary anisotropic medium in the OVT domain, characterized in that, The method includes: A global coordinate system for the strata is established and an orthogonal observation system with a cross arrangement is set up. In the orthogonal observation system, an offset vector patch is determined. The offset vector patch contains multiple offset vector patches, and each vector patch corresponds to an offset and an azimuth angle. The offset vector patch domain is divided in polar coordinates based on the offset angle and azimuth angle of each offset vector patch to obtain a five-dimensional observation system. In the five-dimensional observation system, the travel time of the reflected wave of each offset vector piece in the offset vector piece domain is calculated based on the offset distance and azimuth angle of each offset vector piece. Extract offset vector slice gathers; The travel time of the reflected waves in each offset vector slice of the offset vector slice gather is corrected for normal time difference to obtain the corrected travel time of the reflected waves; The step of performing normal time difference correction on the reflected wave travel time of each offset vector slice in the offset vector slice gather to obtain the corrected reflected wave travel time includes: determining the reference azimuth of each offset vector slice; calculating the first travel time of each offset vector slice based on the layer thickness normalized offset and the reference azimuth angle; calculating the second travel time of each offset vector slice when the layer thickness normalized offset is 0 based on the reference azimuth angle of each OVT body; calculating the correction amount of each offset vector slice based on the difference between the first and second travel times; and calculating the corrected reflected wave travel time of each offset vector slice based on the difference between the reflected wave travel time and the correction amount.

2. The method according to claim 1, characterized in that, The step of calculating the travel time of the reflected wave of each offset vector piece in the offset vector piece domain based on the offset angle and azimuth angle of each offset vector piece includes: The anisotropy parameters of the medium are calculated based on the density normalization coefficient matrix of the formation medium and the preset P-wave phase velocity. The layer thickness normalized offset distance of each offset vector sheet is calculated based on the offset distance of each offset vector sheet and the depth of the horizontal reflective surface. The zero-offset two-way travel time of each offset vector piece is calculated based on the depth of the horizontal reflector and the preset P-wave phase velocity. The travel time of reflected waves in each offset vector sheet in the offset vector sheet domain is calculated based on the zero offset two-way travel time, the layer thickness normalized offset of each offset vector sheet, the azimuth angle of each offset vector sheet, and the anisotropy parameters.

3. The method according to claim 2, characterized in that, The anisotropy parameters of the medium are calculated using the following formula: ， ， ， ， ， ， ， ， ， in, This represents the elements in the density-normalized stiffness coefficient matrix. To preset the P-wave phase velocity, , , These represent the medium on the coordinate axes. , , Directional P-wave phase velocity and Differences; , , These represent the medium on the coordinate axes. , , The gradient of the change in P-wave velocity in the direction; Indicated in a plane , The degree to which the internal P-wave deviates from the axis; , Representing respectively in the plane , The degree of deviation between the direction of the internal P wave and the directions of the fast and slow S waves.

4. The method according to claim 2, characterized in that, The layer thickness normalized offset of the offset vector slice is calculated using the following formula: ， in, The offset is the normalized offset for layer thickness. The offset distance is the offset distance of the offset vector slice. The depth of the horizontal reflective surface.

5. The method according to claim 2, characterized in that, The zero-offset two-way travel time is calculated using the following formula: ， in, For zero offset two-way travel time, The depth of the horizontal reflective surface. The preset P-wave phase velocity.

6. The method according to claim 2, 3, 4, or 5, characterized in that, The travel time of the reflected wave from the offset vector plate is calculated using the following formula: ， in, For zero offset two-way travel time, The offset distance is the normalized offset distance for the layer thickness of the offset distance vector slice. For P-wave azimuth anisotropy velocity factors: , , , These represent the medium on the coordinate axes. , , Directional P-wave phase velocity and preset P-wave phase velocity Differences; , , These represent the medium on the coordinate axes. , , The gradient of the change in P-wave velocity in the direction; Indicated in a plane , The degree to which the internal P-wave deviates from the axis; , Representing respectively in the plane , The degree of deviation between the direction of the internal P wave and the directions of the fast and slow S waves; This represents the azimuth angle of the offset vector slice.

7. A five-dimensional P-wave travel time calculation device for an arbitrary anisotropic medium in the OVT domain, characterized in that, The device includes: The orthogonal observation system establishment module is used to set the global coordinate system of the strata and establish a cross-shaped orthogonal observation system. In the orthogonal observation system, the offset vector patch is determined. The offset vector patch contains multiple offset vector patches, and each vector patch corresponds to an offset and an azimuth angle. The five-dimensional observation system establishment module is used to divide the offset vector patch domain in polar coordinates according to the offset angle and azimuth angle of each offset vector patch to obtain the five-dimensional observation system. The reflected wave travel time calculation module is used to calculate the reflected wave travel time of each offset vector piece in the offset vector piece domain based on the offset distance and azimuth angle of each offset vector piece in the five-dimensional observation system. The gather extraction module is used to extract offset vector slice gathers; The reflected wave travel time correction module is used to perform normal time difference correction on the reflected wave travel time of each offset vector slice in the offset vector slice gather to obtain the corrected reflected wave travel time. The process of performing normal time difference correction on the reflected wave travel time of each offset vector slice in the offset vector slice gather to obtain the corrected reflected wave travel time includes: determining the reference azimuth of each offset vector slice; calculating the first travel time of each offset vector slice based on the layer thickness normalized offset and the reference azimuth; calculating the second travel time of each offset vector slice when the layer thickness normalized offset is 0 based on the reference azimuth of each OVT body; calculating the correction amount of each offset vector slice based on the difference between the first and second travel times; and calculating the corrected reflected wave travel time of each offset vector slice based on the difference between the reflected wave travel time and the correction amount.

8. A computer device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the five-dimensional P-wave travel time calculation method for any one of claims 1 to 6 in the OVT domain.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the five-dimensional P-wave travel time calculation method for any one of claims 1 to 6 in the OVT domain of an arbitrary anisotropic medium.

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