Well control seismic fast migration imaging method

Abstract

The application discloses a well control seismic fast migration imaging method, which comprises beam synthesis, beam propagation and beam imaging, and specifically comprises the following steps: (1) in the synthesis of the beam, first, the position of the local event is identified at the center position of the super-gather, then, the beam synthesis is completed by stacking along the slope direction of the event, and the seismic record is reversely calculated through the synthesized beam, and compared with the actual seismic record to perform quality control; (2) in the beam propagation, first, the ray tracing is performed along the corresponding slope direction from the shot point and the geophone position, then, the position of the imaging point is determined through the space and time criteria; (3) after the position of the imaging point of the beam is determined, the beam is unfolded around the imaging point according to the real part and the imaginary part of the Gaussian beam, and the beam imaging is performed. The application combines the imaging ability of the Gaussian beam migration and the imaging effect and the calculation efficiency of the fast migration while drilling based on the Gaussian beam are improved under the premise of well control.

Description

TECHNICAL FIELD

[0001] The present application relates to a well control seismic fast migration imaging method, belonging to the technical field of seismic exploration. BACKGROUND

[0002] Nowadays, as the exploration and development targets become more and more complex, a large number of directional drilling operations are needed, and the guidance of seismic data to the drilling trajectory is irreplaceable, and the prediction accuracy of seismic data for drilling design is higher and higher. Since the data of the ground seismic acquisition has no effective well data as a constraint, the drilling design data provided will have certain errors, and more accurate seismic data is needed for the drilling site to guide. How to quickly correct the velocity model based on the drilled strata data without affecting the drilling operation, and how to apply the fast migration imaging based on the drilled strata data at different stages of drilling are the problems to be solved at present.

[0003] At present, in the final imaging link, due to the different dependence on the accuracy of the velocity model, reverse time migration and Kirchhoff depth migration each account for half of the wall, and considering the calculation efficiency and imaging accuracy, Gaussian beam migration and one-way wave migration generally only play an auxiliary role. In addition, with the continuous improvement of the complexity of exploration targets, the "two wide and one high" seismic exploration technology has been widely developed, and the subsequent sharp increase in the amount of seismic data has brought great challenges to the migration imaging link. The fast beam migration based on the concept of beam migration not only has a great advantage in calculation efficiency compared with Kirchhoff depth migration, but also has the ability of multi-path imaging. The excellent imaging precision and quality of fast beam migration FBM imaging (especially in low signal-to-noise ratio and steep dip angle areas) can serve the updating of the velocity model and also can be used as the final imaging means.

[0004] Therefore, if the while-drilling fast imaging technology based on the FBM algorithm can achieve the purpose of fast migration imaging during drilling, solve the problem of fast migration imaging technology, and quickly, safely and accurately provide more accurate three-dimensional seismic comprehensive interpretation results in front of the drill bit and around the well for drilling engineers to guide the drilling trajectory adjustment, it will have broad prospects and very important significance. SUMMARY

[0005] The purpose of the present application is to provide a well control seismic fast migration imaging method, which can intuitively and quickly calculate the actual data imaging effect and realize quantitative calculation.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A well control seismic fast migration imaging method includes three steps of beam synthesis, beam propagation and beam imaging, and the specific steps are as follows:

[0008] (1) in the synthesis link of the beam, first identify the position of the local event in the center position of the super gather, then complete the beam synthesis along the slope direction of the event, and then calculate the seismic record through the synthesized beam, and compare with the actual seismic record to perform quality control;

[0009] (2) in the propagation link of the beam, first perform ray tracing along the corresponding slope direction from the shot point and the receiver position, and then determine the position of the imaging point through the space and time criteria;

[0010] (3) after determining the position of the imaging point of the beam, expand the beam near the imaging point according to the real part and the imaginary part of the Gaussian beam, and perform beam imaging.

[0011] As a further preferred embodiment of the present application, the space criterion is:

[0012] |s(A)-r(B)|<max_corr_dist

[0013] In the formula, s(A) represents the coordinates on the shot ray, r(B) represents the coordinates on the receiver ray, and max_corr_dist represents the maximum correlation distance.

[0014] As a further preferred embodiment of the present application, the time criterion is:

[0015] t s (M)+t r (M)≈event_time

[0016] In the formula, M represents the imaging point position, t s and t r respectively represent the travel time from the shot point and the receiver, and event_time represents the arrival time of the beam.

[0017] As a further preferred embodiment of the present application, after determining the position of the imaging point of the beam, the real part of the Gaussian beam is used to control the travel time, the imaginary part of the Gaussian beam is used to control the attenuation, the beam is expanded near the imaging point, and the beam imaging is performed.

[0018] The present application has the following advantages:

[0019] The fast beam migration FBM imaging algorithm of the present application can study the fast drilling imaging method based on the Gaussian beam in the acoustic medium based on the fast drilling imaging technology of the FBM algorithm, and in view of the characteristics that the fast drilling imaging only images in a limited space, the imaging effect and the calculation efficiency of the fast drilling imaging based on the Gaussian beam are improved under the premise of well control by combining the imaging ability of the Gaussian beam migration facing the target.

[0020] ​​Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the attendant drawings or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0022] Figure 1 is a schematic diagram of a fast migration process;

[0023] Figure 2 is a schematic diagram of beam synthesis;

[0024] Figure 3 is a schematic diagram of beam propagation;

[0025] Figure 4 is a schematic diagram of beam imaging;

[0026] Figure 5 is a diagram of super path selection;

[0027] Figure 6 is a velocity update diagram based on Well A VSP time-depth relationship calibration;

[0028] Figure 7 is a diagram of VSP depth and average velocity relationship;

[0029] Figure 8 is a velocity update diagram of grid tomography inversion method;

[0030] Figure 9 is a fast imaging effect diagram under velocity model update according to FBM algorithm. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0032] As shown in Figure 1 , a well control seismic fast migration imaging method includes three steps of beam synthesis, beam propagation and beam imaging, specifically as follows:

[0033] In step 1, in the composition of beam, first the position of local event (to time) is identified in the center of supergathers, then the composition of beam is completed by stacking along the slope direction of event, like Figure 2 Finally, the seismic record is calculated reversely from the composed beam, and compared with the actual seismic record to control the quality.

[0034] In step 2, in the propagation of beam, first the ray tracing is performed from the position of shot point and receiver point along the corresponding slope direction, then the position of imaging point is determined by space and time criteria, like Figure 3 .

[0035] The space criterion is:

[0036] |s(A)-r(B)|<max_corr_dist

[0037] Where s(A) represents the coordinate on the ray of shot point, r(B) represents the coordinate on the ray of receiver point, and max_corr_dist represents the maximum correlation distance.

[0038] The time criterion is:

[0039] t s (M)+t r (M)≈event_time

[0040] Where M represents the position of imaging point, t s and t r represent the travel time from shot point and receiver point respectively, and event_time represents the to time of beam. The position of imaging point is determined by finding the point closest to the to time of beam in the vicinity of the nearest position of two rays satisfying the conditions.

[0041] In step 3, after the position of imaging point of beam is determined, the beam is spread around the imaging point according to the real part (control travel time) and the imaginary part (control attenuation) of Gaussian beam, and the beam imaging is performed, like Figure 3 、 Figure 4 .

[0042] Refer to the velocity model update and iteration, rely on the grid tomography inversion method of gather flattening principle to update the speed, also introduce the stratum and structure constraint grid tomography and depth domain modeling method. On the basis of fully understanding the geology, logging of the work area, establish horizon surface, through the automatic picking of reflection wave, and carry out horizon and geological constraint grid tomography iteration under the constraint of geological dip angle field, obtain the residual velocity difference. Comprehensive utilization stratum background control velocity trend, fine grid, carry out high density grid tomography iteration under the constraint of structure and dip angle, at the same time, utilize sonic logging information constraint quality control, improve the accuracy of depth domain modeling. Can finally form the final result profile.

[0043] As Figures 5 to 9 shown, select the seismic data of X area, select Well A in X area to provide the updated velocity model; the imaging method of well control seismic fast migration of the present application is used to analyze and process the data of the region, and from the figure, it can be seen that the target effect is obvious.

[0044] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above examples do not limit the protection scope of the present application in any form, and any technical solutions obtained by equivalent replacement or the like fall within the protection scope of the present application.

[0045] The parts not involved in the present application are the same as or can be realized by the prior art.

Claims

1. A method of well control seismic fast migration imaging, characterized in that, The steps are as follows: (1) In the synthesis of beams, first, the position of the local event is identified at the center position of the supergathers, then the beam synthesis is completed by stacking along the slope direction of the event, and the seismic record is calculated reversely from the synthesized beam, and compared with the actual seismic record to control the quality; (2) In the propagation of beams, first, the ray tracing is performed from the shot point and the receiver point along the corresponding slope direction, and then the position of the imaging point is determined by the space criterion and the time criterion; The space criterion is: |s(A)-r(B)|<max_corr_dist In the formula, s(A) represents the coordinate on the shot ray, r(B) represents the coordinate on the receiver ray, and max_corr_dist represents the maximum correlation distance; The time criterion is: t s (M) + t r (M) ≈ event_time where M represents the imaging point position, t s and t r represent the travel times from the shot and receiver points, respectively, and event_time represents the arrival time of the beam. (3) After determining the imaging point position of the beam, the beam is expanded around the imaging point according to the real part and the imaginary part of the Gaussian beam, and beam imaging is performed; specifically, the real part of the Gaussian beam is used to control the travel time The imaginary part of the Gaussian beam is used to control the attenuation The beam is expanded around the imaging point, and beam imaging is performed.

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