CN116125535B - Three-dimensional VSP imaging method and device - Google Patents
Three-dimensional VSP imaging method and device Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/282—Application of seismic models, synthetic seismograms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/30—Analysis
- G01V1/301—Analysis for determining seismic cross-sections or geostructures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/30—Analysis
- G01V1/303—Analysis for determining velocity profiles or travel times
Abstract
The embodiment of the application provides a method and a device for three-dimensional VSP imaging, which relate to the field of seismic exploration, and the method comprises the following steps: acquiring a P wave update speed model; p wave anisotropic offset speed updating is carried out on the P wave updating speed model to obtain a P wave target offset speed model; acquiring an initial gamma model, and correcting the initial gamma model to obtain a target gamma model; and acquiring the PS wave target CIP gather according to the P wave target offset speed model and the target gamma model. According to the embodiment of the specification, the travel time of the seismic wave can be decomposed into the sum of travel time of the downstream traveling wave and travel time of the upstream traveling wave, and the anisotropic effect is corrected through time shifting, so that the non-hyperbolic influence of the travel time of the PP wave and the PS wave under the VSP observation system is eliminated, and the VSP imaging effect can be improved.
Description
Technical Field
The application relates to the field of seismic exploration, in particular to a method and a device for three-dimensional VSP imaging.
Background
In the field of seismic exploration, with the deep development of oil and gas exploration, three-dimensional VSP (Vertical Seismic Profile ) is widely developed, for example, three-dimensional three-component (3D 3C) VSP is received in a well, so that the observation azimuth of any target imaging point is single, the speed of ground PP or PS wave travel time and an anisotropic parameter inversion method in the traditional horizontal lamellar anisotropic medium are not applicable any more, and particularly, the anisotropic medium for developing cracks has a large error in the seismic imaging profile.
Disclosure of Invention
The embodiment of the application aims to provide a three-dimensional VSP imaging method and device, which can decompose the travel time of a seismic wave into the sum of travel times of a downstream wave and an upstream wave, eliminate the non-hyperbolic influence of the travel times of a PP wave and a PS wave under a VSP observation system and improve the effect of three-dimensional VSP imaging by correcting an anisotropic effect through time shifting.
In order to solve the above technical problems, embodiments of the present application are achieved by the following aspects.
In a first aspect, an embodiment of the present application provides a method for three-dimensional VSP imaging, including: acquiring a P wave update speed model, wherein the P wave update speed model is obtained by updating a P wave initial speed model through a P wave isotropic offset speed; p-wave anisotropic migration velocity updating is carried out on the P-wave updating velocity model to obtain a P-wave target migration velocity model, and the P-wave target migration velocity model is used for generating a PP-wave imaging profile according to a PP-wave CIP gather; an initial gamma model is obtained, the initial gamma model is corrected to obtain a target gamma model, and the gamma model is a PP wave T0 time domain P wave to S wave offset speed ratio model; and acquiring a PS wave target CIP gather according to the P wave target offset speed model and the target gamma model, and generating a PS wave imaging section, wherein the PS wave target CIP gather is the PS wave CIP gather after the anisotropic effect of the downlink P wave and the uplink S wave is eliminated.
In a second aspect, an embodiment of the present application provides a three-dimensional VSP imaging apparatus, including: the first acquisition module is used for acquiring a P wave update speed model, wherein the P wave update speed model is obtained by updating a P wave initial speed model through a P wave isotropic offset speed; the updating module is used for updating the P-wave anisotropic migration velocity of the P-wave updating velocity model to obtain a P-wave target migration velocity model, and the P-wave target migration velocity model is used for generating a PP-wave imaging profile according to a PP-wave CIP gather; the second acquisition module is used for acquiring an initial gamma model, correcting the initial gamma model to obtain a target gamma model, wherein the gamma model is a PP wave T0 time domain P wave to S wave offset speed ratio model; the imaging module is used for acquiring a PS wave target CIP gather according to the P wave target offset speed model and the target gamma model and generating a PS wave imaging section, wherein the PS wave target CIP gather is the PS wave CIP gather after the anisotropic effect of the downlink P wave and the uplink S wave is eliminated.
According to the embodiment of the application, a P-wave update speed model is obtained; p wave anisotropic offset speed updating is carried out on the P wave updating speed model to obtain a P wave target offset speed model; acquiring an initial gamma model, and correcting the initial gamma model to obtain a target gamma model; and acquiring the PS wave target CIP gather according to the P wave target offset speed model and the target gamma model. According to the embodiment of the specification, the travel time of the seismic wave can be decomposed into the sum of travel time of the downstream traveling wave and travel time of the upstream traveling wave, and the anisotropic effect is corrected through time shifting, so that the non-hyperbolic influence of the travel time of the PP wave and the PS wave under the VSP observation system is eliminated, and the effect of three-dimensional VSP imaging can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 illustrates a schematic diagram of a model of a three-dimensional VSP provided by an embodiment of the application;
FIG. 2 illustrates a flow diagram of a method for three-dimensional VSP imaging provided by an embodiment of the application;
FIG. 3 illustrates a top view of a three-dimensional VSP-based area to be surveyed provided by an embodiment of the present application;
FIG. 4 shows a schematic diagram of a PP wave CIP trace set according to an embodiment of the application;
FIG. 5 is a schematic diagram of an anisotropically corrected PP wave CIP trace set according to an embodiment of the application;
FIG. 6 shows a contrast schematic of a PP wave imaging profile before and after anisotropic correction according to an embodiment of the present application;
FIG. 7 illustrates another flow diagram of a method for three-dimensional VSP imaging provided by an embodiment of the application;
FIG. 8 is a schematic diagram of a three-dimensional VSP imaging device according to an embodiment of the application;
FIG. 9 is a schematic diagram of another three-dimensional VSP imaging device according to an embodiment of the application;
Detailed Description
In order to make the technical solution of the present application better understood by those skilled in the art, the technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, shall fall within the scope of the application.
Fig. 1 shows a schematic diagram of a three-dimensional VSP according to an embodiment of the present application, where, as shown in fig. 1, a plurality of seismic sources 1 are disposed at preset positions in a region to be explored, and positions of observation wells 2 are disposed at preset positions, for example, coordinates of the observation wells in fig. 1 are (550, 400), a plurality of detection points are vertically disposed in the observation wells 2, depths of the observation wells, positions and intervals of the detection points are all set according to needs, seismic source signals can be sent at each shot point, the seismic source signals can be, for example, rake wavelets with a main frequency of 20Hz, and each detector can respectively acquire reflected waves of the seismic source signals, so as to determine an imaging section of the region to be explored.
The three-dimensional VSP imaging method can be applied to three-dimensional three-component (3D 3C) VSP, but can also be extended to walk 3D3C VSP or multi-azimuth 3C VSP, and has wide application prospect. The present application is illustrated with a three-dimensional three-component 3d3c VSP as an example.
Fig. 2 is a schematic flow chart of a method for three-dimensional VSP imaging according to an embodiment of the present application, which may be performed by a device, such as a server device. In other words, the method may be performed by software or hardware installed on the server device. The service end includes but is not limited to: a single server, a server cluster, a cloud server or a cloud server cluster, and the like. As shown in fig. 2, the method may include the following steps.
And S10, acquiring a P wave update speed model.
The P-wave updating speed model is obtained by updating the P-wave isotropy offset speed through a P-wave initial speed model.
And S20, updating the P-wave anisotropic offset speed of the P-wave update speed model to obtain a P-wave target offset speed model.
The P-wave target offset speed model is used for generating a PP wave imaging section according to the PP wave CIP gather. PP wave means that the incident wave is P wave, and the reflected wave is also P wave.
And S30, acquiring an initial gamma model, and correcting the initial gamma model to obtain a target gamma model.
The gamma model is a P wave-to-S wave offset speed ratio model in a P wave T0 time domain.
PS wave means that the incident wave is P wave, and the reflected wave is S wave, i.e., converted wave. The P-wave update rate model needs to be converted to the PS-wave T0 time domain by the gamma model.
The initial gamma model can be obtained in various modes, for example, the initial gamma model can be obtained by calculation according to zero well source distance VSP data of P waves and S waves, interpolation can also be picked up along a P wave horizon in a PP wave offset section, and therefore the initial gamma model is generated.
And S40, acquiring a PS wave target CIP gather according to the P wave target offset speed model and the target gamma model, and generating a PS wave imaging profile.
The PS wave target CIP gather is the PS wave CIP gather after the anisotropic effect of the downlink P wave and the uplink S wave is eliminated.
By adopting the scheme, the travel time of the seismic wave can be decomposed into the sum of travel times of the downstream traveling wave and the upstream traveling wave, and the anisotropic effect is corrected through time shifting, so that the non-hyperbolic influence of the travel times of the PP wave and the PS wave under the VSP observation system is eliminated, and the effect of three-dimensional VSP imaging can be improved.
In some embodiments, in step S10, the P-wave update rate model may be acquired through the following substeps.
And step 11, acquiring a P-wave initial speed model.
In some possible implementations, the P-wave initial velocity model may be obtained by means of existing knowledge (e.g., zero-well source distance VSP knowledge), such as by picking up on a Z-component record of the zero-well source distance VSP.
And step 12, carrying out isotropic migration velocity update on the P-wave initial velocity model to obtain a P-wave update velocity model.
Because the seismic acquisition is a shot excitation, the multi-point receiving is realized, the distance between the receiving point and the excitation point is increased, and the received reflected wave distance and the propagation time are also increased. The curve relationship between the travel time of a seismic wave from the source to each observation point and the horizontal distance of the observation point from the excitation point is called a time-distance curve. Therefore, in one-point excitation and multi-channel received seismic records, the form of the same phase axis of the reflected wave does not correspond to the form of the underground interface, and the time from self-excitation to self-reception (namely, the time T0) needs to be corrected, so that the reflected wave same phase axis corresponds to the form of the underground interface. The CIP trace set corresponding to the VSP trace may be obtained by mapping the sampling points from the input trace into the CIP (Common Image Point, common imaging point) trace set, superimposed on the time of self-excitation and self-collection (i.e., time T0).
In the time interval curve of the CIP gather, a plurality of in-phase axes can exist, if the time interval curve corresponding to the in-phase axes is a straight line, the P-wave initial speed model is characterized more accurately, and the P-wave initial speed model can be used as a P-wave update speed model. Otherwise, the CIP trace set needs to be subjected to reaction correction, RMS (Root Mean Squared, root mean square) speed analysis is carried out on the CIP trace set subjected to reaction correction, isotropic offset speed update is carried out on the P wave initial speed model, so that the CIP trace set is updated by adopting the updated P wave initial speed model, and the steps are repeated until the time-distance curve of the same phase axis of the CIP trace set is leveled, and the P wave update speed model is obtained.
In some embodiments, in step S20, the P-wave target offset velocity model may be obtained by performing P-wave anisotropic offset velocity update on the P-wave update velocity model through the following substeps.
And 21, dividing the seismic source into a plurality of sector areas at the imaging points according to a preset rule.
Fig. 3 illustrates a top view of a region to be explored based on VSP according to an embodiment of the present application, as shown in fig. 3, a plurality of imaging points 3 may be determined according to an observation well 2, and for any imaging point 3, the seismic source 1 may be divided into a plurality of sector areas 4 according to a preset rule, where the preset rule may be set by a user, for example, a size of dividing the sector areas, an angle corresponding to each sector area, and so on. By dividing the sector area, anisotropic updating of the velocity model can be facilitated. In the top view shown in fig. 3, the source 1 is divided into 8 sectors 4, each sector 4 having an angular extent of 45 °.
And 22, respectively generating a PP wave sub CIP gather in each fan-shaped area according to the P wave update speed model.
In some possible implementations, a target VSP profile corresponding to the target source may be obtained from the VSP profiles according to the target source in the sector, and the PP wave sub CIP gather corresponding to the uplink region may be generated according to the P-wave update rate model and the target VSP profile. Since the speeds of the incident wave and the reflected wave are the same, a PP wave sub CIP trace set can be generated from the P wave update speed model and the target VSP profile.
Fig. 4 shows a schematic diagram of a PP wave CIP trace set according to an embodiment of the present application. As shown in fig. 4, the PP wave sub-CIP trace sets corresponding to different sector areas may have different corresponding time-distance curves, and each PP wave sub-CIP trace set may include multiple in-phase axes, for example, in a PP wave sub-CIP trace set corresponding to an azimuth of 45 ° -90 °, including multiple in-phase axes of 0.35s,0.6s, etc.
Step 23, determining a target sector area from the plurality of sector areas.
The PP wave sub CIP gather corresponding to the target sector area has a phase axis deviation, and the phase axis deviation represents that the deviation between any phase axis of the PP wave sub CIP gather corresponding to the sector area and the corresponding advantage phase axis exceeds a preset deviation threshold.
For example, as shown in fig. 4, the PP wave CIP trace of the sector area corresponding to the azimuth 0-45 ° and the azimuth 270-315 ° is nearly flat, and the in-phase axis is bent down far away, that is, in the time interval curve in fig. 4, the PP wave CIP trace of the sector area corresponding to the azimuth 0-45 ° and the azimuth 270-315 ° has the situation that the time interval curve of the in-phase axis is bent down at the far end with larger offset distance (that is, the deviation from the corresponding dominant in-phase axis exceeds the preset deviation threshold). Therefore, the sector areas corresponding to the orientations 0 to 45 ° and 270 to 315 ° can be regarded as the target sector area.
And step 24, performing first time shift correction on the PP wave sub CIP gather corresponding to the target sector area, and performing root mean square velocity analysis on the corrected PP wave sub CIP gather to obtain a P wave target offset velocity model.
In some possible implementations, the first time shift correction may be performed on the PP wave sub-CIP gather corresponding to the target sector area by equation one (corrected imaging gather time difference equation) as follows.
Wherein DeltaT PP (alpha) is the time shift amount for converting the anisotropic travel time into the isotropic travel time, T PP0 Is T0, x is the offset distance during the double journey of the PP wave picked up on the speed panel,is the offset velocity of the P wave along the crack trend, V P(α) Is the P-wave velocity, eta in the sector P (alpha) is the non-elliptic coefficient of variation with azimuth in the sector area, sin 2 (θ P α) is a sine form of the equivalent emergence angle of the upward P wave in the sector.
Wherein sin 2 (θ P α) can be expressed by the following formula two.
Non-elliptic coefficient eta varying with azimuth angle P The (α) can be determined by the following equation three.
Wherein x is a Correcting the average distance, V, of CIP gathers for mid-to-far offset reaction Pa (α) correct the NMO speed of CIP gather pick-up for mid to far offset reaction within the sector. The above method for determining the middle-to-far offset distance may be determined by a preset threshold, for exampleAll the seismic sources in the sector area can be ranked according to offset, and the offset with a larger offset and a preset proportional threshold (for example, 50%) is used as a middle-to-far offset. An offset greater than a preset absolute offset threshold (e.g., 500 m) may also be used as the mid-to-far offset. The present disclosure is not limited in this regard.
The first time shift correction is to perform P-wave anisotropic time shift correction on PP waves, and fig. 5 shows a schematic diagram of a PP wave sub CIP gather after anisotropic correction according to an embodiment of the present application. As shown in fig. 5, after the first time shift correction is performed on the PP wave sub CIP trace set corresponding to the target sector area, the time-distance curve of the same phase axis of the PP wave sub CIP trace set corresponding to the target sector area is "leveled" in the case of the sag at the far end with a larger offset distance.
In some embodiments, after performing first time shift correction on the PP wave CIP trace set corresponding to the target sector area to obtain the P wave target offset velocity model, the PP wave CIP trace sets of the sector areas in each direction may be superimposed to obtain the PP wave CIP trace set after the anisotropic correction, so as to obtain the PP wave imaging profile after the anisotropic correction.
Fig. 6 shows a PP wave imaging profile contrast schematic diagram before and after anisotropic correction according to an embodiment of the present application. Wherein fig. 6 (a) and fig. 6 (b) are respectively PP wave imaging sectional views before and after anisotropic correction, the amplitude of the PP wave imaging sectional view after anisotropic correction is recovered, the break points of the second to fourth interfaces 5 are clear, the continuity of the fifth interface 6 is better, and the imaging quality of the PP wave imaging sectional view is improved.
By adopting the technical scheme, the travel time of the seismic wave can be decomposed into the sum of travel time of the downstream traveling wave and travel time of the upstream traveling wave, and the anisotropic effect is corrected through time shifting, so that the non-hyperbolic influence of the PP travel time under the VSP observation system is eliminated, and the effect of three-dimensional VSP imaging can be improved.
For an anisotropic medium that develops cracks, it is difficult to describe the anisotropic elastic characteristics using PP wave travel time alone. Inversion of PS wave information excited by a longitudinal wave seismic source is helpful to reveal complex underground anisotropic information such as crack development, interlayer structures and the like, and in some embodiments, the PS wave can be further subjected to anisotropic correction through step S30 and step S40, so that the non-hyperbolic influence of PS wave travel time under a VSP observation system is eliminated.
In some embodiments, in step S30, the initial gamma model may be corrected to obtain the target gamma model through the following substeps.
And 31, dividing the seismic source into a plurality of sector areas at the imaging points according to a preset rule.
Step 31 is similar to step 21 and will not be described again here.
And step 32, respectively generating a first PS wave sub CIP gather in each fan-shaped area according to the P wave target offset velocity model and the initial gamma model.
And 33, performing anisotropic correction of the downlink P waves on the first PS-wave sub-CIP gather corresponding to the fan-shaped area.
In some possible implementations, the anisotropic correction of the downstream P-wave may be performed by the following equation four.
Wherein DeltaT P (alpha) is the time shift amount of converting the anisotropic travel time of the downlink P wave of each sector into the isotropic travel time, z is the depth, x p Is half the offset of the PP wave,is the offset velocity of the P wave along the crack trend, V P(α) Refers to the P-wave velocity, eta in the sector P (alpha) is the non-elliptic coefficient of variation with azimuth in the sector area, sin 2 (θ P α) is a sine form of the equivalent emergence angle of the upward P wave in the sector.
Wherein x is p The method can be calculated by adopting a binary search algorithm according to the following formula five.
And step 34, superposing the first PS wave sub-CIP gather to obtain a first PS wave initial CIP gather.
After the anisotropic correction of the downlink P-wave is performed on the first PS-wave sub-CIP trace set corresponding to each sector area, the first PS-wave sub-CIP trace set after the anisotropic correction of the downlink P-wave may be superimposed to obtain a first PS-wave initial CIP trace set.
And 35, performing second time shift correction and third time shift correction on the first PS wave initial CIP gather to obtain a first PS wave updated CIP gather.
In some possible implementations, the second time shift correction can be performed on the first PS-wave initial CIP trace set by equation six as follows.
Wherein DeltaT C Is the time shift of converted wave, V c Is the velocity of the converted wave, x s Is half of the offset distance of SS wave, V s Is the velocity of the S wave.
Wherein V is s Can be expressed by the following formula seven.
In some possible implementations, the third time shift correction may be performed on the first PS-wave initial CIP trace set after the second time shift correction by the following formula eight, to obtain a first PS-wave updated CIP trace set.
Wherein T is PS0 Is PS wave self-excitation self-time, V C The following formula nine can be used.
And 36, performing root mean square velocity analysis on the first PS wave updated CIP gather to obtain a target gamma model.
After the second time shift correction and the third time shift correction, performing root mean square velocity analysis on the corrected first PS wave update CIP trace set, and obtaining updated V according to the following formula ten C And update T pp0 And T ps0 And obtaining a target gamma model.
Wherein T is ps0 Is self-excitation time of PS wave, T pp0 Is the PP wave self-excitation self-time, i and j are the time sequences of the PP wave and PS wave T0 time domain, respectively.
In some embodiments, in step S40, a PS wave target CIP trace set may be obtained from the P wave target offset velocity model and the target γ model by the following substeps.
And 41, dividing the seismic source into a plurality of sector areas at the imaging points according to a preset rule.
Step 41 is similar to the step of step 21 and will not be described again here.
And 42, respectively determining a second PS wave sub CIP gather according to the P wave target offset velocity model and the target gamma model in each fan-shaped region.
First, an initial PS-wave sub CIP trace set may be generated from the P-wave target offset velocity model and the target gamma model, respectively.
Then, performing time shift correction on the initial PS-wave sub-CIP trace set to obtain a second PS-wave sub-CIP trace set.
The step of performing time shift correction on the initial PS-wave CIP trace set may be referred to as step 33 and step 35, and the corresponding formulas are formula four, formula six and formula eight, respectively. And will not be described in detail herein.
Step 43, dividing the second PS-wave sub-CIP trace set into a first offset PS sub-trace set and a second offset PS sub-trace set according to a preset offset threshold.
For example, a gather with an offset in the second PS-wave sub-CIP gather less than a preset offset threshold may be used as the first offset PS-sub-gather, and a gather with an offset in the second PS-wave sub-CIP gather greater than or equal to the preset offset threshold may be used as the second offset PS-sub-gather.
And step 44, respectively obtaining a first converted wave model and a second converted wave model according to the first offset PS sub-track set and the second offset PS sub-track set.
In some possible implementations, root mean square velocity analysis is performed on the first offset PS sub-track set and the second offset PS sub-track set respectively to obtain a first converted wave model and a second converted wave model, which are respectively used by V C And V' c And (3) representing.
And 45, performing anisotropic correction of the uplink S wave on the second PS wave sub CIP gather corresponding to each sector area according to the first converted wave model and the second converted wave model, and superposing the corrected second PS wave sub CIP gather to obtain a PS wave target CIP gather.
In some possible implementations, the first transformed wave model V may be C And a second converted wave model V' c Substituting formula seven to obtain V s And V' S And the S-wave anisotropy parameter is obtained according to the following formula eleven.
And carrying out the anisotropic correction of the uplink S wave on the second PS wave sub CIP gather corresponding to each sector area according to the S wave anisotropic parameter and the following formula twelve.
And superposing the corrected second PS wave sub CIP trace set to obtain a corrected PS wave target CIP trace set.
In some embodiments, a PS wave imaging profile may be generated according to a PS wave target CIP trace set, and since the PS wave target CIP trace set is a PS wave CIP trace set after the effect of anisotropy of the downlink P wave and the uplink S wave is eliminated, by adopting the above technical solution, the travel time of the seismic wave can be decomposed into the sum of travel times of the downlink wave and the uplink wave, and by correcting the anisotropy effect through time shifting, the non-hyperbolic effect of the travel time of the PS wave in the VSP observation system is eliminated, and the effect of three-dimensional VSP imaging can be improved.
Fig. 7 is a schematic flow chart of another method for three-dimensional VSP imaging according to an embodiment of the present application, where, as shown in fig. 7, the method for three-dimensional VSP imaging may further include:
and S50, performing fast and slow transverse wave separation on the PS wave imaging profile to obtain a target imaging profile.
When an S wave propagates in an anisotropic medium for developing a crack, the S wave splits into two mutually perpendicular polarized components and propagates at different speeds, one is a fast transverse wave with a polarization direction parallel to the crack, the other is a slow transverse wave with a polarization direction perpendicular to the crack, and the in-phase axis on the gather shows a cosine characteristic due to the time difference between the fast transverse wave and the slow transverse wave. The slow and fast transverse waves, if not separated, may cause offset artefacts. The trace sets after the fast and slow transverse waves are separated are flat and straight in phase axis, the imaging quality of the section can be further improved, and the time delay effect of the fast and slow transverse waves can be further utilized to predict crack information.
In some possible implementations, the wave field of the S wave recorded on the R and T components has a partial amplitude projection of the fast and slow transverse waves, and the fast and slow transverse waves need to be rotationally separated by Alford, so as to further obtain the target imaging profile. For stratum containing multi-layer cracks, the quick and slow transverse wave separation needs to be realized by stripping. The PS wave CIP gather can be divided into sub-gathers of a plurality of sector areas, the time window size is fixed, and Alford rotation separation of fast and slow transverse waves is respectively carried out on the sub-gathers of the plurality of sector areas on the R component and the T component from shallow to deep. The energy of the fast transverse wave CIP sub-trace set is enhanced relative to the R component, the energy of the slow transverse wave CIP sub-trace set is obviously weakened relative to the T component, and then the CIP sub-trace sets of a plurality of fan-shaped areas are overlapped to obtain the target imaging profile.
By adopting the technical scheme, the travel time of the seismic wave can be decomposed into the sum of travel time of the downstream wave and travel time of the upstream wave, and the anisotropic effect is corrected through time shifting, so that the non-hyperbolic influence of the travel time of the PP wave and the PS wave under the VSP observation system is eliminated, the fast and slow transverse wave separation can be further carried out, and the effect of three-dimensional VSP imaging can be further improved.
Fig. 8 is a schematic structural diagram of an apparatus for three-dimensional VSP imaging according to an embodiment of the present application, where the apparatus 100 includes: a first acquisition module 110, an update module 120, a second acquisition module 130, and an imaging module 140.
The first obtaining module 110 is configured to obtain a P-wave update speed model, where the P-wave update speed model is obtained by updating a P-wave initial speed model with a P-wave isotropic offset speed;
the updating module 120 is configured to update the P-wave update speed model by using a P-wave anisotropic offset speed to obtain a P-wave target offset speed model, where the P-wave target offset speed model is configured to generate a PP-wave imaging profile according to a PP-wave CIP gather;
the second obtaining module 130 is configured to obtain an initial γ model, correct the initial γ model to obtain a target γ model, where the γ model is a PP wave T0 time domain P wave to S wave offset velocity ratio model;
the imaging module 140 is configured to obtain a PS-wave target CIP gather according to the P-wave target offset velocity model and the target γ model, generate a PS-wave imaging profile, and make the PS-wave target CIP gather be the PS-wave CIP gather after eliminating the anisotropic effects of the downstream P-wave and the upstream S-wave.
In some possible implementations, the first obtaining module 110 is further configured to obtain a P-wave initial velocity model; and carrying out isotropic offset speed update on the P-wave initial speed model to obtain a P-wave update speed model.
In some possible implementations, the updating module 120 is further configured to:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
in each sector area, a PP wave sub CIP gather is respectively generated according to the P wave update speed model;
determining a target sector area from the plurality of sector areas, wherein the PP wave sub CIP gather corresponding to the target sector area has a common-phase axis deviation, and the common-phase axis deviation represents that the deviation between any common-phase axis of the PP wave sub CIP gather corresponding to the sector area and the corresponding dominant common-phase axis exceeds a preset deviation threshold;
and performing first time shift correction on the PP wave sub CIP gather corresponding to the target sector area, and performing root mean square velocity analysis on the corrected PP wave sub CIP gather to obtain a P wave target offset velocity model.
In some possible implementations, the first time-shift corrected imaging gather time difference formula is:
in some possible implementations, the second acquisition module 130 is further configured to:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
in each sector area, respectively generating a first PS wave sub CIP gather according to a P wave target offset speed model and an initial gamma model;
carrying out anisotropic correction of downlink P waves on a first PS wave sub CIP gather corresponding to each fan-shaped area;
superposing the first PS wave sub CIP trace set to obtain a first PS wave initial CIP trace set;
performing second time shift correction and third time shift correction on the first PS wave initial CIP gather to obtain a first PS wave update CIP gather;
and carrying out root mean square velocity analysis on the first PS wave updated CIP gather to obtain a target gamma model.
In some possible implementations, the corrected imaging gather time difference formulas of the anisotropic correction, the second time shift correction and the third time shift correction of the downstream P-wave are respectively
And->
In some possible implementations, the imaging module 140 is further configured to:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
in each sector area, respectively determining a second PS wave sub CIP gather according to the P wave target offset speed model and the target gamma model;
dividing the second PS wave sub-CIP gather into a first offset PS sub-gather and a second offset PS sub-gather according to a preset offset threshold;
respectively obtaining a first converted wave model and a second converted wave model according to the first offset PS sub-track set and the second offset PS sub-track set;
and carrying out anisotropic correction on the uplink S wave on the second PS wave sub CIP gather corresponding to each fan-shaped area according to the first converted wave model and the second converted wave model, and superposing the corrected second PS wave sub CIP gather to obtain a PS wave target CIP gather.
In some possible implementations, the corrected imaging gather time difference equation for the anisotropic correction of the upstream S-wave is:
the imaging module 140 is further configured to:
respectively generating an initial PS wave sub CIP gather according to the P wave target offset speed model and the target gamma model;
and performing time shift correction on the initial PS-wave sub-CIP trace set to obtain a second PS-wave sub-CIP trace set.
The device 100 provided by the embodiment of the application can execute the methods described in the previous method embodiments and realize the functions of the methods described in the previous method embodiments, can decompose the travel time of the seismic wave into the sum of travel times of the downstream wave and the upstream wave, eliminates the non-hyperbolic influence of the travel times of the PP wave and the PS wave under the VSP observation system by correcting the anisotropic effect through time shifting, and can improve the effect of three-dimensional VSP imaging.
Fig. 9 is a schematic structural diagram of another apparatus for three-dimensional VSP imaging according to an embodiment of the present application, where the apparatus 100 further includes:
and the separation module 150 is used for performing fast and slow transverse wave separation on the PS wave imaging profile to obtain a target imaging profile.
The device 100 provided by the embodiment of the application can execute the methods described in the previous method embodiments, realize the functions of the methods described in the previous method embodiments, can decompose the travel time of the seismic wave into the sum of travel time of the downstream wave and the upstream wave, eliminates the non-hyperbolic influence of the travel time of the PP wave and the PS wave under the VSP observation system by correcting the anisotropic effect through time shifting, can further perform fast and slow transverse wave separation, and can further improve the effect of three-dimensional VSP imaging.
In summary, the foregoing description is only of the preferred embodiments of the present application, and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.
Claims (10)
1. A method of three-dimensional VSP imaging, the method comprising:
acquiring a P wave update speed model, wherein the P wave update speed model is obtained by updating a P wave initial speed model through a P wave isotropic offset speed;
p-wave anisotropic migration velocity updating is carried out on the P-wave updating velocity model to obtain a P-wave target migration velocity model, and the P-wave target migration velocity model is used for generating a PP-wave imaging profile according to a PP-wave CIP gather;
an initial gamma model is obtained, the initial gamma model is corrected to obtain a target gamma model, and the gamma model is a PP wave T0 time domain P wave to S wave offset speed ratio model;
and acquiring a PS wave target CIP gather according to the P wave target offset speed model and the target gamma model, and generating a PS wave imaging section, wherein the PS wave target CIP gather is the PS wave CIP gather after the anisotropic effect of the downlink P wave and the uplink S wave is eliminated.
2. The method according to claim 1, wherein the method further comprises:
and performing fast and slow transverse wave separation on the PS wave imaging profile to obtain a target imaging profile.
3. The method of claim 1, wherein the updating the P-wave anisotropic offset velocity model to obtain a P-wave target offset velocity model comprises:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
in each sector area, a PP wave sub CIP gather is respectively generated according to the P wave update speed model;
determining a target sector area from the plurality of sector areas, wherein the PP wave sub CIP gather corresponding to the target sector area has a same-phase axis deviation, and the same-phase axis deviation represents that the deviation between any same-phase axis of the PP wave sub CIP gather corresponding to the sector area and a corresponding dominant same-phase axis exceeds a preset deviation threshold;
and performing first time shift correction on the PP wave sub CIP gather corresponding to the target sector area, and performing root mean square velocity analysis on the corrected PP wave sub CIP gather to obtain the P wave target offset velocity model.
4. The method of claim 3, wherein the first time-shift corrected imaging gather time difference formula is:
wherein DeltaT PP (alpha) is the time shift amount for converting the anisotropic travel time into the isotropic travel time, T PP0 Is T0, x is the offset distance during the double journey of the PP wave picked up on the speed panel,is the offset velocity of the P wave along the crack trend, V P(α) Is the P-wave velocity, eta in the sector P (alpha) is the non-elliptic coefficient of variation with azimuth in the sector area, sin 2 (θ P α) is a sine form of the equivalent emergence angle of the upward P wave in the sector.
5. The method of claim 1, wherein correcting the initial gamma model to obtain a target gamma model comprises:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
respectively generating a first PS wave sub CIP gather in each fan-shaped area according to the P wave target offset speed model and the initial gamma model;
carrying out anisotropic correction of downlink P waves on a first PS wave sub CIP gather corresponding to each fan-shaped area;
superposing the first PS wave sub CIP gather to obtain a first PS wave initial CIP gather;
performing second time shift correction and third time shift correction on the first PS wave initial CIP gather to obtain a first PS wave update CIP gather;
and carrying out root mean square velocity analysis on the first PS wave update CIP gather to obtain the target gamma model.
6. The method of claim 5, wherein the anisotropic correction of the downstream P-wave, the second time shift correction, and the third time shift correction have corrected imaging gather time difference formulas of
And->
Wherein DeltaT P (alpha) is the time shift amount of converting the anisotropic travel time of the downlink P wave of each sector into the isotropic travel time, z is the depth, x is the offset distance, x p Is half the offset of the PP wave,is the offset velocity of the P wave along the crack trend, V P(α) Refers to the P-wave velocity, eta in the sector P (alpha) is the non-elliptic coefficient of variation with azimuth in the sector area, sin 2 (θ P Alpha) is a sine form of an equivalent emergence angle of the upward P wave in the sector area, and delta T C Is the time shift of converted wave, V c Is the velocity of the converted wave, x s Is half of the offset distance of SS wave, V s Is the velocity of S wave, T ps0 Is the self-excitation self-time of PS wave.
7. The method of any one of claims 1 to 6, wherein the acquiring a PS wave target CIP trace set from the P wave target offset velocity model and the target γ model comprises:
dividing a seismic source into a plurality of sector areas at imaging points according to a preset rule;
in each sector area, respectively determining a second PS wave sub CIP gather according to the P wave target offset velocity model and the target gamma model;
dividing the second PS-wave sub-CIP gather into a first offset PS sub-gather and a second offset PS sub-gather according to a preset offset threshold;
respectively obtaining a first converted wave model and a second converted wave model according to the first offset PS sub-track set and the second offset PS sub-track set;
and carrying out anisotropic correction on the uplink S wave on a second PS wave sub CIP gather corresponding to each fan-shaped area according to the first converted wave model and the second converted wave model, and superposing the corrected second PS wave sub CIP gather to obtain the PS wave target CIP gather.
8. The method of claim 7, wherein the determining a second PS-wave sub-CIP trace set from the P-wave target offset velocity model and the target γ model, respectively, comprises:
respectively generating an initial PS wave sub CIP gather according to the P wave target offset speed model and the target gamma model;
and performing time shift correction on the initial PS-wave sub-CIP gather to obtain the second PS-wave sub-CIP gather.
9. An apparatus for three-dimensional VSP imaging, comprising:
the first acquisition module is used for acquiring a P wave update speed model, wherein the P wave update speed model is obtained by updating a P wave initial speed model through a P wave isotropic offset speed;
the updating module is used for updating the P-wave anisotropic migration velocity of the P-wave updating velocity model to obtain a P-wave target migration velocity model, and the P-wave target migration velocity model is used for generating a PP-wave imaging profile according to a PP-wave CIP gather;
the second acquisition module is used for acquiring an initial gamma model, correcting the initial gamma model to obtain a target gamma model, wherein the gamma model is a PP wave T0 time domain P wave to S wave offset speed ratio model;
the imaging module is used for acquiring a PS wave target CIP gather according to the P wave target offset speed model and the target gamma model and generating a PS wave imaging section, wherein the PS wave target CIP gather is the PS wave CIP gather after the anisotropic effect of the downlink P wave and the uplink S wave is eliminated.
10. The apparatus of claim 9, wherein the apparatus further comprises:
and the separation module is used for carrying out fast and slow transverse wave separation on the PS wave imaging profile to obtain a target imaging profile.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103713323A (en) * | 2013-12-31 | 2014-04-09 | 孙赞东 | Omnibearing aeolotropy amplitude-preservation imaging and gather extracting method |
| CN105093310A (en) * | 2015-06-03 | 2015-11-25 | 北京多分量地震技术研究院 | Method for modeling migration velocity of converted waves |
| CN110780351A (en) * | 2018-07-31 | 2020-02-11 | 中国石油化工股份有限公司 | Longitudinal wave and converted wave prestack joint inversion method and system |
| CN111239832A (en) * | 2020-03-10 | 2020-06-05 | 中国地质大学（北京） | 3D3C-VSP imaging processing method, device and equipment |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6864890B2 (en) * | 2002-08-27 | 2005-03-08 | Comoco Phillips Company | Method of building and updating an anisotropic velocity model for depth imaging of seismic data |
-
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- 2023-03-09 CN CN202310257754.4A patent/CN116125535B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103713323A (en) * | 2013-12-31 | 2014-04-09 | 孙赞东 | Omnibearing aeolotropy amplitude-preservation imaging and gather extracting method |
| CN105093310A (en) * | 2015-06-03 | 2015-11-25 | 北京多分量地震技术研究院 | Method for modeling migration velocity of converted waves |
| CN110780351A (en) * | 2018-07-31 | 2020-02-11 | 中国石油化工股份有限公司 | Longitudinal wave and converted wave prestack joint inversion method and system |
| CN111239832A (en) * | 2020-03-10 | 2020-06-05 | 中国地质大学（北京） | 3D3C-VSP imaging processing method, device and equipment |
Non-Patent Citations (2)
| Title |
|---|
| Detection of Tectonically Deformed Coal Using Model-based joint Inversion of Multi-component Seismic Data;Lu Jun et al;ENERGIES;第11卷(第4期);全文 * |
| 横向各向同性介质地震波传播及逆时偏移成像方法研究;宋利伟;中国博士学位论文全文数据库;第基础科学辑卷(第03期);A011-122 * |
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