OVT domain three-dimensional VSP multi-wave combined imaging method and device

Abstract

The application provides an OVT domain three-dimensional VSP multi-wave joint imaging method, comprising the following steps: determining an initial velocity model according to downgoing P-wave and downgoing S-wave first arrivals of a zero-offset shot gather; determining a shot point and an imaging point, dividing a plurality of azimuth sectors according to the azimuth of the shot point relative to the imaging point, and generating OVT common imaging point gathers of each azimuth sector; performing reverse moveout correction on the OVT common imaging point gathers until the OVT common imaging point gathers are horizontal, and generating a second P-wave root-mean-square velocity of a second P-wave-P-wave gather and a second S-wave root-mean-square velocity of a second P-wave-S-wave gather; eliminating the influence of anisotropy of the second P-wave-P-wave gather and the second P-wave-S-wave gather in each azimuth sector on travel time, determining a third P-wave root-mean-square velocity of a third P-wave-P-wave gather and a third S-wave root-mean-square velocity of a third P-wave-S-wave gather, and determining the matching relationship of the third P-wave-P-wave gather and the third P-wave-S-wave gather in the same time domain at the same depth, and jointly imaging.

Description

Technical Field

[0001] The present application relates to the field of VSP seismic exploration technology, and in particular to an OVT domain three-dimensional VSP multi-wave joint imaging method and device. Background Art

[0002] In the three-dimensional (3D) vertical seismic profile (VSP) imaging process, since 3D VSP data are mostly acquired in wide azimuth, the Offset Vector Tile (OVT) migration method used in surface seismic data divides sectors according to the azimuths of shot points and receivers to eliminate the effects of azimuthal anisotropy on travel times. However, in VSP data, the azimuth of the receivers is fixed. Therefore, the OVT migration method used in surface seismic data is no longer applicable. Summary of the Invention

[0003] In view of this, the purpose of the present application is to propose an OVT domain three-dimensional VSP multi-wave joint imaging method and device that overcomes the above problems or at least partially solves the above problems.

[0004] Based on the above objectives, the first aspect of the present application provides an OVT domain three-dimensional VSP multi-wave joint imaging method, comprising:

[0005] The initial velocity model is determined based on the first arrival of the downward P-wave and downward S-wave of the zero-bias shot gather;

[0006] Determining shot points and imaging points, dividing the shot points on the ground into a plurality of azimuth sectors according to their azimuths relative to the imaging points, and generating OVT common imaging point gathers for each of the azimuth sectors based on the initial velocity model;

[0007] Performing reaction correction on the OVT common imaging point gathers and performing velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, and determining a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather;

[0008] determining a travel time reference, eliminating the influence of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determining a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather;

[0009] determining a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, and performing joint imaging;

[0010] Corridor stacking constraints are performed on the joint imaging and the layer matching accuracy of the joint imaging is determined.

[0011] Optionally, determining the initial velocity model based on the first arrivals of the downward longitudinal wave and the downward shear wave of the zero-bias shot gather includes:

[0012] Determining the P-wave layer velocity, S-wave layer velocity, and the P-wave and S-wave velocity ratio based on the first arrivals of the downgoing P-wave and downgoing S-wave of the zero-bias shot gather;

[0013] Determine the P-wave root mean square velocity, S-wave root mean square velocity and the P-wave root mean square velocity ratio respectively according to the P-wave layer velocity, S-wave layer velocity and the P-wave and S-wave velocity ratio;

[0014] An initial velocity model is determined according to the longitudinal wave root mean square velocity, the shear wave root mean square velocity, and the ratio of the longitudinal and shear wave root mean square velocities.

[0015] Optionally, determining a shot point and an imaging point, and dividing a plurality of azimuth sectors according to the azimuth of the shot point on the ground relative to the imaging point, includes:

[0016] Identify multiple shot points located on the ground;

[0017] Determined imaging point;

[0018] The azimuth sectors are formed by dividing the plurality of shot points at equal angles relative to the imaging point.

[0019] Optionally, generating OVT common imaging point gathers for each of the range sectors based on the initial velocity model includes:

[0020] Determine a receiving well, wherein a plurality of geophones are evenly distributed from the wellhead to the bottom of the receiving well;

[0021] Determining a reflection point extending vertically underground from the imaging point;

[0022] In response to any one of the geophones detecting a shear wave and / or a longitudinal wave reflected from the reflection point, a virtual geophone point located on the ground is determined by extending from the reflection point to the geophone toward the ground;

[0023] Determine an offset distance according to the sum of the distances between the shot point and the imaging point and the sum of the distances between the imaging point and the virtual detection point;

[0024] The OVT common imaging point gathers in each of the azimuth sectors are determined according to the offset, the P-wave root mean square velocity, the S-wave root mean square velocity, and the P-wave and S-wave root mean square velocity ratio.

[0025] Optionally, the OVT common imaging point gather includes a first P-wave-P-wave gather and a first P-wave-S-wave gather;

[0026] Performing reaction correction on the OVT common imaging point gathers and performing velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, and determining a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather, including:

[0027] Performing a reaction correction on the first P-wave gather using the P-wave root mean square velocity, and performing velocity analysis iterations until the events of the first P-wave gather in each of the azimuth sectors are horizontal, thereby determining a second P-wave root mean square velocity for generating the second P-wave gather;

[0028] Calculating an average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity;

[0029] performing a reaction correction on the first P-wave-S-wave gather using the average velocity, and performing velocity analysis iterations until the events of the first P-wave-S-wave gathers in each of the azimuth sectors are horizontal, thereby determining and generating a second average velocity for the second P-wave-S-wave gathers;

[0030] A second shear wave root mean square velocity is determined based on the second average velocity and the second longitudinal wave root mean square velocity.

[0031] Optionally, determining a travel time reference, eliminating an effect of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determining a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather include:

[0032] determining traveltimes of the second P-wave gather and the second P-wave gather located on the same event;

[0033] Determine the average value of the travel time, use the average value as the travel time reference, and determine the third P-wave root mean square velocity of the third P-wave-P-wave channel set and the third S-wave root mean square velocity of the third P-wave-S-wave channel set.

[0034] Optionally, based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, determining a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain, and performing joint imaging, including:

[0035] determining a third longitudinal-wave and shear-wave velocity comparison based on the third longitudinal-wave root mean square velocity and the third shear-wave root mean square velocity;

[0036] determining a matching relationship between the third P-wave gather and the third P-wave gather in the same time domain based on a comparison of the third P-wave root mean square velocity, the third S-wave root mean square velocity, and the third P-wave and S-wave velocities;

[0037] superimposing the third P-wave-P-wave gathers and the third P-wave-S-wave gathers in different azimuth sectors according to the matching relationship to form the joint imaging;

[0038] The matching relationship is expressed as:

[0039]

[0040] Among them, V P and γ represent the third P-wave RMS velocity and the third P-wave RMS velocity ratio, respectively. 0(i) represents the third P-wave gather in the i-th time series, where t 0(i) is a vector representing time, i represents the i-th value in the vector, V C represents the third shear wave root mean square velocity, t 0(j) represents the third P-wave gather in the jth time series.

[0041] Optionally, performing corridor stacking constraints on the joint imaging and determining the layer matching accuracy of the joint imaging includes:

[0042] Determining the detector located at the wellhead of the receiving well and separating a fourth P-wave gather and a fourth P-wave gather of a short time window initially arriving at the detector;

[0043] Correcting the fourth P-wave gather and the fourth P-wave gather to an event axis level respectively using the P-wave layer velocity and the P-wave and S-wave velocity ratio;

[0044] Converting the corrected fourth P-wave gather and the corrected fourth P-wave gather into the same time domain as the matching relationship, and superimposing them to generate corridor stack sections;

[0045] The corridor stacking section is inserted into the joint imaging, and the matching accuracy of the joint imaging is determined by constraining the joint imaging using the corresponding relationship between the corridor stacking section and the same event axis of the joint imaging section.

[0046] Optionally, the average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity is expressed as:

[0047]

[0048] in, Indicates azimuth The root mean square velocity of the longitudinal wave, V S represents the shear wave root mean square velocity, Indicates azimuth The ratio of the longitudinal and transverse wave root mean square velocity;

[0049] The reaction correction amount of the average velocity is expressed as:

[0050]

[0051] Where z represents the depth of the reflection point, Indicates azimuth The average speed, Indicates azimuth The offset distance of the shot point, Indicates azimuth The distance between the shot point and the imaging point, x u Indicates the distance between the imaging point and the wellhead of the receiving well.

[0052] In a second aspect of the present application, an OVT domain three-dimensional VSP multi-wave joint imaging device is provided, comprising:

[0053] The initial velocity model module is used to determine the initial velocity model based on the first arrival of the downgoing longitudinal wave and the downgoing shear wave of the zero-bias shot gather;

[0054] A common imaging point gather module is configured to determine a shot point and an imaging point, divide the shot point on the ground into a plurality of azimuth sectors according to the azimuth of the shot point relative to the imaging point, and generate an OVT common imaging point gather for each azimuth sector based on the initial velocity model;

[0055] a velocity update module, configured to perform reaction correction on the OVT common imaging point gathers and perform velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, thereby generating a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather;

[0056] a travel time reference module, configured to determine a travel time reference, eliminate the influence of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determine a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather;

[0057] a joint imaging module, configured to determine a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, and to perform joint imaging;

[0058] The corridor stacking module is used to perform corridor stacking constraints on the joint imaging and determine the layer matching accuracy of the joint imaging.

[0059] As can be seen from the above, the OVT domain three-dimensional VSP multi-wave joint imaging method and device provided by the present application divides the azimuth sectors by the azimuth of the shot point relative to the imaging point, establishes the division criteria for the azimuth sectors based on the pseudo-ground seismic offset of the VSP data, and determines the OVT common imaging point gathers for each azimuth sector; by performing reaction correction on the first P-wave-P-wave and the first P-wave-S-wave in the OVT common imaging point gathers until the phase axis of the OVT common imaging point gathers in each azimuth sector is horizontal, the second P-wave-P-wave gathers and the second P-wave-S-wave gathers in each azimuth sector are obtained. The accurate velocity model of the sector is constructed, that is, the second P-wave RMS velocity and the second S-wave RMS velocity are obtained. Finally, the travel time references of the second P-wave-P-wave gather and the second P-wave-S-wave gather in each azimuth sector are corrected to eliminate the influence of anisotropy on the travel time in each azimuth sector, and the third P-wave RMS velocity of the third P-wave-P-wave gather and the third S-wave RMS velocity of the third P-wave-S-wave gather are generated. In addition, the matching relationship between the accurate third P-wave-P-wave gather and the second P-wave-S-wave gather at the same depth in the same time domain is established to realize multi-wave joint imaging in the same time domain.

[0060] Corridor stacking constraints are imposed on the joint imaging, and the layer matching accuracy of the joint imaging is determined using the corridor stacking constraints.

[0061] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in this application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0063] Figure 1 This is a flow chart of a method 100 for three-dimensional VSP multi-wave joint imaging in the OVT domain according to an embodiment of the present application;

[0064] Figure 2 This is a schematic diagram of an initial velocity model according to an embodiment of the present application;

[0065] Figure 3 A schematic diagram of a 3D VSP propagation path according to an embodiment of the present application;

[0066] Figure 4 This is a schematic diagram of the azimuth division of non-wellhead imaging points in an embodiment of the present application;

[0067] Figure 5 Schematic diagram of the longitudinal-longitudinal wave point gather in the OVT common imaging point gather before reaction correction in an embodiment of the present application;

[0068] Figure 6 Schematic diagram of the second P-wave-P point gather in the OVT common imaging point gather after reaction correction in an embodiment of the present application;

[0069] Figure 7 Schematic diagram of the longitudinal-shear wave point gather in the OVT common imaging point gather before reaction correction in an embodiment of the present application;

[0070] Figure 8 Schematic diagram of the second P-wave-S-wave point gather in the OVT common imaging point gather after reaction correction in an embodiment of the present application;

[0071] Figure 9 A schematic diagram of a spiral gather of the second longitudinal wave-longitudinal wave according to an embodiment of the present application;

[0072] Figure 10 A schematic diagram of a spiral gather of the second longitudinal wave-shear wave according to an embodiment of the present application;

[0073] Figure 11 This is a schematic cross-sectional diagram of the combined imaging of the second longitudinal wave-longitudinal wave and the second longitudinal wave-transverse wave according to an embodiment of the present application;

[0074] Figure 12 This is a schematic diagram of a superimposed cross-section of a corridor according to an embodiment of the present application;

[0075] Figure 13 A schematic diagram of joint imaging of a second longitudinal wave and a longitudinal wave inserted into a corridor stack section according to an embodiment of the present application;

[0076] Figure 14 A schematic diagram of joint imaging of a second longitudinal wave and a shear wave inserted into a corridor stack section according to an embodiment of the present application;

[0077] Figure 15 Schematic diagram of an OVT domain three-dimensional VSP multi-wave joint imaging device according to an embodiment of the present application;

[0078] Figure 16 This is a schematic diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0079] In order to make the objectives, technical solutions and advantages of this application more clear, this application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0080] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the usual meanings understood by people with ordinary skills in the field to which this application belongs. The "first", "second" and similar words used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0081] Zero-offset shot gather, also known as zero-bias shot gather, is a special type of shot gather data in VSP data. Its core feature is that the projected position of the shot point and the receiver in the receiving well on the horizontal plane coincides or nearly coincides, that is, the offset approaches zero.

[0082] Primary-P waves (PP waves): Seismic waves are triggered from the earthquake source in the form of primary (P) waves, and after reflection from the underground interface, they return to the detector in the form of primary waves.

[0083] P-wave-S-wave (PS wave): Seismic waves are triggered from the earthquake source in the form of P-waves, which are reflected from the underground interface and converted into S-waves.

[0084] A coherent event is a continuous waveform sequence in a seismic record consisting of reflected or refracted waves with similar phase characteristics on multiple adjacent traces. This event manifests as a linear or curvilinear pattern of wave crests or troughs arranged continuously in the time-space domain.

[0085] Common Image Gathers (CIGs) are data sets formed by grouping seismic data from different shot points or azimuths around the same underground imaging point according to specific rules in seismic imaging processing.

[0086] according to Figure 1 As shown, an embodiment of the present application provides an OVT domain three-dimensional VSP multi-wave joint imaging method 100, the method comprising:

[0087] S100, determining an initial velocity model based on the first arrivals of the downgoing P-wave and downgoing S-wave of the zero-offset shot gather;

[0088] Specifically, according to the initial arrival of the downward P-wave and downward S-wave of the zero-bias shot gather, the P-wave layer velocity, S-wave layer velocity and the P-S wave velocity ratio are determined; according to the P-wave layer velocity, S-wave layer velocity and the P-S wave velocity ratio, the P-wave root mean square velocity, S-wave root mean square velocity and the P-S wave root mean square velocity ratio are determined respectively; according to the P-wave root mean square velocity, S-wave root mean square velocity and the P-S wave root mean square velocity ratio, the initial velocity model is determined.

[0089] It should be noted that the above-mentioned root mean square (P-wave RMS velocity, S-wave RMS velocity and P-S wave RMS velocity ratio) is a type of velocity model, that is, the initial velocity model can be one or more of the P-wave RMS velocity, S-wave RMS velocity and P-S wave RMS velocity ratio.

[0090] refer to Figure 2 The figure shows the initial velocity model in the embodiment of the present application, wherein a shows the longitudinal wave layer velocity V P , shear wave layer velocity V S , and the longitudinal root mean square velocity RMSV P and shear wave root mean square velocity RMSV S . b shows the ratio of longitudinal and transverse wave velocities V P / V S ratio, and the root mean square velocity ratio of longitudinal and transverse waves RMSV P / V S ratio.

[0091] Seismic waves (simulated by shot points) are usually longitudinal waves, but downward impact will also form shear waves. Ground earthquakes generally cannot receive this shear wave. For the detectors, they are evenly distributed from the wellhead to the bottom of the receiving well. For example, a detector is buried every 20m. The detectors are layered, so each layer can detect the speed of the downward longitudinal wave and downward shear wave excited by the zero-offset shot set, which are the longitudinal wave layer velocity and the shear wave layer velocity. By detecting the shear wave layer velocity and the shear wave layer velocity, it is convenient to calculate the longitudinal wave velocity ratio and the longitudinal wave root mean square velocity ratio. Further, the longitudinal wave layer velocity V obtained by the initial velocity model P , shear wave layer velocity V S , and the longitudinal root mean square velocity RMSV P , shear wave root mean square velocity RMSV S , P-wave velocity ratio V P / V S ratio, and the root mean square velocity ratio of longitudinal and transverse waves RMSV P / V S ratio provides basic velocity parameters for the subsequent generation of OVT common imaging point gathers.

[0092] In step S102, the shot points and imaging points are determined, and multiple azimuth sectors are divided according to the azimuths of the shot points on the ground relative to the imaging points. Based on the initial velocity model, OVT common imaging point gathers are generated for each azimuth sector.

[0093] In the processing of ground seismic data, azimuth sectors are divided according to the offset and azimuth of the shot point and the detector. Unlike ground seismic, in the vertical seismic profile (VSP), the detector is fixed in the receiving well, and the azimuth sector division method in ground seismic cannot be directly used. In the embodiment of the present application, the seismic waves (including longitudinal waves and shear waves) generated by the excitation of shot points in different directions propagate to the same reflection point and then propagate to the detector in the receiving well along the same reflection path, that is, the waves in different directions propagate to the reflection point and then propagate to the detector along the same reflection path. Therefore, the influence of azimuth anisotropy on the travel time of seismic waves is mainly in the propagation stage of the seismic waves descending to the reflection point. In order to divide the azimuth sectors of the flanging, the pseudo-ground seismic offset method is adopted, and the azimuth sectors are divided by the relative azimuth between the shot point and the imaging point of the reflection point on the ground, so as to facilitate the subsequent elimination of the influence of anisotropy on the travel time.

[0094] In some embodiments, determining a shot point and an imaging point, and dividing a plurality of azimuth sectors according to the azimuth of the shot point on the ground relative to the imaging point, includes:

[0095] Identify multiple shot points located on the ground;

[0096] Determined imaging point;

[0097] Azimuth sectors are formed by dividing the positions of multiple shot points relative to the imaging point at equal angles.

[0098] In some exemplary embodiments, the number of shot points is no less than two.

[0099] The purpose of the embodiments of the present application is to further divide the azimuth sectors by the relative azimuth between the shot point and the imaging point, for vertical seismic profiles. When the traditional ground seismic method of dividing the azimuth sectors using the offset and azimuth between the shot point and the detector is not applicable, the azimuth sectors are divided by the relative azimuth between the shot point and the imaging point, thereby facilitating the subsequent elimination of the influence of azimuth anisotropy. Furthermore, for vertical seismic profiles, since the reflection point is located underground, directly dividing the azimuth sectors by the azimuth between the reflection point and the shot point may cause deviations in the division of the azimuth sectors. The division of the azimuth sectors by the imaging point located on the ground in the vertical upward direction of the reflection point can reflect the anisotropy of the shot points from different azimuths relative to the reflection point, while facilitating the division of the azimuth sectors and being more accurate.

[0100] It should be noted that reflection points are used to reflect seismic waves excited by the shot points. In strata at different depths relative to the ground, each stratum has an imaging point. Similarly, there is not necessarily only one reflection point in the same stratum. In the embodiments of the present application, any reflection point can be used to divide the azimuth sectors.

[0101] like Figure 3 As shown in the figure, according to the Kirchhoff prestack time migration theory, the seismic waves generated by the shot points S1, S2 and S3 from different ranges propagate to the same reflection point C, and then propagate to the ground along the same reflection path CR. The imaging point of the reflection point C on the ground is further determined to be C0. The azimuths of the shot points S1, S2 and S3 relative to the imaging point C0 are used to form multiple sectors. Figure 4 , with the azimuth of the Inline line as 0° and the division angle of 45°, the shot point is divided into four azimuth sectors at each imaging point (reflection point): Azimuth I: -22.5°-22.5°, Azimuth II: 22.5°-67.5°, Azimuth III: 67.5°-112.5° and Azimuth IV: 112.5°-157.5°. At the same time, the distances of shot points S1, S2 and S3 from the imaging point C0 are x d1 、x d2 and x d3 .

[0102] In some embodiments, based on the initial velocity model, generating OVT common imaging point gathers for each azimuth sector includes:

[0103] A receiving well is determined, and multiple detectors are evenly distributed along the receiving well from the wellhead to the bottom of the well; a reflection point extending vertically underground from the imaging point is determined; in response to any detector detecting a shear wave and / or a longitudinal wave reflected from the reflection point, a virtual detection point located on the ground is determined by extending from the imaging point to the detector; an offset is determined based on the sum of the distances between the shot point and the imaging point, and between the imaging point and the virtual detection point; and an OVT common imaging point gather within each azimuth sector is determined based on the offset and the longitudinal wave root mean square velocity, the shear wave root mean square velocity, and the ratio of the longitudinal and shear wave root mean square velocities.

[0104] refer to Figure 3 As shown in the figure, after the seismic waves excited by the shot points S1, S2 and S3 propagate downward to the same imaging point C, they propagate along the same reflection path CR to the detector R in the receiving well. In order to form the OVT common imaging point gather, by determining the receiving well, any one of the multiple detectors uniformly distributed from the wellhead to the bottom of the receiving well detects the wave (upgoing longitudinal wave and / or upgoing shear wave) reflected from the reflection point to form a reflection path.

[0105] After determining the reflection path, it is further necessary to determine the offset distance of the common imaging point track set. In the embodiment of the present application, the pseudo-ground seismic offset distance is used as the offset distance in the common imaging point track set. That is, the upgoing shear wave and / or upgoing longitudinal wave reflected from the reflection point to the detector is extended toward the ground to determine the virtual detection point located on the ground. In other words, the virtual detection point located on the ground is determined by extending toward the ground along the reflection path. The sum of the distances between the shot point and the imaging point and between the imaging point and the virtual detection point is used as the offset distance of the common imaging point track set, and the OVT common imaging point track set in each azimuth sector is determined according to the offset distance and the longitudinal wave root mean square velocity, the shear wave root mean square velocity and the longitudinal and shear wave root mean square velocity ratio to determine the common imaging point track set.

[0106] refer to Figure 3 As shown, the distances between the shot points S1, S2 and S3 and the imaging point are x d1 、x d2 and x d3 According to Kirchhoff's prestack time migration theory, taking shot point S2 as an example, the propagation time of the seismic wave with the propagation path S2CR' is:

[0107]

[0108] in, represents the azimuth, and Represents azimuth The propagation time and velocity of the downlink wave from the downshot point to the reflection point, T u and V u They represent the propagation time and propagation speed of the upgoing wave from the reflection point to the virtual detection point, z represents the depth of the reflection point, x u Indicates the distance from the imaging point to the wellhead of the receiving well, z r Indicates the distance between the detector and the wellhead of the receiving well, that is, the depth of the detector that detects the shear wave and / or longitudinal wave reflected from the reflection point. Indicates azimuth The distance between the shot point and the imaging point.

[0109] It should be noted that the downgoing wave refers to the downgoing shear wave and / or downgoing longitudinal wave propagating from the shot point to the imaging point, and the upgoing wave refers to the upgoing shear wave and / or upgoing longitudinal wave reflected by the imaging point.

[0110] The distance from the shot point to the virtual receiver point R' is used as the offset of the common imaging point gather and is expressed as:

[0111]

[0112] where x' u =x u +z r tanθu , (3)

[0113] in, Indicates azimuth The offset distance, Indicates azimuth The distance between the shot point and the imaging point, x' u Indicates the distance between the imaging point and the virtual detection point, x u Indicates the distance between the imaging point and the wellhead of the receiving well, z r Indicates the distance between the detector and the wellhead of the receiving well, θ u Indicates the angle between the reflected shear wave and / or longitudinal wave and the receiving well.

[0114] In step S104, the OVT common imaging point gather is subjected to reaction correction and velocity analysis iterations are performed until the OVT common imaging point gather events in each azimuth sector are horizontal, and the second P-wave root mean square velocity of the second P-wave-P-wave gather and the second S-wave root mean square velocity of the second P-wave-S-wave gather are determined.

[0115] If there is a time difference between the events in different azimuth sectors, it indicates that the azimuthal anisotropy leads to travel time anomalies, that is, the seismic waves (mainly longitudinal waves) excited from shot points at different azimuths propagate to the reflection points at different times. In the OVT common imaging point gathers, the horizontality of the events directly reflects the accuracy of the velocity model. If the events are tilted or curved, the velocity model needs to be iteratively updated until they are horizontal.

[0116] In some embodiments, the OVT common imaging point gather includes a first P-wave gather and a first P-wave gather. The first P-wave gather represents a collection of downgoing P-waves propagating from the shot point to the reflection point and upgoing P-waves propagating from the reflection point to the virtual imaging point; the first P-wave gather represents a collection of downgoing P-waves propagating from the shot point to the reflection point and upgoing S-waves propagating from the reflection point to the virtual imaging point.

[0117] In some embodiments, a reaction correction is performed on the OVT common imaging point gathers, and velocity analysis is iterated until the events of the OVT common imaging point gathers in each azimuth sector are horizontal, and a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather are determined, including:

[0118] The first P-wave gather is corrected for motion using the P-wave root mean square velocity, and velocity analysis is iterated until the events of the first P-wave gather are horizontal in each azimuth sector. The second P-wave root mean square velocity of the second P-wave gather is determined.

[0119] In this step, after the first P-wave-P-wave gather is reaction-corrected using the P-wave root mean square velocity, velocity analysis is performed using the ground seismic reaction correction method until the first P-wave-P-wave gather event axis in each azimuth sector is horizontal. The P-wave root mean square velocity is mainly updated until the first P-wave-P-wave gather event axis in each range sector is horizontal. The P-wave root mean square velocity is updated to the second P-wave root mean square velocity. Similarly, the first P-wave-P-wave gather is updated to the second P-wave-P-wave gather.

[0120] Calculate the average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity;

[0121] The P-wave-S-wave gathers are corrected for motion using the average velocity, and velocity analysis is iterated until the events of the first P-wave-S-wave gathers in each azimuth sector are horizontal, and the second average velocity of the second P-wave-S-wave gathers is determined.

[0122] A second shear-wave root mean square velocity is determined based on the second average velocity and the second longitudinal-wave root mean square velocity.

[0123] Specifically, for the first P-wave-S-wave gather, an equivalent C-wave velocity is used to establish a time-depth relationship. This equates the downgoing P-wave to the upgoing S-wave, allowing the RMS velocity of the upgoing S-wave to be used as the RMS velocity of the downgoing P-wave. In other words, the average velocity of the P-wave RMS velocity and the S-wave RMS velocity is calculated, and this average velocity is used as the equivalent C-wave velocity. With this average velocity, the first P-wave-S-wave gather can be treated as a S-wave gather for reaction correction. The updated average velocity obtained by reaction-correcting the first P-wave-S-wave gather using the average velocity is the second average velocity. Similarly, the first P-wave-S-wave gather is reaction-corrected to the event axis level to obtain the second P-wave-S-wave gather. Similar to the average velocity derived from the P-wave RMS velocity and the S-wave RMS velocity, the reverse deduction is performed: the second S-wave RMS velocity is derived using the second average velocity and the direction of the second P-wave RMS velocity.

[0124] For the first P-wave-P-wave gather and the first P-wave-S-wave gather, the horizontality of the event directly reflects the accuracy of the velocity model. If the event is tilted or curved, the velocity model needs to be iteratively updated until it is horizontal. Therefore, the P-wave root mean square velocity and the average velocity are used for reaction correction respectively. During the correction process, velocity analysis iteration is performed. For example, the velocity analysis iteration can be expressed as making the event curved in the first P-wave-P-wave gather and the first P-wave-S-wave gather horizontal. During the correction process, the P-wave root mean square velocity and the S-wave root mean square velocity are mainly updated. After correction, the event of the first P-wave-P-wave gather and the first P-wave-S-wave gather in each azimuth sector are horizontal, and the second P-wave root mean square velocity and the second S-wave root mean square velocity are obtained. At the same time, the corrected first P-wave-P-wave gather and the corrected first P-wave-S-wave gather are obtained, namely the second P-wave-P-wave gather and the second P-wave-S-wave gather.

[0125] Determine the second longitudinal-wave transverse root mean square velocity ratio according to the second longitudinal-wave root mean square velocity and the second transverse-wave root mean square velocity;

[0126] In some embodiments, the average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity is expressed as:

[0127]

[0128] in, Indicates azimuth The root mean square velocity of the longitudinal wave, V S represents the shear wave root mean square velocity, Indicates azimuth The ratio of the longitudinal and transverse wave root mean square velocity;

[0129] The reaction correction amount of the average velocity is expressed as:

[0130]

[0131] Where z represents the depth of the reflection point, Indicates azimuth The average speed, Indicates azimuth The offset distance of the shot point, Indicates azimuth The distance between the shot point and the imaging point, x u Indicates the distance between the imaging point and the wellhead of the receiving well.

[0132] refer to Figure 5 、 Figure 6 、 Figure 7 and Figure 8As shown, the first P-wave gather in the OVT common imaging point gather before the reaction correction, the second P-wave gather in the OVT common imaging point gather after the reaction correction, the first P-wave gather in the OVT common imaging point gather before the reaction correction, and the second P-wave gather in the OVT common imaging point gather after the reaction correction are shown. (a), (b), (c) and (d) show the Figure 4 Gathers for orientations I, II, III, and IV. (e), (f), (g), and (h) are magnified representations of the red boxes in (a), (b), (c), and (d), respectively. Comparison shows that both the first P-wave gather and the first P-wave gather show more horizontal events after reaction correction. More horizontal events indicate a more accurate velocity model after reaction correction.

[0133] In step S106, the travel time reference is determined, the influence of the anisotropy of the second P-wave-P-wave channel gather and the second P-wave-S-wave channel gather in each azimuth sector on the travel time is eliminated, and the third P-wave root mean square velocity of the third P-wave-P-wave channel gather and the third S-wave root mean square velocity of the third P-wave-S-wave channel gather are determined.

[0134] After obtaining the accurate velocity models of the second P-wave gather and the second P-wave gather in each azimuth sector, there is an obvious time difference between the events at the same layer or depth in the OVT common imaging point gathers of each azimuth sector at the same imaging point. Figure 3 The strata at reflection point C are considered to be in the same layer, but the arrival times at reflection point C are different, resulting in different time domains on the events. This time difference is a travel time anomaly caused by azimuthal anisotropy. If this anomaly is not corrected during the imaging process, the resolution of the resulting joint imaging section will be reduced. To eliminate the impact of travel time anomalies on the joint imaging, it is necessary to correct the travel time of the same event in various azimuths. Based on statistical principles, this correction is performed to the average travel time across all azimuths.

[0135] In some embodiments, determining a travel time reference, eliminating anisotropy effects of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determining a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather include:

[0136] Determine the travel times of the second P-wave-P-wave channel set and the second P-wave-S-wave channel set located on the same in-phase axis; determine the average value of the travel times, use the average value as the travel time reference, and determine the third P-wave root mean square velocity of the third P-wave-P-wave channel set and the third S-wave root mean square velocity of the third P-wave-S-wave channel set.

[0137] In this embodiment, the travel times of events at different azimuths are corrected to an average time using a statistical averaging method, eliminating travel time anomalies on the same event caused by azimuthal anisotropy. This travel time is then used to correct the aforementioned precise velocity model, resulting in a horizon-matched velocity model. This means that the time it takes to reach the same event is the same at different azimuths.

[0138] It can be understood that using the traveltime reference to correct the second P-wave gather and the second P-wave gather to eliminate anisotropy essentially updates the velocities within each azimuth sector. This means updating the second P-wave RMS velocity and the second P-wave RMS velocity to obtain the third P-wave RMS velocity and the third S-wave RMS velocity. Accordingly, the second P-wave gather and the second P-wave gather are updated to generate the third P-wave gather and the third P-wave gather.

[0139] refer to Figure 6 (e), (f), (g) and (h) Figure 8 In (e), (f), (g), and (h), there is an obvious time difference in the point gathers of the same phase axis in different azimuths. This time difference is the travel time anomaly in the same time domain caused by azimuthal anisotropy. For the same phase axis, the travel time of each azimuth sector needs to be corrected to the average travel time of the four azimuths. Figure 9 and Figure 10 The second P-wave gather and the second P-wave gather are shown respectively. The OVT common imaging point gathers at the same imaging point are arranged into spiral gathers according to the offset and azimuth. Figure 9 (a) shows the spiral gather before the second P-wave gather is corrected for travel time reference, i.e., the spiral gather before the second P-wave gather is corrected for anisotropy. Figure 9 (b) shows the spiral gather of the second P-wave gather after the travel time reference is corrected, i.e., the spiral gather of the third P-wave gather. Figure 9 (c) shows Figure 9 The red frame in (a) is enlarged. Figure 9 (d) shows Figure 9 The red frame in (a) is enlarged. Figure 10 (a) shows the spiral gather before the second P-wave-S-wave gather is corrected for travel time reference, i.e., before the second P-wave-S-wave gather is corrected for anisotropy. Figure 10 (b) shows the spiral gather of the third P-wave-S-wave gather, i.e., the spiral gather after the anisotropy correction of the second P-wave-S-wave gather; Figure 10 (c) shows Figure 10 The red frame in (a) is enlarged. Figure 10 (d) shows Figure 10 The red frame in (a) is enlarged. Figure 9 (c) and (d) and Figure 10 Comparison between (c) and (d) shows that after the travel time reference is corrected, that is, after the anisotropy correction, the event travel time errors in different azimuth sectors are eliminated, and the events are straighter and more focused.

[0140] Then in step S108, based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, the matching relationship between the third P-wave-P-wave gather and the third P-wave-S-wave gather at the same depth in the same time domain is determined, and joint imaging is performed.

[0141] After correcting the offset velocity of each azimuth travel time anomaly, it is necessary to establish the layer matching relationship between the third P-wave-P-wave gather and the third P-wave-S-wave gather, that is, the matching relationship at PPt0 in the same time domain.

[0142] In some embodiments, step S108 includes:

[0143] The velocity comparison of the third P-wave and S-wave is determined based on the third P-wave RMS velocity and the third S-wave RMS velocity; the matching relationship between the third P-wave-P-wave gather and the third P-wave-S-wave gather in the same time domain is determined based on the comparison of the third P-wave RMS velocity, the third S-wave RMS velocity and the third P- and S-wave velocities; and the third P-wave-P-wave gather and the third P-wave-S-wave gather in different azimuth sectors are superimposed according to the matching relationship to form a joint imaging.

[0144] The matching relationship is expressed as:

[0145]

[0146] Among them, V P and γ represent the third P-wave RMS velocity and the third P-wave RMS velocity ratio, respectively. 0(i) represents the third P-wave gather in the i-th time series, where t 0(i) is a vector representing time, i represents the i-th value in the vector, V C represents the third shear wave root mean square velocity, t 0(j) represents the third P-wave gather in the jth time series.

[0147] It can be understood that the third P-wave-P-wave gather and the third P-wave-S-wave gather each have their own joint imaging.

[0148] It is understandable that and Both reflect the third P-wave-S-wave gather and the reflection point depth z in the time domain t 0(i) matching relationship. Reflects the third P-wave-S-wave gather and the depth z of the reflection point in the time domain t 0(j) matching relationship.

[0149] For the third P-wave gather, at t 0(j) The imaging depth z in the time domain is the root mean square velocity V of the third P-wave after correcting the travel time base anomaly caused by azimuthal anisotropy. P Decide.

[0150] For the third P-wave-S-wave gather, t at the same depth z 0(i) The time domain is composed of the third P-wave RMS velocity V after the travel time anomaly caused by the correction of azimuthal anisotropy. P and the third P-wave RMS velocity ratio γ. Thus, the third P-wave-P-wave gather and the third P-wave-S-wave gather eliminate the influence of azimuthal anisotropy. According to formula (1), the imaging results of the third P-wave-P-wave gather and the third P-wave-S-wave gather in the OVT domain can be obtained, and the same phase axis is matched in the time-space domain.

[0151] Since the polarity of the third P-wave-P-wave gather is opposite to that of the third P-wave-S-wave gather, if the result of the horizon matching is accurate, that is, the same event is in the time-space domain, the third P-wave-P-wave gather and the third P-wave-S-wave gather are at the same event in the same time domain, the crest of the third P-wave-P-wave gather section corresponds to the trough of the third P-wave-S-wave gather section, and the trough of the third P-wave-P-wave gather section corresponds to the crest of the third P-wave-S-wave gather section.

[0152] Figure 11 The joint imaging sections of the third P-wave gather and the third P-wave gather are shown respectively, where Figure 11 (a) shows the third P-wave gather along Figure 4 Inline line cross-well section, Figure 11 (b) shows the third P-wave-S-wave gather Figure 4 The cross section along the Inline line through the well, Figure 11 (c) shows the third P-wave gather along the Xline through the well section. Figure 11 (d) shows the third P-wave-S-wave channel gather along the X-line through the well section. Figure 11 As can be seen from the imaging sections in (a) and (b), the third P-P gather has opposite polarity to the third P-S gather, and the third P-P gather has slightly higher resolution than the third P-S gather. At the target horizon at the top of the 2.0s-2.2s anticline, both the third P-P gather and the third P-S gather clearly depict the structure of the horizon. Figure 11 (a) and Figure 11In (b), the crest of the third P-wave gather pointed by the red arrow corresponds to the trough of the third P-wave gather, the trough of the third P-wave gather corresponds to the crest of the third P-wave gather, and the inclination of the event axes is consistent. Figure 11 (c) and Figure 11 (d) is identical to the inline profile, with a clear polarity reversal at the arrow position. In the inline profile, the third P-wave gather event shows a discontinuity at the wellhead, making the fault orientation difficult to determine. The third P-wave gather clearly demonstrates the development of the dip at the same location, providing richer information for subsequent interpretation and inversion.

[0153] In step S110 , corridor stacking constraints are applied to the joint imaging and the layer matching accuracy of the joint imaging is determined.

[0154] In order to constrain the 3D VSP data OVT and multi-wave joint imaging, the constraints are performed by multi-wave corridor superposition in the same time domain as the above embodiment.

[0155] Specifically, step S110 includes:

[0156] A detector located at the wellhead of the receiving well is determined and a fourth P-wave gather and a fourth P-wave gather of a short time window initially arriving at the detector are separated; the fourth P-wave gather and the fourth P-wave gather are respectively corrected to the event level using the P-wave layer velocity and the P-S wave velocity ratio; the corrected fourth P-wave gather and the corrected fourth P-wave gather are converted to the same time domain as the matching relationship and are superimposed to generate corridor stacking sections; the corridor stacking section is inserted into the joint imaging, and the corresponding relationship between the same event of the corridor stacking section and the joint imaging section is used to constrain the joint imaging to determine the matching accuracy of the joint imaging.

[0157] The corridor refers to a short time window near the wellhead of the receiving well (for example, 0.5 seconds after the first arrival), where the seismic wave signal in this window is less affected by noise.

[0158] According to the initial velocity model, the signal received by the detector within a short time window starting from the first arrival is the reflected wave signal of the formation at the depth of the detector. Since most VSP sources are P-wave sources and the reflection of the seismic wave occurs at the detector position, which is close to the wellhead of the receiving well, the propagation time of the upgoing wave can be ignored. Therefore, when performing corridor stacking, it is first necessary to separate the upgoing fourth P-wave-P-wave gather and the fourth P-wave-S-wave gather. The upgoing fourth P-wave-P-wave gather and the upgoing fourth P-wave-S-wave gather are directly reflected from the detector at the wellhead to avoid the influence of azimuthal anisotropy. The OVT common imaging gathers are then cropped using a short time window (e.g., 0.5 seconds) after the first arrival of the fourth P-wave and the fourth S-wave from the shot point directly to the geophone. The upgoing fourth P-wave gather and the fourth P-wave gather are then horizontally corrected based on the layer velocity (P-wave layer velocity and P-S wave velocity ratio) obtained from the initial velocity model. At this point, the upgoing fourth P-wave and fourth S-wave fields from the geophone are both one-way trips in the vertical direction. These waves are converted to the same time domain as the matching relationship and superimposed to obtain an accurate corridor stack profile within this time domain at the wellhead. Using the corridor stack profile, which is less affected by noise at the wellhead, the stacked corridor profile can accurately reflect the horizon matching results of the strata at the wellhead within this time domain. Corridor stacking constrains the horizon matching of the joint imaging. By using the corridor stacking sections to compare joint imaging, the events of the corridor stacking sections at the wellhead constrain the joint imaging to be on the same event. That is, the corridor stacking sections are used to constrain the joint imaging to be at the same stratum as the wellhead. This allows for matching of the strata far from the wellhead in the joint imaging.

[0159] If the peaks and troughs of the fourth P-wave gather match the peaks and troughs of the third P-wave gather at the wellhead, and the peaks and troughs of the fourth P-wave gather match the peaks and troughs of the third P-wave gather at the wellhead, the matching is successful. If the peaks and troughs of the fourth P-wave gather do not match the peaks and troughs of the third P-wave gather at the wellhead and / or the peaks and troughs of the fourth P-wave gather do not match the peaks and troughs of the third P-wave gather at the wellhead, the matching fails, and the precise velocity models of the third P-wave gather and the third P-wave gather, that is, the third P-wave root mean square velocity and the third S-wave root mean square velocity, are readjusted until they match.

[0160] It can be understood that, similar to the joint imaging, the fourth P-wave-P-wave gather and the fourth P-wave-S-wave gather each have their own corridor stacking imaging.

[0161] In order to further constrain the results of the joint imaging, the embodiment of the present application uses the corridor superposition imaging results for constraint. Figure 12This is a schematic diagram of the corridor superposition in the embodiment of this application; wherein, Figure 12 (a) and Figure 12 (c) in the figure are the wave fields of the zero-bias upgoing fourth P-wave gather and the fourth P-wave gather, where the red line is the wave field clipping position. After the clipped wave field is corrected to the horizontal using the precise layer velocity at the inlet position, the following can be obtained: Figure 12 (b) and Figure 12 The wave fields of the fourth P-wave gather and the fourth P-wave gather after correction in (d) are converted to the same time domain as the matching relationship, that is, the PP t0 time domain, and the time domain corridor stacking section is obtained, as shown in the figure. Figure 13 As shown in (c), Figure 13 The left part of (c) is the fourth P-wave-P-wave gather corridor stacking section in the PP t0 time domain. Figure 13 The right portion of (c) is the stacked section of the fourth P-wave and S-wave gather corridor in the PP t0 time domain. At the target horizon, the polarities of the events are opposite, and the corresponding horizons are consistent. Figure 13 (a) and Figure 13 (b) shows the results of the fourth P-wave-P-wave gather corridor stacking section embedded in the Inline and Xline sections of the third P-wave-P-wave gather joint imaging, and the phase axis corresponds well at the target layer. Figure 14 (a) and Figure 14 (b) shows the results of the Inline and Xline sections of the fourth P-wave-S-wave gather corridor stacking section embedded in the third P-wave-S-wave gather joint imaging. The target layer phase axes still correspond to each other, indicating that the joint imaging results of the third P-wave-P-wave gather and the third P-wave-S-wave gather in the OVT domain are more accurate.

[0162] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied in a distributed scenario and performed by multiple devices working together. In such a distributed scenario, one of the multiple devices may only perform one or more steps of the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the method.

[0163] It should be noted that the above description is limited to some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in an order different from that described in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0164] Based on the same technical concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides an OVT domain three-dimensional VSP multi-wave joint imaging device.

[0165] refer to Figure 15 The OVT domain three-dimensional VSP multi-wave joint imaging device comprises:

[0166] An initial velocity model module 1501 is used to determine an initial velocity model based on the first arrivals of the downgoing P-wave and downgoing S-wave of the zero-bias shot gather;

[0167] A common imaging point gather module 1502 is configured to determine shot points and imaging points, divide the shot points on the ground into a plurality of azimuth sectors according to their azimuths relative to the imaging points, and generate an OVT common imaging point gather for each of the azimuth sectors based on the initial velocity model.

[0168] a velocity updating module 1503 for performing reaction correction on the OVT common imaging point gathers and performing velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, thereby generating a second P-wave root mean square velocity of the second P-wave gather and a second S-wave root mean square velocity of the second P-wave gather;

[0169] a travel time reference module 1504 for determining a travel time reference, eliminating the influence of anisotropy on the travel time of the second P-wave gather and the second P-wave gather in each azimuth sector, and determining a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather;

[0170] a joint imaging module 1505 for determining a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, and performing joint imaging;

[0171] The corridor stacking module 1506 is used to perform corridor stacking constraints on the joint imaging and determine the layer matching accuracy of the joint imaging.

[0172] For the convenience of description, the above devices are described as being divided into various modules according to their functions. Of course, when implementing this application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0173] The apparatus of the above embodiment is used to implement the corresponding OVT domain three-dimensional VSP multi-wave joint imaging method in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0174] Based on the same technical concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the OVT domain three-dimensional VSP multi-wave joint imaging method described in any of the above embodiments is implemented.

[0175] Figure 16 10 is a schematic diagram showing a more specific hardware structure of an electronic device provided in this embodiment. The device may include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are communicatively connected to each other within the device via the bus 1050.

[0176] The processor 1010 can be implemented using a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0177] The memory 1020 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage devices, dynamic storage devices, etc. The memory 1020 can store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 1020 and is called and executed by the processor 1010.

[0178] The input / output interface 1030 is used to connect input / output modules to implement information input and output. The input / output modules can be configured as components within the device (not shown in the figure) or can be externally connected to the device to provide corresponding functions. Input devices may include a keyboard, mouse, touch screen, microphone, various sensors, etc., and output devices may include a display, speaker, vibrator, indicator light, etc.

[0179] The communication interface 1040 is used to connect to a communication module (not shown) to enable communication between the device and other devices. The communication module can communicate via a wired method (such as USB, network cable, etc.) or a wireless method (such as mobile network, WiFi, Bluetooth, etc.).

[0180] The bus 1050 comprises a path for transmitting information between the various components of the device (eg, the processor 1010 , the memory 1020 , the input / output interface 1030 , and the communication interface 1040 ).

[0181] It should be noted that although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040, and the bus 1050, in a specific implementation, the device may also include other components necessary for normal operation. In addition, it will be understood by those skilled in the art that the above device may only include the components necessary to implement the embodiments of this specification, and does not necessarily include all the components shown in the figure.

[0182] The electronic device of the above embodiment is used to implement the corresponding OVT domain three-dimensional VSP multi-wave joint imaging method in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0183] Based on the same technical concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the OVT domain three-dimensional VSP multi-wave joint imaging method as described in any of the above embodiments.

[0184] The computer-readable media of this embodiment include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0185] The computer instructions stored in the storage medium of the above embodiment are used to enable the computer to execute the OVT domain three-dimensional VSP multi-wave joint imaging method as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0186] Based on the same inventive concept, corresponding to the OVT-domain 3D VSP multi-wave joint imaging method described in any of the above embodiments, the present disclosure further provides a computer program product comprising computer program instructions. In some embodiments, the computer program instructions can be executed by one or more processors of a computer to cause the computer and / or the processors to perform the OVT-domain 3D VSP multi-wave joint imaging method. For each step in each embodiment of the OVT-domain 3D VSP multi-wave joint imaging method, the processor executing the step can be a member of the corresponding execution entity.

[0187] The computer program product of the above embodiment is used to enable the computer and / or the processor to execute the OVT domain three-dimensional VSP multi-wave joint imaging method as described in any of the above embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0188] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. Within the scope of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0189] In addition, for simplicity of description and discussion, and in order not to make the embodiment of the application difficult to understand, the known power supply / ground connection with integrated circuit (IC) chip and other components may or may not be shown in the accompanying drawings provided. In addition, the device can be shown in the form of a block diagram to avoid making the embodiment of the application difficult to understand, and this also takes into account the following fact, that is, the details of the embodiment of these block diagram devices are highly dependent on the platform to be implemented in the embodiment of the application (that is, these details should be fully within the scope of understanding of those skilled in the art). When specific details (for example, circuit) are set forth to describe exemplary embodiments of the application, it will be apparent to those skilled in the art that the embodiment of the application can be implemented without these specific details or when these specific details are changed. Therefore, these descriptions should be considered to be illustrative rather than restrictive.

[0190] Although the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may utilize the embodiments discussed.

[0191] The embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of this application.

Claims

1. A three-dimensional VSP multi-wave joint imaging method in the OVT domain, characterized in that: include: The initial velocity model is determined based on the first arrival of the downward P-wave and downward S-wave of the zero-bias shot gather; Determining shot points and imaging points, dividing the shot points on the ground into a plurality of azimuth sectors according to their azimuths relative to the imaging points, and generating OVT common imaging point gathers for each of the azimuth sectors based on the initial velocity model; Performing reaction correction on the OVT common imaging point gathers and performing velocity analysis iterations until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, thereby generating a second P-wave root mean square velocity of the second P-wave gather and a second S-wave root mean square velocity of the second P-wave gather; determining a travel time reference, eliminating the influence of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determining a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather; determining a matching relationship between the third P-wave gather and the third P-wave gather at the same depth in the same time domain based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, and performing joint imaging; Corridor stacking constraints are performed on the joint imaging and the layer matching accuracy of the joint imaging is determined.

2. The method according to claim 1, characterized in that The determining of the initial velocity model based on the first arrival of the downward longitudinal wave and the downward shear wave of the zero-bias shot gather includes: Determining the P-wave layer velocity, S-wave layer velocity, and the P-wave and S-wave velocity ratio based on the first arrivals of the downgoing P-wave and downgoing S-wave of the zero-bias shot gather; Determine the P-wave root mean square velocity, S-wave root mean square velocity and the P-wave root mean square velocity ratio respectively according to the P-wave layer velocity, S-wave layer velocity and the P-wave and S-wave velocity ratio; An initial velocity model is determined according to the longitudinal wave root mean square velocity, the shear wave root mean square velocity, and the ratio of the longitudinal and shear wave root mean square velocities.

3. The method according to claim 2, characterized in that Determine a shot point and an imaging point, and divide the shot point on the ground into multiple azimuth sectors according to the azimuth of the shot point relative to the imaging point, including: Identify multiple shot points located on the ground; Determined imaging point; The azimuth sectors are formed by dividing the plurality of shot points at equal angles relative to the imaging point.

4. The method according to claim 3, characterized in that Based on the initial velocity model, generating OVT common imaging point gathers of each azimuth sector, including: Determine a receiving well, wherein a plurality of geophones are evenly distributed from the wellhead to the bottom of the receiving well; Determining a reflection point extending vertically underground from the imaging point; In response to any one of the geophones detecting a shear wave and / or a longitudinal wave reflected from the reflection point, a virtual geophone point located on the ground is determined by extending from the reflection point to the geophone toward the ground; Determine an offset distance according to the sum of the distances between the shot point and the imaging point and the sum of the distances between the imaging point and the virtual detection point; The OVT common imaging point gathers in each of the azimuth sectors are determined according to the offset, the P-wave root mean square velocity, the S-wave root mean square velocity, and the P-wave and S-wave root mean square velocity ratio.

5. The method according to claim 4, characterized in that The OVT common imaging point gathers include a first P-wave-P-wave gather and a first P-wave-S-wave gather; Performing reaction correction on the OVT common imaging point gathers and performing velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, and determining a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather, including: Performing a reaction correction on the first P-wave gather using the P-wave root mean square velocity, and performing velocity analysis iterations until the events of the first P-wave gather in each of the azimuth sectors are horizontal, thereby determining a second P-wave root mean square velocity for generating the second P-wave gather; Calculating an average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity; performing a reaction correction on the first P-wave-S-wave gather using the average velocity, and performing velocity analysis iterations until the events of the first P-wave-S-wave gathers in each of the azimuth sectors are horizontal, thereby determining and generating a second average velocity for the second P-wave-S-wave gathers; A second shear wave root mean square velocity is determined based on the second average velocity and the second longitudinal wave root mean square velocity.

6. The method according to claim 5, characterized in that Determining a travel time reference, eliminating the influence of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determining the third P-wave root mean square velocity of the third P-wave gather and the third S-wave root mean square velocity of the third P-wave gather, including: determining traveltimes of the second P-wave gather and the second P-wave gather located on the same event; Determine the average value of the travel time, use the average value as the travel time reference, and determine the third P-wave root mean square velocity of the third P-wave-P-wave channel set and the third S-wave root mean square velocity of the third P-wave-S-wave channel set.

7. The method according to claim 6, characterized in that Based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, determining a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain, and performing joint imaging, including: determining a third longitudinal-wave root mean square velocity ratio of the shear wave according to the third longitudinal-wave root mean square velocity and the third shear-wave root mean square velocity; determining a matching relationship between the third P-wave gather and the third P-wave gather in the same time domain according to the third P-wave root mean square velocity, the third S-wave root mean square velocity, and the third P-wave and S-wave root mean square velocity ratio; superimposing the third P-wave-P-wave gathers and the third P-wave-S-wave gathers in different azimuth sectors according to the matching relationship to form the joint imaging; The matching relationship is expressed as: ， in, and denote the third P-wave RMS velocity and the third S-wave RMS velocity ratio, respectively. Indicates the third P-P gather in the time series, where is a vector representing time, Represents the first values, represents the third shear wave RMS velocity, Indicates the third P-P gather in the A time series.

8. The method according to claim 4, characterized in that Performing corridor stacking constraints on the joint imaging and determining the layer matching accuracy of the joint imaging includes: Determining the detector located at the wellhead of the receiving well and separating a fourth P-wave gather and a fourth P-wave gather of a short time window initially arriving at the detector; Correcting the fourth P-wave gather and the fourth P-wave gather to an event axis level using the P-wave layer velocity and the P-wave and S-wave root mean square velocity ratio, respectively; Converting the corrected fourth P-wave gather and the corrected fourth P-wave gather into the same time domain as the matching relationship, and superimposing them to generate corridor stack sections; The corridor stacking section is inserted into the joint imaging, and the matching accuracy of the joint imaging is determined by constraining the joint imaging using the corresponding relationship between the corridor stacking section and the same event axis of the joint imaging section.

9. The method according to claim 5, characterized in that The average velocity of the longitudinal wave root mean square velocity and the shear wave root mean square velocity is expressed as: ， in, Indicates azimuth The longitudinal wave root mean square velocity, represents the shear wave root mean square velocity, Indicates azimuth The ratio of the longitudinal and transverse wave root mean square velocity; The reaction correction amount of the average velocity is expressed as: ， in, Indicates the depth of the reflection point, Indicates azimuth The average speed, Indicates azimuth The offset distance of the shot point, Indicates azimuth The distance between the shot point and the imaging point, Indicates the distance between the imaging point and the wellhead of the receiving well.

10. An OVT domain three-dimensional VSP multi-wave joint imaging device, characterized in that: include: The initial velocity model module is used to determine the initial velocity model based on the first arrival of the downgoing longitudinal wave and the downgoing shear wave of the zero-bias shot gather; A common imaging point gather module is configured to determine a shot point and an imaging point, divide the shot point on the ground into a plurality of azimuth sectors according to the azimuth of the shot point relative to the imaging point, and generate an OVT common imaging point gather for each azimuth sector based on the initial velocity model; a velocity update module, configured to perform reaction correction on the OVT common imaging point gathers and perform velocity analysis until the events of the OVT common imaging point gathers in each of the azimuth sectors are horizontal, thereby generating a second P-wave root mean square velocity of a second P-wave gather and a second S-wave root mean square velocity of a second P-wave gather; a travel time reference module, configured to determine a travel time reference, eliminate the influence of anisotropy of the second P-wave gather and the second P-wave gather in each azimuth sector on the travel time, and determine a third P-wave root mean square velocity of the third P-wave gather and a third S-wave root mean square velocity of the third P-wave gather; a joint imaging module, configured to determine a matching relationship between a third P-wave gather and the third P-wave gather at the same depth in the same time domain based on the third P-wave root mean square velocity and the third S-wave root mean square velocity, and to perform joint imaging; The corridor stacking module is used to perform corridor stacking constraints on the joint imaging and determine the layer matching accuracy of the joint imaging.

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