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

Abstract

The invention relates to the technical field of petroleum geophysical exploration, and discloses a five-dimensional P-wave travel time calculation method and device for any anisotropic medium in an OVT domain, and the method comprises the steps: setting a global coordinate system of a stratum, building an orthogonal observation system, determining an offset vector slice domain which comprises a plurality of offset vector slices, and calculating the five-dimensional P-wave travel time of any anisotropic medium in the OVT domain; each vector sheet corresponds to one offset distance and one azimuth angle; according to the offset angle and the azimuth angle of each offset vector sheet, dividing an offset vector sheet domain in a polar coordinate system to obtain a five-dimensional observation system; calculating the reflected wave travel time of each offset vector sheet according to the offset and the azimuth angle of each offset vector sheet; extracting an offset vector slice gather; and performing normal time difference correction on the reflected wave travel time of each offset vector slice domain in the offset vector slice gather to obtain corrected reflected wave travel time. Information such as the azimuth angle and the offset distance is considered in the travel time calculation process, and therefore the method has important reference value in wide-azimuth seismic interpretation.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum geophysical exploration, and in particular to a method and a device for calculating five-dimensional P-wave travel time of arbitrary anisotropic medium in an OVT domain. Background Art

[0002] For oil and gas exploration, as geological targets become increasingly complex, the requirements for seismic exploration continue to increase, and wide-azimuth seismic exploration has become one of the mainstream technical development directions. Compared with narrow-azimuth seismic exploration, wide-azimuth seismic exploration has a wider acquisition illumination, a more complete seismic wave field, and higher data signal-to-noise ratio, resolution, and fidelity. Therefore, it has great advantages in identifying faults, fractures, stratum lithology and fluids, and steep-angle imaging. At present, wide-azimuth seismic exploration has been widely used in complex high-steep structures, carbonate fractures and caves, lithologic oil and gas reservoir imaging, and fracture prediction.

[0003] With the promotion of wide-azimuth seismic exploration, wide-azimuth seismic data processing technologies represented by offset vector tile (OVT) processing technology have also developed rapidly. The main feature of these technologies is to establish and process five-dimensional seismic gathers containing both offset and azimuth information in units of "slices". Since wide-azimuth seismic data have richer azimuth information, wide-azimuth seismic interpretation technology is often based on anisotropy analysis, which identifies the anisotropic properties of the reservoir by analyzing the azimuth differences of seismic attributes such as travel time, velocity, amplitude, and frequency of seismic waves.

[0004] The azimuthal anisotropy of strata can be divided into horizontal transverse isotropy (HTI) medium, orthogonal anisotropy (OrthorhombicAnisotropy) medium, monoclinic anisotropy (Monoclinic) medium, and triclinic anisotropy (Triclinic) medium according to its symmetry from simple to complex. Triclinic anisotropy medium has no symmetry plane and symmetry axis, representing the most complex case of anisotropy, which can also be called arbitrary anisotropy. The study of seismic wave attributes of arbitrary anisotropic media is currently limited to the theoretical scope, such as the approximation and inversion of its travel time in a simple observation system, and its application in practical processing is still blank. Summary of the invention

[0005] In view of this, the present invention provides a method and device for calculating the travel time of five-dimensional P waves in arbitrary anisotropic media in an 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 the first aspect, the present invention provides a method for calculating the five-dimensional P-wave travel time of an arbitrary anisotropic medium in an OVT domain, the method comprising: setting a global coordinate system of the stratum and establishing a cross-arranged orthogonal observation system, determining an offset vector slice domain in the orthogonal observation system, the offset vector slice domain comprising multiple offset vector slices, each vector slice corresponding to an offset and an azimuth; dividing the offset vector slice domain in a polar coordinate system according to the offset angle and azimuth of each offset vector slice to obtain a five-dimensional observation system; in the five-dimensional observation system, calculating the reflected wave travel time of each offset vector slice in the offset vector slice domain according to the offset and azimuth of each offset vector slice; extracting an offset vector slice track set; performing normal time difference correction on the reflected wave travel time of each offset vector slice in the offset vector slice track set to obtain a corrected reflected wave travel time.

[0007] The method for calculating the five-dimensional P-wave travel time of arbitrary anisotropic media in the OVT domain provided by the embodiment of the present invention solves the problem of travel time processing of complex anisotropic media in wide-azimuth seismic exploration. Information such as azimuth and offset are taken into account in the travel time calculation process, so it has important reference value in wide-azimuth seismic interpretation. At the same time, the normal time difference correction technology can distinguish the time difference caused by offset and azimuth while ensuring accuracy, laying the foundation for subsequent anisotropic parameter inversion. Geophysical data processing personnel can calculate the OVT gathers of complex anisotropic media under the five-dimensional observation system according to the embodiment of the present invention, and can also develop anisotropic parameter inversion methods according to the method provided by the embodiment of the present invention.

[0008] In an optional embodiment, the reflection wave travel time of each offset vector slice in the offset vector slice domain is calculated according to the offset angle and azimuth of each offset vector slice, including: calculating the anisotropy parameters of the medium according to the density normalization coefficient matrix of the formation medium and the preset P-wave phase velocity; calculating the layer thickness normalized offset of each offset vector slice according to the offset of each offset vector slice and the depth of the horizontal reflection surface; calculating the zero-offset two-way travel time of each offset vector slice according to the depth of the horizontal reflection surface and the preset P-wave phase velocity; calculating the reflection wave travel time of each offset vector slice in the offset vector slice domain according to the zero-offset two-way travel time, the layer thickness normalized offset of each offset vector slice, the azimuth of each offset vector slice and the anisotropy parameters.

[0009] In an optional embodiment, a normal time difference correction is performed 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, including: determining the reference azimuth of each offset vector slice; calculating the first travel time of each offset vector slice according to the layer thickness normalized offset and the reference azimuth of each offset vector slice; calculating the second travel time of each offset vector slice when the layer thickness normalized offset is 0 according to the reference azimuth of each OVT body; calculating the correction amount of each offset vector slice according to the difference between the first travel time and the second travel time of each offset vector slice; calculating the corrected reflected wave travel time of each offset vector slice according to the difference between the reflected wave travel time of each offset vector slice and the correction amount.

[0010] In an optional embodiment, the anisotropy parameter of the medium is calculated by the following formula:

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020] Among them, A ij represents the element in the density normalized stiffness coefficient matrix, α is the preset P-wave phase velocity, ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity and α in the direction of coordinate axis x1, x2, and x3; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They respectively represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2).

[0021] In an optional embodiment, the layer thickness normalized offset of the offset vector slice is calculated by the following formula:

[0022]

[0023] in, is the normalized offset of the layer thickness, x is the offset of the offset vector slice, and H is the depth of the horizontal reflection surface.

[0024] In an optional 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 reflection surface, and α is the preset P-wave phase velocity.

[0027] In an optional implementation, the travel time of the reflected wave of the offset vector slice is calculated by the following formula:

[0028]

[0029] Where T0 is the two-way travel time at zero offset, is the normalized offset of the offset vector slice by layer thickness, is the P-wave azimuthal anisotropic velocity factor:

[0030]

[0031] ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity of the medium in the coordinate axis x1, x2, and x3 directions and the preset P-wave phase velocity α; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2); Indicates the azimuth of the offset vector patch.

[0032] In a second aspect, the present invention provides a five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in an OVT domain, the device comprising: an orthogonal observation system establishment module, used to set the global coordinate system of the stratum and establish a cross-arranged orthogonal observation system, in which an offset vector slice domain is determined, wherein the offset vector slice domain includes multiple offset vector slices, and each vector slice corresponds to an offset and an azimuth; a five-dimensional observation system establishment module, used to divide the offset vector slice domain in a polar coordinate system according to the offset angle and azimuth of each offset vector slice, so as to obtain a five-dimensional observation system; a reflection wave travel time calculation module, used to calculate the reflection wave travel time of each offset vector slice in the offset vector slice domain according to the offset and azimuth of each offset vector slice in the five-dimensional observation system; a track collection extraction module, used to extract the offset vector slice track collection; and a reflection wave travel time correction module, used to perform normal time difference correction on the reflection wave travel time of each offset vector slice in the offset vector slice track collection, so as to obtain the corrected reflection wave travel time.

[0033] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the method for calculating five-dimensional P-wave travel time of arbitrary anisotropic medium in the OVT domain of the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0034] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method for calculating five-dimensional P-wave travel time of arbitrary anisotropic media in the OVT domain according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 1 is a flow chart of a method for calculating five-dimensional P-wave travel time in arbitrary anisotropic media in an OVT domain according to an embodiment of the present invention;

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

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

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

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

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

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

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

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

[0045] Fig.10 is a five-dimensional travel time diagram of the reflected P wave in the OVT domain of model 2 according to an embodiment of the present invention;

[0046] Fig.11 is a graph of the percentage error of the five-dimensional travel time in the OVT domain of the reflected P wave of Model 2 according to an embodiment of the present invention;

[0047] Fig.12 is a diagram showing the normal time difference correction result of the five-dimensional travel time in the OVT domain of the reflected P wave of model 2 according to an embodiment of the present invention;

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

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

[0050] Fig.15 is a diagram showing the normal time difference correction result of the five-dimensional travel time in the OVT domain of the reflected P wave of Model 3 according to an embodiment of the present invention;

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

[0052] Fig.17 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0054] Embodiment 1:

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

[0056] In this embodiment, a method for calculating the five-dimensional P-wave travel time of arbitrary anisotropic media in an OVT domain is provided. Figure 1 is a flow chart of a method for calculating five-dimensional P-wave travel time of arbitrary anisotropic medium in OVT domain according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0057] Step S101, set the global coordinate system of the formation and establish a cross-arranged orthogonal observation system, determine the offset vector slice domain in the orthogonal observation system, the offset vector slice domain includes multiple offset vector slices (OVT slices), each vector slice corresponds to an offset and an azimuth.

[0058] In an optional embodiment, a Cartesian coordinate system is assumed as the global coordinate system, in which the x3 axis is in the vertical direction, and the x1 and x2 axes are in the horizontal direction and are orthogonal to each other; the background medium is a uniform stratum, and the horizontal reflection surface at the bottom of the stratum is parallel to the (x1, x2) plane.

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

[0060] In a single cross subset, seismic traces whose shot points and receiver points have a fixed center range can be combined into an OVT slice. Each OVT slice represents an offset and azimuth within a certain range. Figure 3The same OVT slices in different cross subsets form an OVT domain. Each OVT domain is a single coverage profile within the work area, and a single OVT slice represents a specific position in the OVT domain.

[0061] Step S102, dividing the offset vector slice domain in the polar coordinate system according to the offset angle and azimuth of each offset vector slice to obtain a five-dimensional observation system.

[0062] When grouping OVT domains, in the Cartesian coordinate system, the data is arranged as follows Figure 4 As shown. Figure 4 In the OVT domain grouping process shown in FIG, only the coordinates x and y are grouped in the three-dimensional coordinate system, so the offset and azimuth of the OVT domain are not uniformly changed. Therefore, in the embodiment of the present invention, the OVT domain should be divided in the polar coordinate system considering the offset and azimuth changes of the OVT domain. The grouping rules when dividing the OVT domain in the polar coordinate system are as follows: Figure 5 shown.

[0063] After dividing the OVT domain in the polar coordinate system, the obtained five-dimensional observation system is as follows: Figure 6 As shown, Figure 6 The triangle symbol in the figure represents the position of the OVT piece. Each OVT piece has its corresponding seismic source, which is located at a position that is centrally symmetrical with the detector.

[0064] Step S103, in the five-dimensional observation system, the travel time of the reflected wave of each offset vector slice in the offset vector slice domain is calculated according to the offset and azimuth of each offset vector slice.

[0065] Step S104, extracting offset vector slice gathers.

[0066] In an optional embodiment, the OVT gathers are obtained by arranging the data in the order of azimuth angle and offset distance.

[0067] Step S105, 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.

[0068] The method for calculating the five-dimensional P-wave travel time of arbitrary anisotropic media in the OVT domain provided by the embodiment of the present invention solves the problem of travel time processing of complex anisotropic media in wide-azimuth seismic exploration. Information such as azimuth and offset are taken into account in the travel time calculation process, so it has important reference value in wide-azimuth seismic interpretation. At the same time, the normal time difference correction technology can distinguish the time difference caused by offset and azimuth while ensuring accuracy, laying the foundation for subsequent anisotropic parameter inversion. Geophysical data processing personnel can calculate the OVT gathers of complex anisotropic media under the five-dimensional observation system according to the embodiment of the present invention, and can also develop anisotropic parameter inversion methods according to the method provided by the embodiment of the present invention.

[0069] Embodiment 2:

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

[0071] Step a1, calculating the anisotropic parameters of the medium according to the density normalization coefficient matrix of the formation medium and the preset P-wave phase velocity.

[0072] In an optional embodiment, the anisotropic parameters of the medium include the difference between the P-wave phase velocity of the medium in the directions of coordinate axes x1, x2, and x3 and α, where α is a preset P-wave phase velocity, which, for example, can be the P-wave phase velocity in a reference isotropic medium; the gradient of change of the P-wave velocity of the medium in the directions of coordinate axes x1, x2, and x3; the degree to which the P-wave deviates 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 parameter of the medium is calculated by the following formula:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Among them, A ij represents the element in the density normalized stiffness coefficient matrix, α is the preset P-wave phase velocity, ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity and α in the direction of coordinate axis x1, x2, and x3; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 Respectively represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2). S waves refer to waves whose vibration direction is perpendicular to the propagation direction. When S waves propagate along the interface between two media, the vibration direction of fast shear waves is parallel to the interface, and the vibration direction of slow shear waves is perpendicular to the interface. In the embodiments of the present invention, the medium interface is not involved. The P wave is a longitudinal wave that propagates and vibrates along the x3 axis. ξ 16 ,ξ 26 They respectively represent the degree of deviation between the P-wave direction of the longitudinal wave that propagates and vibrates along the Z-axis and the S-wave that propagates along the Z-axis and vibrates along the x1 and x2 axes.

[0084] Step a2, calculating the layer thickness normalized offset of each offset vector slice according to the offset of each offset vector slice and the depth of the horizontal reflection surface.

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

[0086]

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

[0088] Step a3, calculating the zero-offset two-way travel time of each offset vector slice according to the depth of the horizontal reflection surface and the preset P-wave phase velocity.

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

[0090]

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

[0092] Step a4, calculating the reflection wave travel time of each offset vector slice according to the zero offset two-way travel time, the layer thickness normalized offset of each offset vector slice, the azimuth of each offset vector slice and the anisotropy parameter.

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

[0094]

[0095] Where T0 is the two-way travel time at zero offset, is the normalized offset of the offset vector slice by layer thickness, is the P-wave azimuthal anisotropic velocity factor:

[0096]

[0097] ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity of the medium in the coordinate axis x1, x2, and x3 directions and the preset P-wave phase velocity α; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2); Indicates the azimuth of the offset vector patch.

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

[0099] Step b1, determining the reference orientation of each offset vector slice.

[0100] Step b2, calculating the first travel time of each offset vector slice according to the layer thickness normalized offset and the reference azimuth of each offset vector slice.

[0101] Step b3, calculating the second travel time of each offset vector slice when the layer thickness normalized offset is 0 according to the reference azimuth of each offset vector slice.

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

[0103] Step b4, calculating the correction amount of each offset vector slice according to the difference between the first travel time and the second travel time of each offset vector slice.

[0104] Step b5, calculating the corrected reflected wave travel time of each offset vector slice according to the difference between the reflected wave travel time of each offset vector slice and the correction amount.

[0105] For example, if the x1 direction is determined as the reference direction in the normal time difference correction process, that is, direction, then:

[0106] The first travel time of the ith VOT slice calculated based on the normalized offset distance and reference azimuth of the ith VOT slice is:

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

[0108] The correction amount of the i-th VOT slice calculated based on the difference between the first travel time and the second travel time is:

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

[0110] The method of correcting the travel time of the reflected wave in the embodiment of the present invention can eliminate the bending of the event axis caused by the increase of the offset distance, laying a foundation for analyzing the azimuthal anisotropy of the medium.

[0111] In a specific embodiment, the travel time calculation method for the five-dimensional P-wave travel time of arbitrary anisotropic media in the OVT domain provided in the above embodiment is used to perform travel time calculation in a tilted transverse isotropic medium, and the tilted transverse isotropic medium has a symmetry axis. Table 1 is the medium model parameters used in the numerical verification process of the embodiment of the present invention. The model includes a set of 6×6 stiffness coefficient matrices. The matrix is ​​symmetric along the diagonal elements, so only the upper triangular matrix is ​​displayed.

[0112] Table 1

[0113]

[0114] Table 2 shows the reference speed 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 figure, the light solid line represents the precise travel time calculated using the software package ANRAY, and the dark dotted line represents the travel time calculated using the method of the present invention. Figure 8 is the percentage error between the accurate travel time and the travel time calculated by the method provided in the above embodiment. Figure 8 It can be seen that the travel time error calculated by the present invention is within 5%, which meets the production requirements. Fig. 9 The OVT domain travel time after normal time difference correction according to the method provided by the present invention is shown in the figure. The azimuth travel time varies periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0118] In a specific embodiment, the travel time calculation method of the five-dimensional P wave in an arbitrary anisotropic medium in the OVT domain provided in the above embodiment is used to calculate the travel time in an orthotropic medium, and the orthotropic medium has two symmetry planes. Table 3 is the medium model parameters used in the numerical verification process of the present invention. The model includes a set of 6×6 stiffness coefficient matrices. The matrix is ​​symmetric along the diagonal elements, so only the upper triangular matrix is ​​displayed.

[0119] Table 3

[0120]

[0121] Table 4 shows the reference speed 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] Fig.10 In the figure, the light solid line represents the precise travel time calculated using the software package ANRAY, and the dark dotted line represents the travel time calculated using the method of the present invention. Fig.11 is the percentage error between the accurate travel time and the travel time calculated by the method provided in the above embodiment. Fig.11 It can be seen that the travel time error calculated by the present invention is within 5%, which meets the production requirements. Fig.12 The OVT domain travel time after normal time difference correction according to the method provided by the present invention is shown in the figure. The azimuth travel time varies periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0125] In a specific embodiment, the five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain provided in the above embodiment is used to perform travel time calculation in a triclinic anisotropic medium. The triclinic anisotropic medium has three non-orthogonal symmetry planes. In the stiffness coefficient matrix of the triclinic anisotropic medium, all elements are non-zero values, so it can represent the most complex anisotropy. Table 5 is the medium model parameters used in the numerical verification process of the present invention. The model includes a set of 6×6 stiffness coefficient matrices. The matrix is ​​symmetric along the diagonal elements, so only the upper triangular matrix is ​​displayed.

[0126] Table 5

[0127]

[0128] Table 6 shows the reference speed 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] Fig.13 In the figure, the light solid line represents the precise travel time calculated using the software package ANRAY, and the dark dotted line represents the travel time calculated using the method of the present invention. Fig.14 is the percentage error between the accurate travel time and the travel time calculated by the method provided in the above embodiment. Fig.14 It can be seen that the travel time error calculated by the present invention is within 5%, which meets the production requirements. Fig.15 The OVT domain travel time after normal time difference correction according to the method provided by the present invention is shown in the figure. The azimuth travel time varies periodically with the azimuth angle, and the fluctuation amplitude increases with the increase of the offset distance.

[0132] Embodiment three:

[0133] In this embodiment, a five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in the OVT domain is also provided, and the device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

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

[0135] The orthogonal observation system establishment module 161 is used to set the global coordinate system of the formation and establish a cross-arranged orthogonal observation system, and determine the offset vector slice domain in the orthogonal observation system. The offset vector slice domain includes multiple offset vector slices, and each vector slice corresponds to an offset and an azimuth.

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

[0137] The reflection wave travel time calculation module 163 is used to calculate the reflection wave travel time of each offset vector slice in the offset vector slice domain according to the offset and azimuth of each offset vector slice in the five-dimensional observation system.

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

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

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

[0141] The anisotropic parameter calculation unit is used to calculate the anisotropic parameters of the medium according to the density normalization coefficient matrix of the formation medium 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 slice according to the offset of each offset vector slice and the depth of the horizontal reflection 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 slice according to the depth of the horizontal reflection surface and the preset P-wave phase velocity.

[0144] The reflection wave travel time calculation unit is used to calculate the reflection wave travel time of each offset vector slice in the offset vector slice domain according to the zero offset two-way travel time, the layer thickness normalized offset of each offset vector slice, the azimuth of each offset vector slice and the anisotropy parameter.

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

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

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

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

[0149] The correction amount calculation unit is used to calculate the correction amount of each offset vector slice according to the difference between the first travel time and the second travel time of each offset vector slice.

[0150] The reflection wave travel time correction unit is used to calculate the corrected reflection wave travel time of each offset distance vector slice according to the difference between the reflection wave travel time of each offset distance vector slice and the correction amount.

[0151] In some optional embodiments, the anisotropy parameter of the medium is calculated by the following formula:

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161] Among them, A ij represents the element in the density normalized stiffness coefficient matrix, α is the preset P-wave phase velocity, ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity and α in the direction of coordinate axis x1, x2, and x3; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They respectively represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2).

[0162] In some optional embodiments, the layer thickness normalized offset of the offset vector slice is calculated by the following formula:

[0163]

[0164] in, is the normalized offset of the layer thickness, x is the offset of the offset vector slice, and H is the depth of the horizontal reflection surface.

[0165] In some optional 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 reflection surface, and α is the preset P-wave phase velocity.

[0168] In some optional implementations, the travel time of the reflected wave of the offset vector slice is calculated by the following formula:

[0169]

[0170] Where T0 is the two-way travel time at zero offset, is the normalized offset of the layer thickness in the offset vector patch domain, is the P-wave azimuthal anisotropic velocity factor:

[0171]

[0172] ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity of the medium in the coordinate axis x1, x2, and x3 directions and the preset P-wave phase velocity α; η x , η y , η z They represent the change gradient of the P wave velocity of the medium in the coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2); Indicates the azimuth of the offset vector patch.

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

[0174] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

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

[0176] See also Fig.17 , Fig.17 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.17 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.17 A processor 10 is taken as an example.

[0177] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0178] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0179] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created by the use of a computer device based on the presentation of a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0180] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a 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, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Fig.17 The example of connecting through bus is taken in the following.

[0182] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0183] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

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

Claims

1. A method for calculating five-dimensional P-wave travel time in arbitrary anisotropic media in OVT domain, characterized in that: The method comprises: A global coordinate system of the formation is set and a cross-arranged orthogonal observation system is established. An offset vector slice domain is determined in the orthogonal observation system. The offset vector slice domain includes a plurality of offset vector slices, each vector slice corresponding to an offset and an azimuth. The offset vector slice domain is divided in the polar coordinate system according to the offset angle and azimuth of each offset vector slice, and a five-dimensional observation system is obtained; In the five-dimensional observation system, the travel time of the reflected wave of each offset vector slice in the offset vector slice domain is calculated according to the offset and azimuth of each offset vector slice; Extract offset vector slice gathers; The normal time difference correction is performed on the reflection wave travel time of each offset vector slice in the offset vector slice gather to obtain the corrected reflection wave travel time.

2. The method according to claim 1, characterized in that The calculation of the reflected wave travel time of each offset vector slice in the offset vector slice domain according to the offset angle and azimuth of each offset vector slice includes: Calculate the anisotropic parameters of the medium according to the density normalization coefficient matrix of the formation medium and the preset P-wave phase velocity; Calculate the layer thickness normalized offset of each offset vector slice according to the offset of each offset vector slice and the depth of the horizontal reflection surface; The zero-offset two-way travel time of each offset vector slice is calculated according to the depth of the horizontal reflection surface and the preset P-wave phase velocity; The reflection wave travel time of each offset vector slice in the offset vector slice domain is calculated based on the zero-offset two-way travel time, the layer thickness normalized offset of each offset vector slice, the azimuth of each offset vector slice and the anisotropy parameter.

3. The method according to claim 1, characterized in that The normal time difference correction is performed 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, including: Determine the reference orientation of each offset vector slice; Calculate the first travel time of each offset vector slice according to the layer thickness normalized offset and reference azimuth of each offset vector slice; The second travel time of each offset vector slice when the layer thickness is normalized to zero is calculated according to the reference azimuth of each OVT body; Calculate the correction amount of each offset vector slice according to the difference between the first travel time and the second travel time of each offset vector slice; The corrected reflected wave travel time of each offset vector slice is calculated based on the difference between the reflected wave travel time of each offset vector slice and the correction amount.

4. The method according to claim 2, characterized in that: The anisotropy parameters of the medium are calculated by the following formula: Among them, A ij represents the element in the density normalized stiffness coefficient matrix, α is the preset P-wave phase velocity, ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity and α in the direction of coordinate axis x1, x2, and x3; η x , η y , η z They represent the variation gradient of the P wave velocity of the medium in the directions of coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They respectively represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2).

5. The method according to claim 2, characterized in that: The layer thickness normalized offset of the offset vector slice is calculated by the following formula: in, is the normalized offset of the layer thickness, x is the offset of the offset vector slice, and H is the depth of the horizontal reflection surface.

6. The method according to claim 2, characterized in that The zero offset two-way travel time is calculated using the following formula: Where T0 is the zero-offset two-way travel time, H is the depth of the horizontal reflection surface, and α is the preset P-wave phase velocity.

7. The method according to claim 2 or 4 or 5 or 6, characterized in that: The travel time of the reflected wave of the offset vector slice is calculated by the following formula: Where t0 is the two-way travel time at zero offset, is the normalized offset of the offset vector slice by layer thickness, is the P-wave azimuthal anisotropic velocity factor: ε x , ε y , ε z Respectively represent the difference between the P-wave phase velocity of the medium in the coordinate axis x1, x2, and x3 directions and the preset P-wave phase velocity α; η x , η y , η z They represent the variation gradient of the P wave velocity of the medium in the directions of coordinate axes x1, x2, and x3 respectively; z Indicates the degree to which the P wave deviates from the axial direction in the plane (x1, x2); ξ 16 ,ξ 26 They represent the degree of deviation between the P wave direction and the fast and slow S wave directions in the plane (x1, x2); Indicates the azimuth of the offset vector patch.

8. A five-dimensional P-wave travel time calculation device for arbitrary anisotropic media in an OVT domain, characterized in that: The device comprises: An orthogonal observation system establishment module is used to set a global coordinate system of the formation and establish a cross-arranged orthogonal observation system, in which an offset vector slice domain is determined, wherein the offset vector slice domain includes a plurality of offset vector slices, each vector slice corresponding to an offset and an azimuth; A five-dimensional observation system establishment module is used to divide the offset vector slice domain in the polar coordinate system according to the offset angle and azimuth of each offset vector slice to obtain a five-dimensional observation system; A reflection wave travel time calculation module is used to calculate the reflection wave travel time of each offset vector slice in the offset vector slice domain according to the offset and azimuth of each offset vector slice in the five-dimensional observation system; The gather extraction module is used to extract offset vector slice gathers; The reflection wave travel time correction module is used to perform normal time difference correction on the reflection wave travel time of each offset vector slice in the offset vector slice gather to obtain the corrected reflection wave travel time.

9. A computer device, characterized in that: include: 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 five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the five-dimensional P-wave travel time calculation method for arbitrary anisotropic media in the OVT domain according to any one of claims 1 to 7.

Images