A method and device for constructing a shear wave velocity data volume of a formation

Abstract

A method and device for constructing a shear wave velocity data volume of a formation, the method comprising: for each sampling point in four-component waveform data of cross-dipole acoustic logging of a target interval, performing the following operations: determining dipole waveforms in N azimuths according to the four-component waveform data; calculating a bending wave dispersion curve in a frequency domain for each azimuth according to the dipole waveforms in the N azimuths, and calculating shear wave velocity data of the corresponding azimuth by using a dispersion curve constrained inversion technique; interpolating the shear wave velocity data of the N azimuths to obtain interpolated shear wave velocity data corresponding to the sampling point; wherein N is an integer greater than 4; and determining the shear wave velocity data volume of the target interval according to the interpolated shear wave velocity data of all sampling points.

Description

Technical Field

[0001] This article relates to the field of oil and gas exploration technology, and in particular to a method and apparatus for constructing formation shear wave velocity data volumes. Background Technology

[0002] In acoustic wave processing and interpretation, traditional methods generally assume that the shear wave velocity near the wellbore is uniformly distributed at a certain depth. However, in actual drilling operations, factors such as rock mechanical fracturing, wellbore stress concentration, and mud intrusion often cause the near-wellbore formation shear wave velocity to differ from the undisturbed formation shear wave velocity. Shear wave radial velocity profile inversion technology can obtain the formation shear wave velocity at different radial depths near the wellbore, which is of great significance for evaluating formation brittleness and fracturing capability, as well as constructing high-quality initial models for long-range acoustic velocity detection.

[0003] With the increasing complexity of exploration targets and the further application of acoustic logging data, two-dimensional shear wave radial velocity profiles are no longer sufficient to meet the needs of practical applications. Current near-wellbore three-dimensional shear wave velocity analysis methods mainly utilize four-component waveform data measured by array acoustic logging cross-dipole mode, combined with travel-time tomography (CT) technology for wellbore three-dimensional shear wave velocity analysis. However, this method is time-consuming in actual calculations. Therefore, a simple, easy-to-implement, and highly efficient method for constructing formation shear wave velocity data volumes is urgently needed. Summary of the Invention

[0004] This application provides a method and apparatus for constructing a formation shear wave velocity volume. The method uses four-component waveform data from cross-dipole acoustic logging to calculate dipole waveforms in several specified azimuths, employs dispersion curve constraint inversion technology to calculate the radial velocity profile of the shear wave in each azimuth, and uses interpolation of the radial shear wave velocity profiles in multiple azimuths to obtain the three-dimensional shear wave velocity volume of the target segment. This method is simple and easy to implement, has high actual processing efficiency, and is easy to promote and apply.

[0005] In a first aspect, this application provides a method for constructing a formation shear wave velocity data volume, the method comprising:

[0006] Perform the following operations for each sampling point in the four-component waveform data of the cross-dipole acoustic logging of the target layer:

[0007] The dipole waveforms in N azimuths are determined based on the four-component waveform data; the bending wave dispersion curve in the frequency domain is calculated for each of the N azimuths based on the dipole waveforms, and the shear wave velocity data for the corresponding azimuth is calculated using the dispersion curve constraint inversion technique; the shear wave velocity data in the N azimuths are interpolated to obtain the interpolated shear wave velocity data corresponding to the sampling point; wherein, N is an integer greater than 4.

[0008] Based on the interpolated shear wave velocity data from all sampling points, the shear wave velocity data volume of the target layer is determined.

[0009] In one exemplary embodiment, the four-component waveform data of the cross-dipole acoustic logging of the target section are subjected to relevant preprocessing operations, wherein the preprocessing operations include one or more of the following:

[0010] Start time correction, waveform degaussing, and digital filtering.

[0011] In one exemplary embodiment, determining the dipole waveforms in N azimuths based on the four-component waveform data includes:

[0012] Based on the four-component waveform data, the dipole waveforms in N azimuths are calculated using the coordinate rotation equation, wherein the coordinate rotation equation is:

[0013] W(θ)=W XX cos 2 θ+(W XY +W YX sinθcosθ+W YY sin 2 θ

[0014] In the formula, W(θ) is the dipole waveform at azimuth angle θ; θ is the azimuth angle; W XX For the four-component waveform data in the XX direction, W XY For four-component waveform data in the XY direction, W YX W represents the four-component waveform data in the YX direction. YY These are four-component waveform data in the YY direction.

[0015] In one exemplary embodiment, the step of calculating the bending wave dispersion curve in the frequency domain for each of the N azimuths based on the dipole waveforms includes:

[0016] Perform a Fourier transform on the dipole waveform in each of the N directions to obtain the spectrum of the dipole waveform and the conjugate spectrum of the dipole waveform.

[0017] For each angular frequency value, the spectral coherence function is used based on the spectrum of the dipole waveform and the conjugate spectrum of the dipole waveform to determine the spectral coherence function value of the dipole waveform in each set bending wave velocity value. The bending wave velocity corresponding to the maximum value of the spectral coherence function value is taken as the bending wave velocity at that angular frequency.

[0018] The bending wave dispersion curve is obtained based on the bending wave velocity at each angular frequency.

[0019] In one exemplary embodiment, the spectral coherence function is:

[0020]

[0021] In the formula, ρ(ω, V) is the value of the spectral coherence function; X m (ω) represents the spectrum of the dipole waveform; ω is the conjugate spectrum of the dipole waveform; M is the number of receivers in the cross-dipole acoustic logging instrument, and m represents the receiver number; V is the bending wave velocity; ω is the angular frequency; and l is the distance between two adjacent receivers.

[0022] In one exemplary embodiment, the calculation of shear wave velocity data at the corresponding azimuth using dispersion curve constrained inversion technology includes:

[0023] Based on the bending wave dispersion curve, homogeneous stratum dispersion curve and theoretical dispersion curve of each of the N directions, establish the objective function for inverting the thickness and shear wave velocity of the changing zone strata in the radially layered strata model.

[0024] Within the preset values ​​of the change zone stratum thickness and shear wave velocity parameters, the minimum value of the inversion objective function is determined by the least squares method, and the shear wave velocity corresponding to the minimum value is taken as the shear wave velocity of the change zone stratum in that azimuth.

[0025] In one exemplary embodiment, the dispersion curve of the homogeneous layer is determined by the following steps:

[0026] Based on the wellbore radius, formation density, formation P-wave velocity, formation S-wave velocity in the changing zone, well fluid density and fluid velocity, the wave number at different angular frequencies is determined using the dispersion equation of multipole acoustic waves propagating in homogeneous formations.

[0027] Based on the wave number at different angular frequencies, calculate the dispersion curve of the homogeneous layer at the corresponding shear wave velocity.

[0028] In one exemplary embodiment, the objective function for inverting the thickness and shear wave velocity of the varying zone strata in the radially layered stratigraphic model is:

[0029]

[0030] In the formula, E(d, V) S1 ) represents the inversion residual of the objective function; d represents the stratigraphic thickness of the variation zone; V(ω) represents the flexural wave dispersion curve; V s1 V1(ω) represents the shear wave velocity of the changing zone strata; V2(ω, d, V) represents the dispersion curve of the homogeneous .... S1 ) represents the theoretical dispersion curve; Ω represents the pre-set inversion processing frequency band; Ω′ represents the pre-set inversion constraint frequency band; and λ represents the weighting factor.

[0031] In one exemplary embodiment, after calculating the shear wave velocity of the formation in the corresponding azimuth variation zone using dispersion curve constrained inversion technology, the method further includes:

[0032] Based on the shear wave velocity of the changing zone strata and the shear wave velocity of the undisturbed strata, the shear wave velocity of the strata at different radial depths in this azimuth is determined using the formula for shear wave velocity at different radial depths.

[0033] The shear wave velocities of the formation at different radial depths in N directions are determined based on the variation of the shear wave velocity in each azimuth.

[0034] The formula for the formation shear wave velocity at different radial depths is as follows:

[0035]

[0036] In the above formula, V S (r) represents the shear wave velocity at different radial depths; V S2 The shear wave velocity of the original strata; denoted as , where is the shear wave velocity of the change zone obtained from the inversion; 'a' is the wellbore radius; and 'r' is the radial distance from the wellbore wall.

[0037] In one exemplary embodiment, interpolating the N azimuth radial shear wave velocity data to obtain the interpolated shear wave velocity data corresponding to the sampling point includes:

[0038] A polar coordinate model of shear wave velocity in the wellbore is established, and the radial and circumferential directions are discretized into a grid under the polar coordinate model;

[0039] Transform the discretized grid coordinates to a Cartesian coordinate system;

[0040] In a rectangular coordinate system, the shear wave velocities of the formation in N directions are interpolated using an interpolation algorithm to obtain the interpolated shear wave velocity data corresponding to the sampling point.

[0041] The interpolation algorithm is as follows:

[0042] Interpolation in the x-direction:

[0043] Interpolation in the y-direction:

[0044] In the above formula, x = r cosθ, y = r sinθ; (x1, y1) and (x2, y2) are the coordinates of two points, respectively; v is the transverse wave velocity.

[0045] Secondly, embodiments of the present invention provide an apparatus for constructing formation shear wave velocity data volumes. The apparatus includes a memory and a processor. The memory is used to store a program for constructing formation shear wave velocity data volumes, and the processor is used to read and execute the program for constructing formation shear wave velocity data volumes, and execute the method for constructing formation shear wave velocity data volumes as described in any of the above embodiments.

[0046] Thirdly, embodiments of the present invention provide a computer-readable storage medium storing a data processing program, wherein the data processing program is executed by a processor using the method for constructing formation shear wave velocity data volume as described in any of the above embodiments.

[0047] Compared with related technologies, this application provides a method and apparatus for constructing a formation shear wave velocity data volume. The method includes performing the following operations for each sampling point in the four-component waveform data of a cross-dipole acoustic logging of a target formation: determining dipole waveforms in N azimuths based on the four-component waveform data; calculating the bending wave dispersion curve in the frequency domain for each of the N azimuths based on the dipole waveforms, and calculating the shear wave velocity data for the corresponding azimuth using dispersion curve constraint inversion technology; interpolating the shear wave velocity data in the N azimuths to obtain the interpolated shear wave velocity data corresponding to the sampling point; and determining the shear wave velocity data volume of the target formation based on the interpolated shear wave velocity data of all sampling points. This application uses the four-component waveform data of cross-dipole acoustic logging to calculate dipole waveforms in several specified azimuths, uses dispersion curve constraint inversion technology to calculate the radial shear wave velocity data for each azimuth, and uses the radial shear wave velocity data from multiple azimuths for interpolation and reconstruction to quickly construct the three-dimensional shear wave velocity volume of the entire target formation. This method is simple and easy to implement, has high actual processing efficiency, and is easy to promote and apply.

[0048] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0049] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0050] Figure 1 This is a flowchart illustrating the method for constructing formation shear wave velocity data volume according to an embodiment of this application.

[0051] Figure 2 This is a schematic diagram of a device for constructing formation shear wave velocity data volume according to an embodiment of this application;

[0052] Figure 3 These are schematic diagrams of radial double-layer formation models in some exemplary embodiments;

[0053] Figure 4 This is a schematic diagram of the shear wave velocity distribution at a depth point in some exemplary embodiments;

[0054] Figure 5 This is a schematic diagram of the radial shear wave velocity profile of the changing zone strata in some exemplary embodiments. Detailed Implementation

[0055] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0056] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0057] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0058] This invention provides a method for constructing a formation shear wave velocity data volume, such as... Figure 1 As shown, the method includes steps S100-S110, as detailed below:

[0059] Step S100. Perform the following operations for each sampling point in the four-component waveform data of the cross-dipole acoustic logging of the target layer:

[0060] The dipole waveforms in N azimuths are determined based on the four-component waveform data. The bending wave dispersion curve in the frequency domain is calculated for each of the N azimuths based on the dipole waveforms. The shear wave velocity data for the corresponding azimuth is calculated using the dispersion curve constraint inversion technique. The shear wave velocity data in the N azimuths are interpolated to obtain the interpolated shear wave velocity data corresponding to the sampling point.

[0061] Step S110. Determine the shear wave velocity data volume of the target segment based on the interpolated shear wave velocity data of all sampling points.

[0062] In one exemplary embodiment, a multipole array acoustic logging instrument is used to measure the target formation downhole, collect four-component waveform data in cross-dipole measurement mode, and preprocess the four-component waveform data; wherein, the preprocessing operation includes: start time correction, waveform degaussing, and digital filtering, etc.

[0063] In one exemplary embodiment, N is a value determined by the wellbore circumference and a preset interval angle, and N is an integer greater than 4. For example, within the wellbore circumference range of 0-360°, with 15° intervals, N is 24.

[0064] In one exemplary embodiment, determining dipole waveforms in N azimuths based on four-component waveform data includes: calculating dipole waveforms in N azimuths respectively using coordinate rotation equations based on the four-component waveform data; for example: calculating dipole waveforms in 24 azimuths at 15° intervals.

[0065] The equation for the coordinate rotation is:

[0066] W(θ)=W XX cos 2 θ+(W XY +W YX sinθcosθ+W YY sin 2 θ

[0067] In the formula, W(θ) is the dipole waveform at azimuth angle θ; θ is the azimuth angle; W XX For the four-component waveform data in the XX direction, W XY For four-component waveform data in the XY direction, WYX The four-component waveform data in the YX direction, W YY These are four-component waveform data in the YY direction.

[0068] For example: when the azimuth angle is 15°, W(15°) is the dipole waveform at the 15° azimuth angle; when the azimuth angle is 45°, W(45°) is the dipole waveform at the 45° azimuth angle.

[0069] In one exemplary embodiment, the bending wave dispersion curve in the frequency domain for each of the N azimuth dipole waveforms is calculated, including:

[0070] 1. Perform a Fourier transform on the dipole waveform in each of the N directions to obtain the spectrum and conjugate spectrum of the dipole waveform. Performing a Fourier transform on the dipole waveform in each direction yields X. n (ω) represents the spectrum of the dipole waveform. The spectrum of the waveform can be obtained by performing a Fourier transform on the dipole waveform in each orientation. Since the spectrum is a complex number, the conjugate spectrum of the dipole waveform can be obtained by finding the conjugate of the complex number.

[0071] 2. For each angular frequency value, the spectral coherence function is used based on the spectrum of the dipole waveform and the conjugate spectrum of the dipole waveform to determine the spectral coherence function value of the dipole waveform in that azimuth under each set bending wave velocity value.

[0072] Third, the bending wave velocity corresponding to the maximum value of the spectral coherence function is taken as the bending wave velocity at that angular frequency. The spectral coherence function is:

[0073]

[0074] In the formula, ρ(ω, V) is the value of the spectral coherence function; X m (ω) represents the spectrum of the dipole waveform; ω is the conjugate spectrum of the dipole waveform; M is the number of receivers in the cross-dipole acoustic logging instrument, and m represents the receiver number; V is the bending wave velocity; ω is the angular frequency; and l is the distance between two adjacent receivers.

[0075] IV. Obtain the bending wave dispersion curve based on the bending wave velocity at each angular frequency. At each frequency point, a series of coherence function values ​​for the bending wave velocity are calculated. The bending wave velocity corresponding to the maximum value of the coherence function at that frequency is taken as the bending wave velocity at that frequency. This process is repeated for each frequency within a given frequency range to obtain the bending wave dispersion curve. For example, using weighted spectral correlation analysis (i.e., spectral coherence function) in the frequency domain, bending wave dispersion curves in 24 directions are calculated for a dipole waveform.

[0076] In an exemplary embodiment, at each azimuth, based on the characteristics of the flexural wave dispersion curve and the theoretical dispersion curve, the radial shear wave velocity profile at the corresponding azimuth is calculated using dispersion curve constrained inversion technology: Step 1: Based on the flexural wave dispersion curve, homogeneous stratum dispersion curve V1(ω), and theoretical dispersion curve V2(ω, d, V) for each of the N azimuths... S1 Establish the objective function for inverting the thickness and shear wave velocity of radially layered strata;

[0077] In this step, the dispersion curve V1(ω) and the theoretical dispersion curve V2(ω, d, V) of the homogeneous layer are determined. s1 )as follows:

[0078] (1) The dispersion curve V1(ω) of the homogeneous layer is determined by the following steps:

[0079] Based on the wellbore radius, formation density, formation P-wave velocity, formation S-wave velocity in the changing zone, well fluid density and fluid velocity, the wave number at different angular frequencies is determined using the dispersion equation of multipole acoustic waves propagating in homogeneous formations.

[0080] Based on the determined wavenumbers at different angular frequencies, the dispersion curves of the homogeneous formation at the corresponding shear wave velocities are calculated. In this embodiment, the radially varying formation model is simplified to a radially two-layer model, as follows: Figure 3 The diagram shows a radial double-layer formation model. The radial thickness of the formation in the variation zone is d, the radius of the wellbore is a, and r is the radial distance of the formation from the wellbore.

[0081] Under this simplified radial two-layer model, based on the shear wave velocity V of the homogeneous layer... S1 The shear wave velocity in the original formation is obtained by substituting relevant parameters such as wellbore radius, formation density, formation P-wave velocity, shear wave velocity in the changing zone, well fluid density, and fluid velocity into the dispersion equation of multipole acoustic wave propagation in homogeneous formations, and then deriving the shear wave velocity of the homogeneous formation as V. S1 The dispersion curve V1(ω) at time;

[0082] The dispersion equation for multipole sound waves propagating in a homogeneous stratum is:

[0083] D(n, k, ω) = 0

[0084] Where n is the sound source order; k is the wave number; and ω is the angular frequency.

[0085] By solving the dispersion equation D for the wave number at different angular frequencies ω, the shear wave velocity V in the homogeneous layer can be obtained. S1 The dispersion curve V1(ω) at time.

[0086] By substituting the relevant parameters of the altered strata (near-wellbore strata) and the undisturbed strata into the dispersion equation for multipole acoustic wave propagation in radially layered strata, the theoretical dispersion curve V2(ω, d, V) is obtained. S1 );

[0087] The dispersion equation for radially layered strata propagation is:

[0088] D1(n,k,ω)=0

[0089] By using the dispersion equation D1, the wavenumber at different angular frequencies ω can be solved to obtain the theoretical dispersion curve V2(ω, d, V). S1 Where n is the sound source order; k is the wave number; and ω is the angular frequency.

[0090] Currently, commonly used acoustic logging instruments primarily use monopoles, dipoles, and quadrupoles as their sound sources. For a monopole source, n=0; for a dipole source, n=1; and for a quadrupole source, n=2. This invention is based on measurement data from a dipole source, where n is set to 1.

[0091] The second step is to determine the minimum value of the inversion objective function within the preset values ​​of the change zone stratum thickness and shear wave velocity parameters using the least squares method, and take the shear wave velocity corresponding to the minimum value as the shear wave velocity of the corresponding change zone stratum in that azimuth.

[0092] In the radially layered stratigraphic model, the objective functions for inverting the thickness and shear wave velocity of the changing zone strata are:

[0093]

[0094] In the formula, E(d, V) S1 ) represents the inversion residual of the objective function; d represents the stratigraphic thickness of the variation zone; V(ω) represents the flexural wave dispersion curve; V s1 V1(ω) represents the shear wave velocity of the changing zone strata; V2(ω, d, V) represents the dispersion curve of the homogeneous .... S1 ) represents the theoretical dispersion curve; Ω represents the pre-set inversion processing frequency band; Ω′ represents the pre-set inversion constraint frequency band; and λ represents the weighting factor.

[0095] In this step, the pre-set inversion processing frequency band is generally [2500Hz, 7500Hz]; the pre-set inversion constraint frequency band is the high-frequency constraint frequency band for inversion, generally [9000Hz, 10000Hz]; λ is the weighting factor, generally 3 to 4.

[0096] In one exemplary embodiment, after calculating the radial velocity data of the shear wave in the corresponding azimuth using dispersion curve constraint inversion technology,

[0097] Based on the shear wave velocity of the changing zone strata and the shear wave velocity of the undisturbed strata, the shear wave velocity of the strata at different radial depths in this azimuth is determined using the formula for shear wave velocity at different radial depths.

[0098] Based on the variation zone of the shear wave velocity in each azimuth, determine the shear wave velocity (V) at different radial depths in N azimuths. S (r, θ) i )| i＝1～24 );

[0099] The formula for the formation shear wave velocity at different radial depths is as follows:

[0100]

[0101] In the above formula, V S (r) represents the shear wave velocity at different radial depths, V S2 The shear wave velocity of the original strata. The variable zone shear wave velocity is obtained by inversion, where a is the wellbore radius and r is the radial distance from the wellbore wall.

[0102] In one exemplary embodiment, interpolation is performed on the N azimuth radial shear wave velocity data to obtain the interpolated shear wave velocity data corresponding to the sampling point, including:

[0103] The first step is to establish a polar coordinate model of the shear wave velocity in the wellbore, and then perform mesh discretization on the radial and circumferential directions under the polar coordinate model.

[0104] In this step, assuming the wellbore is a regular cylinder with radius a, a polar coordinate model of the shear wave velocity of the formation near the wellbore is established on the cross-section of the wellbore with the center of the cylinder as the origin.

[0105] The second step is to transform the discretized grid coordinates (r, θ) into a rectangular coordinate system (x, y);

[0106] The grid coordinates (r, θ) in the polar coordinate system, representing the radial distance r from the well wall and the azimuth θ, are transformed to the rectangular coordinate system (x, y). The specific transformation relationship is as follows:

[0107]

[0108] The third step involves interpolating the shear wave velocities at N azimuths using an interpolation algorithm within a rectangular coordinate system to obtain the interpolated shear wave velocity data corresponding to the sampling point. For example... Figure 4 The diagram shows a cross-sectional slice of the three-dimensional shear wave velocity volume of the formation near the wellbore, i.e., the change zone, at a certain depth.

[0109] The interpolation algorithm is as follows:

[0110] Interpolation in the x-direction:

[0111]

[0112] Interpolation in the y-direction:

[0113]

[0114] In the above formula, x = r cosθ, y = r sinθ; (x1, y1) and (x2, y2) are the coordinates of two points, respectively; v is the transverse wave velocity.

[0115] Shear wave velocity data were calculated at different depth points until the circumferential and radial shear wave velocity volumes of the changing formation (near the wellbore) within the entire target depth section were constructed. Figure 5 The diagram shows longitudinal slices of the three-dimensional shear wave velocity volume of the strata in the change zone at different azimuths. According to... Figure 4 and Figure 5 As can be seen, the three-dimensional shear wave velocity volume constructed in this embodiment can effectively reflect the spatial distribution of shear wave velocity near the wellbore. Furthermore, by combining azimuth-based shear wave radial velocity profile inversion with spatial interpolation reconstruction techniques, the construction efficiency of the three-dimensional formation shear wave velocity data volume can be significantly improved.

[0116] This disclosure also provides an apparatus for constructing a formation shear wave velocity data volume, such as... Figure 2 As shown, the device includes a memory 200 and a processor 210; the memory is used to store a program for constructing a formation shear wave velocity data volume, and the processor is used to read and execute the program for constructing the formation shear wave velocity data volume, and execute the method described in any of the above embodiments.

[0117] This disclosure also provides a computer-readable storage medium storing a data processing program, which is executed by a processor using the method for constructing formation shear wave velocity data volume as described in any of the above embodiments.

[0118] Example 1

[0119] This example demonstrates the process of constructing a formation shear wave velocity data volume as follows:

[0120] 1) Use a multipole array acoustic logging instrument to measure the target formation downhole, collect four-component waveform data in cross-dipole measurement mode, and preprocess the four-component waveform data.

[0121] 2) Within the 0-360° range around the well, at 15° intervals, the dipole waveforms in 24 azimuths are calculated using the four-component waveform data measured by the cross dipole mode.

[0122] 3) Using weighted spectral correlation analysis, the flexural wave dispersion curves in 24 directions of the dipole waveform are calculated in the frequency domain.

[0123] 4) At each azimuth, based on the characteristics of the actual and theoretical dispersion curves of the flexural wave, the radial shear wave velocity profile at the corresponding azimuth is calculated using the dispersion curve constraint inversion technique.

[0124] 5) Establish a polar coordinate model of near-wellbore shear wave velocity, discretize the model radially and circumferentially, and reconstruct the shear wave velocity at different radial and circumferential positions by interpolating the shear wave velocity at different radial depths in 24 directions.

[0125] 6) Repeat steps 2-6 at different depths until the entire depth range is processed to construct the near-wellbore three-dimensional formation shear wave velocity volume.

[0126] This invention proposes a rapid method for constructing a three-dimensional formation shear wave velocity volume near the wellbore. It calculates dipole waveforms at several specified azimuths using four-component waveform data obtained from array acoustic logging cross-dipole measurement mode. Dispersion curve constraint inversion technology is then used to calculate the shear wave radial velocity profile at each azimuth. Interpolation and reconstruction of the multi-azimuth shear wave radial velocity profiles completes the rapid construction of the three-dimensional shear wave velocity volume for the entire target formation. This method is simple, easy to implement, has high practical processing efficiency, and is suitable for widespread application.

[0127] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A method of constructing a shear wave velocity data volume of a formation, the method comprising: The method includes: Perform the following operations for each sampling point in the four-component waveform data of the cross-dipole acoustic logging of the target layer: The dipole waveforms in N azimuths are determined based on the four-component waveform data; the bending wave dispersion curve in the frequency domain is calculated for each of the N azimuths based on the dipole waveforms, and the shear wave velocity data for the corresponding azimuth is calculated using the dispersion curve constraint inversion technique; the shear wave velocity data in the N azimuths are interpolated to obtain the interpolated shear wave velocity data corresponding to the sampling point; wherein, N is an integer greater than 4. Based on the interpolated shear wave velocity data of all sampling points, the shear wave velocity data volume of the target layer is determined; The calculation of shear wave velocity data at the corresponding azimuth using dispersion curve constrained inversion technology includes: Based on the bending wave dispersion curve, homogeneous stratum dispersion curve and theoretical dispersion curve of each of the N directions, establish the objective function for inverting the thickness and shear wave velocity of the changing zone strata in the radially layered strata model. Within the preset values ​​of the change zone stratum thickness and shear wave velocity parameters, the minimum value of the inversion objective function is determined by the least squares method, and the shear wave velocity corresponding to the minimum value is taken as the shear wave velocity of the change zone stratum in that azimuth.

2. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, The method further includes: Perform relevant preprocessing operations on the four-component waveform data of the cross-dipole acoustic logging of the target layer; The preprocessing operations include one or more of the following: start time correction, waveform degaussing, and digital filtering.

3. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, The step of determining the dipole waveforms in N azimuth directions based on the four-component waveform data includes: Based on the four-component waveform data, the dipole waveforms in N azimuths are calculated using the coordinate rotation equation, wherein the coordinate rotation equation is: In the formula, for Dipole waveform at azimuth angle; This refers to the azimuth angle; This is four-component waveform data in the XX direction. This is four-component waveform data in the XY directions. This is four-component waveform data in the YX direction. These are four-component waveform data in the YY direction.

4. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, The step of calculating the flexural wave dispersion curve in the frequency domain for each of the N azimuth dipole waveforms includes: Perform a Fourier transform on the dipole waveform of each of the N directions to obtain the spectrum of the dipole waveform and the conjugate spectrum of the dipole waveform. For each angular frequency value, the spectral coherence function is used based on the spectrum of the dipole waveform and the conjugate spectrum of the dipole waveform to determine the spectral coherence function value of the dipole waveform in each set bending wave velocity value. The bending wave velocity corresponding to the maximum value of the spectral coherence function value is taken as the bending wave velocity at that angular frequency. The bending wave dispersion curve is obtained based on the bending wave velocity at each angular frequency.

5. The method for constructing a formation shear wave velocity data volume according to claim 4, characterized in that, The spectral coherence function is: In the formula, These are the values ​​of the spectral coherence function; The spectrum of the dipole waveform; is the conjugate spectrum of the dipole waveform; M is the number of receivers in the cross-dipole acoustic logging instrument, and m represents the receiver number; For bending wave velocity; ω is the angular frequency; l is the distance between two adjacent receivers.

6. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, The dispersion curve of the homogeneous layer is determined by the following steps: Based on the wellbore radius, formation density, formation P-wave velocity, formation S-wave velocity in the changing zone, well fluid density and fluid velocity, the wave number at different angular frequencies is determined using the dispersion equation of multipole acoustic waves propagating in homogeneous formations. Based on the wave number at different angular frequencies, calculate the dispersion curve of the homogeneous layer at the corresponding shear wave velocity.

7. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, The objective function for inverting the thickness and shear wave velocity of the varying strata in the radially layered stratigraphic model is: In the formula, d represents the inversion residual of the objective function; d represents the thickness of the formation in the variation zone. The flexural wave dispersion curve; V s1 For the shear wave velocity of the changing zone strata; The dispersion curve is for a homogeneous layer; This is the theoretical dispersion curve; The frequency band for pre-set inversion processing; For the pre-set inversion constraint frequency band; This is the weighting factor.

8. The method for constructing a formation shear wave velocity data volume according to claim 1, characterized in that, After calculating the shear wave velocity of the formation in the corresponding azimuth variation zone using dispersion curve constrained inversion technology, the method further includes: Based on the shear wave velocity of the changing zone strata and the shear wave velocity of the undisturbed strata, the shear wave velocity of the strata at different radial depths in this azimuth is determined using the formula for shear wave velocity at different radial depths. The shear wave velocities of the formation at different radial depths in N directions are determined based on the variation of the shear wave velocity in each azimuth. The formula for the formation shear wave velocity at different radial depths is as follows: In the above formula, For formation shear wave velocities at different radial depths; The shear wave velocity of the original strata; The shear wave velocity of the changed zone obtained by inversion; The radius of the wellbore; This is the radial distance from the well wall.

9. The method for constructing a formation shear wave velocity data volume according to claim 8, characterized in that, The step of interpolating the radial shear wave velocity data in the N directions to obtain the interpolated shear wave velocity data corresponding to the sampling point includes: A polar coordinate model of shear wave velocity in the wellbore is established, and the radial and circumferential directions are discretized into a grid under the polar coordinate model; Transform the discretized grid coordinates to a Cartesian coordinate system; In a rectangular coordinate system, the shear wave velocities of the formation in N directions are interpolated using an interpolation algorithm to obtain the interpolated shear wave velocity data corresponding to the sampling point. The interpolation algorithm is as follows: exist Directional interpolation: ; exist Directional interpolation: ; In the above formula, , (x1,y1) and (x2,y2) are the coordinates of two points; v is the transverse wave velocity.

10. A device for constructing a formation shear wave velocity data volume, characterized in that, The apparatus includes a memory and a processor; the memory is used to store a program for constructing a formation shear wave velocity data volume, and the processor is used to read and execute the program for constructing the formation shear wave velocity data volume, and to execute the method according to any one of claims 1-9.

11. A computer-readable storage medium storing a data processing program, the data processing program being executed by a processor as a method for constructing a formation shear wave velocity data volume according to any one of claims 1-9.

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