CN109725354B

CN109725354B - Anisotropic speed modeling method and system

Info

Publication number: CN109725354B
Application number: CN201811382177.7A
Authority: CN
Inventors: 罗文山; 罗晓霞; 方勇; 袁燎; 高现俊; 张胜
Original assignee: China National Petroleum Corp; BGP Inc
Current assignee: China National Petroleum Corp; BGP Inc
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-07-10
Anticipated expiration: 2038-11-20
Also published as: CN109725354A

Abstract

The invention provides an anisotropic velocity modeling method and system. The anisotropic velocity modeling method comprises the steps of executing first iteration processing, and obtaining an initial inclined transverse isotropic velocity, an initial stratigraphic dip angle and an initial azimuth angle which correspond to a first prestack depth migration gather when the near offset distance is leveled; executing second iteration processing to obtain a second inclined transverse isotropic speed, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter and a second anisotropic parameter which correspond to the leveled near offset distance of the third prestack depth offset gather; and executing third iteration processing, obtaining a fourth anisotropic parameter corresponding to the leveled far offset distance of the fourth prestack depth offset gather, and obtaining an anisotropic velocity model according to the fourth anisotropic parameter, the third inclined transverse isotropic velocity, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter, so that the iteration period can be shortened, the offset imaging precision can be improved, and the error with actual data can be reduced.

Description

Anisotropic speed modeling method and system

Technical Field

The invention relates to the field of oil exploration, in particular to an anisotropic velocity modeling method and system.

Background

It has been generally agreed that the prestack depth migration imaging technique is a key technique for accurate imaging of complex structures. Since the assumption of anisotropy is closer to the actual subsurface medium than the assumption of isotropy, prestack depth migration imaging techniques based on the assumption of anisotropy are more common in industrial production applications. The key for determining the prestack depth migration imaging quality is the accuracy of an anisotropic velocity model, and the modeling of the anisotropic velocity model is the core of the prestack depth migration imaging processing of the mountain front complex high and steep structure.

At present, the modeling process of a TTI (oblique transverse isotropy) anisotropic velocity model commonly applied in industrial production has long iteration period and low iteration efficiency, and the established anisotropic velocity model has larger error with actual data.

Disclosure of Invention

The embodiments of the present invention mainly aim to provide an anisotropic velocity modeling method and system, so as to shorten an iteration cycle, improve iteration efficiency, reduce errors with actual data, and improve the accuracy of an anisotropic velocity model.

In order to achieve the above object, an embodiment of the present invention provides an anisotropic velocity modeling method, including:

executing a first iteration:

performing anisotropic prestack depth migration on the initial inclined transverse isotropic speed, the initial formation dip angle, the initial azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a first prestack depth migration gather;

judging whether the near offset distance of the first prestack depth offset gather is leveled or not; when the near offset of the first prestack depth offset gather is not corrected, carrying out iterative update on the initial inclination transverse isotropic speed, wherein the initial formation dip angle and the initial azimuth angle are updated along with the iterative update of the initial inclination transverse isotropic speed until the near offset of the first prestack depth offset gather obtained after carrying out anisotropic prestack depth offset by using the initial inclination transverse isotropic speed after the iterative update, the initial formation dip angle after the iterative update, the initial azimuth angle after the iterative update, the initial first anisotropic parameter and the initial second anisotropic parameter is leveled; when the near offset distance of the first prestack depth offset gather is leveled, ending the first iteration;

acquiring a first inclined transverse isotropic speed, a first stratigraphic dip angle and a first azimuth angle, wherein the first inclined transverse isotropic speed, the first stratigraphic dip angle and the first azimuth angle are respectively an initial inclined transverse isotropic speed, an initial stratigraphic dip angle and an initial azimuth angle corresponding to the leveled near offset distance of the first prestack depth offset gather;

and executing second iteration processing:

performing anisotropic prestack depth migration according to the first inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a second prestack depth migration gather;

calculating the isotropic speed according to the first inclined transverse isotropic speed and the initial first anisotropic parameter;

obtaining the interlayer thickness according to the first inclined transverse isotropic speed, the second prestack depth migration set and the isotropic speed;

calculating a first anisotropic parameter according to the interlayer thickness and the interlayer well layering thickness, and obtaining a second anisotropic parameter according to the first anisotropic parameter;

calculating a second inclined transverse isotropic speed according to the first anisotropic parameter and the isotropic speed;

performing anisotropic prestack depth migration on the second inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the first anisotropic parameter and the second anisotropic parameter to obtain a third prestack depth migration gather;

judging whether the near offset distance of the third prestack depth offset gather is leveled or not; when the near offset distance of the third pre-stack depth offset gather is not corrected, the second inclined transverse isotropic speed is updated in an iterative mode, the first stratum inclination angle and the first azimuth angle are updated along with the iterative updating of the second inclined transverse isotropic speed, the first inclined transverse isotropic speed is replaced by the second inclined transverse isotropic speed after the iterative updating, the first stratum inclination angle is replaced by the first stratum inclination angle after the iterative updating, the first azimuth angle is replaced by the first azimuth angle after the iterative updating, the initial first anisotropic parameter is replaced by the first anisotropic parameter, and the initial second anisotropic parameter is replaced by the second anisotropic parameter until the near offset distance of the third pre-stack depth offset gather is leveled; when the near offset distance of the third prestack depth offset gather is leveled, ending the second iteration;

acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; the third dip transverse isotropic speed, the second stratum inclination angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter are respectively a second dip transverse isotropic speed, a first stratum inclination angle, a first azimuth angle, a first anisotropic parameter and a second anisotropic parameter which correspond to the third pre-stack depth migration gather when the near offset distance is leveled;

and executing third iteration processing:

performing anisotropic prestack depth migration according to the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter to obtain a fourth prestack depth migration gather;

judging whether the far offset distance of the fourth prestack depth offset gather is leveled or not; when the far offset distance of the fourth prestack depth offset gather is not leveled, iteratively updating the fourth anisotropic parameter until the far offset distance of the fourth prestack depth offset gather obtained after anisotropic prestack depth offset is performed by using the fourth anisotropic parameter after iterative updating, the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter is leveled; when the far offset distance of the fourth prestack depth offset gather is leveled, the third iteration is finished;

and obtaining an anisotropic velocity model according to a fourth anisotropic parameter, a third inclined transverse isotropic velocity, a second stratum inclination angle, a second azimuth angle and a third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

An embodiment of the present invention further provides an anisotropic velocity modeling system, including:

a first iteration unit, configured to perform a first iteration process:

the first acquisition unit is used for acquiring a first inclined transverse isotropic speed, a first stratigraphic dip angle and a first azimuth angle, wherein the first inclined transverse isotropic speed, the first stratigraphic dip angle and the first azimuth angle are respectively an initial inclined transverse isotropic speed, an initial stratigraphic dip angle and an initial azimuth angle which correspond to the case that the near offset distance of the first prestack depth offset gather is leveled;

a second iteration unit, configured to perform a second iteration process:

the second acquisition unit is used for acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; the third dip transverse isotropic speed, the second stratum inclination angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter are respectively a second dip transverse isotropic speed, a first stratum inclination angle, a first azimuth angle, a first anisotropic parameter and a second anisotropic parameter which correspond to the third pre-stack depth migration gather when the near offset distance is leveled;

a third iteration unit, configured to perform a third iteration process:

and the anisotropic velocity model unit is used for obtaining an anisotropic velocity model according to a fourth anisotropic parameter, a third inclined transverse isotropic velocity, a second stratum inclination angle, a second azimuth angle and a third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

The embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and when the processor executes the computer program, the following steps are implemented:

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing:

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps:

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing:

The anisotropic velocity modeling method and the system of the embodiment of the invention firstly execute the first iteration processing to obtain the initial tilt transverse isotropic velocity, the initial stratigraphic dip angle and the initial azimuth angle corresponding to the leveled near offset distance of the first prestack depth migration gather, then execute the second iteration processing to obtain the second tilt transverse isotropic velocity, the first stratigraphic dip angle, the first azimuth angle, the first anisotropic parameter and the second anisotropic parameter corresponding to the leveled near offset distance of the third prestack depth migration gather, then execute the third iteration processing to obtain the fourth anisotropic parameter corresponding to the leveled far offset distance of the fourth prestack depth migration gather, and finally execute the third tilt transverse isotropic velocity, the second stratigraphic dip angle and the third iteration processing according to the fourth anisotropic parameter, the third tilt transverse isotropic velocity and the third anisotropic parameter corresponding to the leveled far offset distance of the fourth prestack depth migration gather, The second azimuth angle and the third anisotropic parameter are used for obtaining the anisotropic velocity model, so that the iteration period can be shortened, the iteration efficiency can be improved, the error between the second azimuth angle and the third anisotropic parameter and the actual data can be reduced, and the accuracy of the anisotropic velocity model can be improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a flow chart of a method of anisotropic velocity modeling in an embodiment of the present invention;

FIG. 2 is a flow chart of a method of anisotropic velocity modeling in another embodiment of the present invention;

FIG. 3 is a schematic illustration of initial tilt transverse isotropic velocity in an embodiment of the present invention;

FIG. 4 is a schematic illustration of an initial formation dip in an embodiment of the invention;

FIG. 5 is a schematic illustration of an initial azimuth angle in an embodiment of the present invention;

FIG. 6 is a schematic illustration of an initial first anisotropy parameter in an embodiment of the invention;

FIG. 7 is a schematic illustration of an initial second anisotropy parameter in an embodiment of the invention;

FIG. 8 is a schematic illustration of a third tilted transverse isotropic velocity in an embodiment of the present invention;

FIG. 9 is a schematic illustration of a second formation dip angle in an embodiment of the present invention;

FIG. 10 is a schematic illustration of a second azimuth angle in an embodiment of the present invention;

FIG. 11 is a schematic illustration of a third anisotropy parameter in an embodiment of the invention;

FIG. 12 is a diagram illustrating a fourth anisotropy parameter for a fourth prestack depth-offset gather when the far offsets of the fourth prestack depth-offset gather are leveled, in accordance with an embodiment of the present invention;

FIG. 13 is a schematic illustration of a prior art prestack depth migration gather in an embodiment of the present invention;

FIG. 14 is a schematic illustration of a fourth prestack depth migration gather in an embodiment of the present invention;

FIG. 15 is a block diagram of the structure of an anisotropic velocity modeling system in an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In view of the long iteration period and low iteration efficiency of the existing modeling process of the anisotropic velocity model, and the large error between the established anisotropic velocity model and actual data, the embodiment of the invention provides the anisotropic velocity modeling method, so as to shorten the iteration period, improve the iteration efficiency, reduce the error between the established anisotropic velocity model and the actual data, and improve the precision of the anisotropic velocity model. The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flow chart of a method for anisotropic velocity modeling in an embodiment of the present invention. As shown in fig. 1, the anisotropic velocity modeling method includes:

s101: executing a first iteration: performing anisotropic prestack depth migration on the initial inclined transverse isotropic speed, the initial formation dip angle, the initial azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a first prestack depth migration gather; judging whether the near offset distance of the first prestack depth offset gather is leveled or not; when the near offset of the first prestack depth offset gather is not corrected, carrying out iterative update on the initial inclination transverse isotropic speed, wherein the initial formation dip angle and the initial azimuth angle are updated along with the iterative update of the initial inclination transverse isotropic speed until the near offset of the first prestack depth offset gather obtained after carrying out anisotropic prestack depth offset by using the initial inclination transverse isotropic speed after the iterative update, the initial formation dip angle after the iterative update, the initial azimuth angle after the iterative update, the initial first anisotropic parameter and the initial second anisotropic parameter is leveled; the first iteration ends when the near offsets of the first prestack depth offset gather are leveled.

S102: and acquiring a first inclined transverse isotropic speed, a first stratigraphic dip angle and a first azimuth angle, wherein the first inclined transverse isotropic speed, the first stratigraphic dip angle and the first azimuth angle are respectively the initial inclined transverse isotropic speed, the initial stratigraphic dip angle and the initial azimuth angle corresponding to the leveled near offset distance of the first prestack depth offset gather.

S103: and executing second iteration processing: performing anisotropic prestack depth migration according to the first inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a second prestack depth migration gather; calculating the isotropic speed according to the first inclined transverse isotropic speed and the initial first anisotropic parameter; obtaining the interlayer thickness according to the first inclined transverse isotropic speed, the second prestack depth migration set and the isotropic speed; calculating a first anisotropic parameter according to the interlayer thickness and the interlayer well layering thickness, and obtaining a second anisotropic parameter according to the first anisotropic parameter; calculating a second inclined transverse isotropic speed according to the first anisotropic parameter and the isotropic speed; performing anisotropic prestack depth migration on the second inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the first anisotropic parameter and the second anisotropic parameter to obtain a third prestack depth migration gather; judging whether the near offset distance of the third prestack depth offset gather is leveled or not; when the near offset distance of the third pre-stack depth offset gather is not corrected, the second inclined transverse isotropic speed is updated in an iterative mode, the first stratum inclination angle and the first azimuth angle are updated along with the iterative updating of the second inclined transverse isotropic speed, the first inclined transverse isotropic speed is replaced by the second inclined transverse isotropic speed after the iterative updating, the first stratum inclination angle is replaced by the first stratum inclination angle after the iterative updating, the first azimuth angle is replaced by the first azimuth angle after the iterative updating, the initial first anisotropic parameter is replaced by the first anisotropic parameter, and the initial second anisotropic parameter is replaced by the second anisotropic parameter until the near offset distance of the third pre-stack depth offset gather is leveled; the second iteration ends when the near offset of the third prestack depth-offset gather is leveled.

S104: acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; the third dip transverse isotropic speed, the second formation dip angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter are respectively a second dip transverse isotropic speed, a first formation dip angle, a first azimuth angle, a first anisotropic parameter and a second anisotropic parameter which correspond to the third pre-stack depth migration gather when the near offset distance is leveled.

S105: and executing third iteration processing: performing anisotropic prestack depth migration according to the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter to obtain a fourth prestack depth migration gather; judging whether the far offset distance of the fourth prestack depth offset gather is leveled or not; when the far offset distance of the fourth prestack depth offset gather is not leveled, iteratively updating the fourth anisotropic parameter until the far offset distance of the fourth prestack depth offset gather obtained after anisotropic prestack depth offset is performed by using the fourth anisotropic parameter after iterative updating, the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter is leveled; the third iteration ends when the far offset of the fourth prestack depth offset gather is leveled.

S106: and obtaining an anisotropic velocity model according to a fourth anisotropic parameter, a third inclined transverse isotropic velocity, a second stratum inclination angle, a second azimuth angle and a third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

The execution subject of the anisotropic velocity modeling method shown in fig. 1 may be a computer. As can be seen from the process shown in fig. 1, the anisotropic velocity modeling method according to the embodiment of the present invention first performs a first iteration to obtain an initial tilted transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle corresponding to the case where the near offset distance of the first prestack depth migration gather is leveled, then performs a second iteration to obtain a second tilted transverse isotropic velocity, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to the case where the near offset distance of the third prestack depth migration gather is leveled, then performs a third iteration to obtain a fourth anisotropic parameter corresponding to the case where the far offset distance of the fourth prestack depth migration gather is leveled, and finally performs a third iteration to obtain a fourth anisotropic parameter, a third tilted transverse isotropic velocity parameter, and a third anisotropic parameter corresponding to the case where the far offset distance of the fourth prestack depth migration gather is leveled according to the fourth anisotropic parameter, the third tilted transverse isotropic velocity, which correspond to the case where the far offset distance of the fourth prest, The second formation inclination angle, the second azimuth angle and the third anisotropic parameter are used for obtaining the anisotropic velocity model, so that the iteration period can be shortened, the iteration efficiency can be improved, the error with actual data can be reduced, and the accuracy of the anisotropic velocity model can be improved.

FIG. 2 is a flow chart of a method of anisotropic velocity modeling in another embodiment of the present invention. As shown in fig. 2, before executing S101, the method further includes:

s201: and performing first arrival chromatographic inversion on the micro-logging data, and establishing a near-surface velocity model.

S202: and establishing a time domain root mean square speed model.

Wherein the time domain root mean square velocity model may be established using conventional pre-stack time migration.

S203: and converting the time domain root mean square velocity model into a depth domain layer velocity model according to a constrained velocity inversion method.

The time domain root mean square velocity model can also be converted into the depth domain layer velocity model through the dix formula.

S204: and carrying out comprehensive constraint on the depth domain layer velocity model according to the micro-logging data to obtain a middle-deep layer initial layer velocity model.

S205: and splicing the near-surface velocity model and the middle-deep layer initial layer velocity model to obtain the initial inclined transverse isotropic velocity.

During splicing, the high-speed top surface obtained in the chromatographic inversion process of S101 moves downwards to a position with a small difference between the near-surface velocity model and the middle-deep layer initial layer velocity model to serve as a splicing surface, the near-surface velocity model above the splicing surface is guaranteed to be credible, a smooth time window is determined during matching and splicing, the velocity in the time window is subjected to smoothing and interpolation processing, the low-frequency background of the velocity is kept, the velocity mutation is eliminated, and a fluctuating-surface isotropic velocity model is established to serve as the initial inclined transverse isotropic velocity.

S206: and carrying out isotropic prestack depth migration on the initial inclined transverse isotropic speed to obtain an initial formation inclination angle and an initial azimuth angle.

In an embodiment, the initial first anisotropy parameter is equal to the initial second anisotropy parameter, and the initial tilt transverse isotropy velocity or the fourth anisotropy parameter may be iteratively updated by a grid chromatography method, and the anisotropic prestack depth migration is TTI anisotropic kirchhoff integration prestack depth migration.

In an embodiment, obtaining the interlayer thickness according to the first oblique transverse isotropic velocity, the second pre-stack depth migration track set, and the isotropic velocity specifically includes: obtaining depth migration superposition data according to the second prestack depth migration gather; scaling the depth offset stacked data to a time domain according to the first tilted transverse isotropic velocity; and obtaining the interlayer thickness according to the isotropic speed and the depth offset superposition data from the proportion to the time domain.

In one embodiment, the isotropic velocity is calculated by the following formula:

where V is the isotropic velocity and Vp0 is the first tilted transverse isotropic velocity, which is the initial first anisotropy parameter.

In one embodiment, the first anisotropy parameter is calculated by the following equation:

where,' is the first anisotropy parameter, Δ Zs is the thickness between layers, and Δ Zw is the thickness of the well layer between layers.

In one embodiment, the second tilt transverse isotropy velocity is calculated by the following formula:

where Vp0 'is the second tilt transverse isotropic velocity, V is the isotropic velocity, and' is the first anisotropy parameter.

Wherein, the first anisotropic parameter' is the updated initial first anisotropic parameter, and the third anisotropic parameter is the updated first anisotropic parameter; the second anisotropic parameter is an updated initial second anisotropic parameter, and the fourth anisotropic parameter is an updated second anisotropic parameter.

The specific process of the embodiment of the invention is as follows:

1. and performing first arrival chromatographic inversion on the micro-logging data, and establishing a near-surface velocity model.

2. Establishing a time domain root-mean-square speed model by utilizing conventional pre-stack time migration; converting the time domain root mean square velocity model into a depth domain layer velocity model according to a constrained velocity inversion method or a Dix formula; and carrying out comprehensive constraint on the depth domain layer velocity model according to the micro-logging data to obtain a middle-deep layer initial layer velocity model.

3. And splicing the near-surface velocity model and the middle-deep layer initial layer velocity model to obtain the initial inclined transverse isotropic velocity. FIG. 3 is a graphical representation of initial tilt transverse isotropic velocity in an embodiment of the present invention. As shown in FIG. 3, the horizontal axis is the dot number along the direction of the survey line, and the unit is the track; the vertical axis is depth in meters. During splicing, the high-speed top surface obtained in the chromatographic inversion process in the step 1 is moved downwards to a position with a small difference between the near-surface velocity model and the intermediate-deep layer initial layer velocity model to serve as a splicing surface, the near-surface velocity model above the splicing surface is guaranteed to be credible, a smooth time window is determined during matching and splicing, the velocity in the time window is subjected to smoothing and interpolation processing, the low-frequency background of the velocity is kept, the velocity mutation is eliminated, and a fluctuating surface isotropic velocity model is established to serve as the initial inclined transverse isotropic velocity.

4. And carrying out isotropic prestack depth migration on the initial inclined transverse isotropic speed to obtain an initial formation inclination angle and an initial azimuth angle. FIG. 4 is a schematic illustration of initial formation dip in an embodiment of the invention. Fig. 5 is a schematic diagram of an initial azimuth angle in an embodiment of the present invention. As shown in fig. 4 and 5, the horizontal axes in fig. 4 and 5 are point numbers along the measuring line direction, and the unit is a track; the vertical axis is depth in meters. The isotropic prestack depth migration is isotropic kirchhoff integration prestack depth migration, and is required to meet certain grid density, so that the obtained initial formation dip angle and initial azimuth angle can be matched with a migration result.

5. An initial first anisotropy parameter and an initial second anisotropy parameter are set. FIG. 6 is a schematic illustration of an initial first anisotropy parameter in an embodiment of the invention. FIG. 7 is a schematic illustration of an initial second anisotropy parameter in an embodiment of the invention. As shown in fig. 6 and 7, the horizontal axes in fig. 6 and 7 are point numbers along the measuring line direction, and the unit is a track; the vertical axis is depth in meters.

6. Executing a first iteration: performing anisotropic prestack depth migration on the initial inclined transverse isotropic speed, the initial formation dip angle, the initial azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a first prestack depth migration gather; judging whether the near offset distance of the first prestack depth offset gather is leveled or not; when the near offset distance of the first prestack depth migration gather is not corrected, the initial dip transverse isotropic speed is updated in an iteration mode through a grid chromatography method, at the moment, the initial formation dip angle and the initial azimuth angle are updated along with the iteration update of the initial dip transverse isotropic speed, and the near offset distance of the first prestack depth migration gather is obtained after the initial dip transverse isotropic speed after the iteration update, the initial formation dip angle after the iteration update, the initial azimuth angle after the iteration update, the initial first anisotropic parameter and the initial second anisotropic parameter are used for conducting anisotropic prestack depth migration; the first iteration ends when the near offsets of the first prestack depth offset gather are leveled.

The first prestack depth migration overlay data can be obtained through the first prestack depth migration gather, and then the latest initial stratigraphic dip angle and the latest initial azimuth angle are extracted by utilizing the first prestack depth migration overlay data. Compared with isotropic prestack depth migration, the anisotropic prestack depth migration introduces a stratigraphic dip angle and an azimuth angle in an iteration process, and can obtain more accurate inclined transverse isotropic speed aiming at a complex high and steep construction region, so that the spatial homing of the complex high and steep construction region is more accurate. In this step, the initial dip transverse isotropic velocity, the initial formation dip angle and the initial azimuth angle are updated, and the initial first anisotropic parameter and the initial second anisotropic parameter are kept unchanged.

7. And acquiring a first inclined transverse isotropic speed, a first stratigraphic dip angle and a first azimuth angle, wherein the first inclined transverse isotropic speed, the first stratigraphic dip angle and the first azimuth angle are respectively the initial inclined transverse isotropic speed, the initial stratigraphic dip angle and the initial azimuth angle corresponding to the leveled near offset distance of the first prestack depth offset gather.

8. And executing second iteration processing:

(1) and performing anisotropic prestack depth migration according to the first inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a second prestack depth migration gather.

(2) The isotropic velocity is calculated from the first tilted transverse isotropic velocity and the initial first anisotropy parameter. In specific implementation, the isotropic speed can be calculated by the following formula:

(3) Obtaining depth migration superposition data according to the second prestack depth migration gather; scaling the depth offset stacked data to a time domain according to the first tilted transverse isotropic velocity; and rescaling the depth offset superposition data scaled to the time domain back to the depth domain according to the isotropic speed to obtain the interlayer thickness. Compared with the depth migration superposition data directly obtained through isotropic prestack depth migration, the method has more accurate transverse spatial position at the part with large stratigraphic dip angle, so that the obtained interlayer thickness is more accurate.

(4) And calculating a first anisotropic parameter according to the interlayer thickness and the interlayer well delamination thickness, and assigning the first anisotropic parameter to a second anisotropic parameter. The first anisotropic parameter is a parameter influencing the speed of the longitudinal wave in the nearly vertical direction, the second anisotropic parameter is a parameter representing the anisotropic strength of the longitudinal wave, and the larger the second anisotropic parameter is, the larger the longitudinal wave anisotropy of the medium is.

In specific implementation, the first anisotropy parameter may be calculated by the following formula:

(5) And calculating a second tilt transverse isotropy velocity according to the first anisotropy parameter and the isotropy velocity. In specific implementation, the second tilt transverse isotropy velocity can be calculated by the following formula:

(6) And performing anisotropic prestack depth migration on the second inclined transverse isotropic speed, the first stratum inclination angle, the first azimuth angle, the first anisotropic parameter and the second anisotropic parameter to obtain a third prestack depth migration gather.

(7) Judging whether the near offset distance of the third prestack depth offset gather is leveled or not; when the near offset distance of the third pre-stack depth offset gather is not corrected, the second inclined transverse isotropic speed is updated through a grid chromatography method, at the moment, the first formation dip angle and the first azimuth angle are updated along with the iterative update of the second inclined transverse isotropic speed, the first inclined transverse isotropic speed is replaced by the second inclined transverse isotropic speed after the iterative update, the first formation dip angle after the iterative update is replaced by the first formation dip angle, the first azimuth angle after the iterative update is replaced by the first azimuth angle, the initial first anisotropic parameter is replaced by the first anisotropic parameter, the initial second anisotropic parameter is replaced by the second anisotropic parameter, and the steps (1) to (7) are repeatedly executed until the near offset distance of the third pre-stack depth offset gather is leveled; the second iteration ends when the near offset of the third prestack depth-offset gather is leveled.

9. Acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; the third dip transverse isotropic speed, the second formation dip angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter are respectively a second dip transverse isotropic speed, a first formation dip angle, a first azimuth angle, a first anisotropic parameter and a second anisotropic parameter which correspond to the third pre-stack depth migration gather when the near offset distance is leveled.

10. And executing third iteration processing: performing anisotropic prestack depth migration according to the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle, the third anisotropic parameter and the fourth anisotropic parameter to obtain a fourth prestack depth migration gather; judging whether the far offset distance of the fourth prestack depth offset gather is leveled or not; when the far offset distance of the fourth prestack depth offset gather is not leveled, iteratively updating the fourth anisotropic parameter by a grid chromatography method until the far offset distance of the fourth prestack depth offset gather is leveled after anisotropic prestack depth offset is performed by using the iteratively updated fourth anisotropic parameter, the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter; the third iteration ends when the far offset of the fourth prestack depth offset gather is leveled.

FIG. 8 is a schematic representation of a third tilted transverse isotropic velocity in an embodiment of the present invention. FIG. 9 is a schematic illustration of a second formation dip angle in an embodiment of the present invention. Fig. 10 is a schematic view of a second azimuth angle in an embodiment of the present invention. FIG. 11 is a schematic illustration of a third anisotropy parameter in an embodiment of the invention. FIG. 12 is a diagram illustrating a fourth anisotropy parameter for a fourth prestack depth-offset gather when the far offsets of the fourth prestack depth-offset gather are leveled, according to an embodiment of the invention. As shown in fig. 8 to 12, the horizontal axes in fig. 8 to 12 are all dot numbers along the direction of the measuring line, and the unit is a track; the vertical axis is depth in meters.

FIG. 13 is a schematic diagram of a prestack depth migration gather of the prior art in the embodiment of the present invention, FIG. 14 is a schematic diagram of a fourth prestack depth migration gather of the embodiment of the present invention, as shown in FIGS. 13 and 14, the horizontal axes in FIGS. 13 and 14 are point numbers along the direction of a measuring line, and the vertical axes are depths, and the K L204 in the diagram is the well point position, the E1-2km14628 represents that the E1-2km1 formation is 4628m in true depth, and the E1-2km 45095 represents that the E1-2km4 formation is 5095m in true depth.

11. And obtaining an anisotropic velocity model according to a fourth anisotropic parameter, a third inclined transverse isotropic velocity, a second stratum inclination angle, a second azimuth angle and a third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

To sum up, the anisotropic velocity modeling method according to the embodiment of the present invention first performs a first iteration to obtain an initial tilt transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle corresponding to a case where a near offset distance of a first prestack depth migration gather is leveled, then performs a second iteration to obtain a second tilt transverse isotropic velocity, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to a case where a near offset distance of a third prestack depth migration gather is leveled, then performs a third iteration to obtain a fourth anisotropic parameter corresponding to a case where a far offset distance of a fourth prestack depth migration gather is leveled, and finally performs a fourth anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, and a corresponding to a case where a far offset distance of the fourth prestack depth migration gather is leveled according to a fourth anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, and a corresponding to a case where a far offset distance of the fourth prestack depth, The second azimuth angle and the third anisotropic parameter are used for obtaining the anisotropic velocity model, so that the iteration period can be shortened, the iteration efficiency can be improved, the error between the second azimuth angle and the third anisotropic parameter and the actual data can be reduced, and the accuracy of the anisotropic velocity model can be improved.

Based on the same inventive concept, the embodiment of the invention also provides an anisotropic velocity modeling system, and as the principle of solving the problem of the system is similar to that of the anisotropic velocity modeling method, the implementation of the system can refer to the implementation of the method, and repeated parts are not described again.

FIG. 15 is a block diagram of the structure of an anisotropic velocity modeling system in an embodiment of the invention. As shown in fig. 15, the anisotropic velocity modeling system includes:

a first iteration unit, configured to perform a first iteration process:

a second iteration unit, configured to perform a second iteration process:

a third iteration unit, configured to perform a third iteration process:

In one embodiment, the method further comprises the following steps:

the near-surface velocity model unit is used for carrying out first arrival chromatography inversion on the micro-logging data and establishing a near-surface velocity model;

the time domain root-mean-square speed model unit is used for establishing a time domain root-mean-square speed model;

the depth domain layer velocity model unit is used for converting the time domain root mean square velocity model into a depth domain layer velocity model according to a constrained velocity inversion method;

the middle-deep layer initial layer velocity model unit is used for carrying out comprehensive constraint on the depth domain layer velocity model according to the micro-logging data to obtain a middle-deep layer initial layer velocity model;

the splicing unit is used for splicing the near-surface velocity model and the middle-deep layer initial layer velocity model to obtain an initial inclined transverse isotropic velocity;

and the anisotropic prestack depth migration unit is used for carrying out isotropic prestack depth migration on the initial inclined transverse isotropic speed to obtain an initial formation inclination angle and an initial azimuth angle.

In one embodiment, the second iteration unit is specifically configured to:

obtaining depth migration superposition data according to the second prestack depth migration gather;

scaling the depth offset stacked data to a time domain according to the first tilted transverse isotropic velocity;

and obtaining the interlayer thickness according to the isotropic speed and the depth offset superposition data from the proportion to the time domain.

In one embodiment, the isotropic velocity is calculated by the following equation:

In one embodiment, the second tilt transverse isotropy velocity is calculated by the following equation:

To sum up, the anisotropic velocity modeling system according to the embodiment of the present invention first performs a first iteration to obtain an initial tilt transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle corresponding to the case where the near offset distance of the first prestack depth migration gather is leveled, then performs a second iteration to obtain a second tilt transverse isotropic velocity, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to the case where the near offset distance of the third prestack depth migration gather is leveled, then performs a third iteration to obtain a fourth anisotropic parameter corresponding to the case where the far offset distance of the fourth prestack depth migration gather is leveled, and finally performs a fourth anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, and a corresponding to the case where the far offset distance of the fourth prestack depth migration gather is leveled according to the fourth anisotropic parameter, the third tilt transverse isotropic velocity, the second stratigraphic dip angle, and the third anisotropic parameter corresponding to the case where the far offset distance of the fourth, The second azimuth angle and the third anisotropic parameter are used for obtaining the anisotropic velocity model, so that the iteration period can be shortened, the iteration efficiency can be improved, the error between the second azimuth angle and the third anisotropic parameter and the actual data can be reduced, and the accuracy of the anisotropic velocity model can be improved.

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing:

To sum up, the computer device of the embodiment of the present invention first performs a first iteration to obtain an initial tilt transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle corresponding to a case where a near offset distance of a first prestack depth migration gather is leveled, then performs a second iteration to obtain a second tilt transverse isotropic velocity, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to a case where a near offset distance of a third prestack depth migration gather is leveled, then performs a third iteration to obtain a fourth anisotropic parameter corresponding to a case where a far offset distance of a fourth prestack depth migration gather is leveled, and finally obtains an anisotropic velocity model according to a fourth anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, a second azimuth angle, and a third anisotropic parameter corresponding to a case where a far offset distance of the fourth prestack depth migration gather is leveled, the method can shorten the iteration period, improve the iteration efficiency, reduce the error with actual data and improve the accuracy of the anisotropic velocity model.

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing:

To sum up, the computer-readable storage medium according to the embodiment of the present invention first performs a first iteration to obtain an initial tilt transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle corresponding to a case where a near offset distance of a first prestack depth migration gather is leveled, then performs a second iteration to obtain a second tilt transverse isotropic velocity, a first stratigraphic dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to a case where a near offset distance of a third prestack depth migration gather is leveled, then performs a third iteration to obtain a fourth anisotropic parameter corresponding to a case where a far offset distance of a fourth prestack depth migration gather is leveled, and finally performs a third iteration to obtain a third anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, and a third anisotropic parameter corresponding to a case where a far offset distance of the fourth prestack depth migration gather is leveled according to a fourth anisotropic parameter, a third tilt transverse isotropic velocity, a second stratigraphic dip angle, and a third anisotropic parameter corresponding to a, The second azimuth angle and the third anisotropic parameter are used for obtaining the anisotropic velocity model, so that the iteration period can be shortened, the iteration efficiency can be improved, the error between the second azimuth angle and the third anisotropic parameter and the actual data can be reduced, and the accuracy of the anisotropic velocity model can be improved.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method of modeling anisotropic velocity, comprising:

executing a first iteration:

judging whether the near offset distance of the first prestack depth offset gather is leveled or not; when the near offset of the first prestack depth migration gather is not corrected, iteratively updating the initial dip transverse isotropic speed, wherein the initial formation dip angle and the initial azimuth angle are updated along with the iterative updating of the initial dip transverse isotropic speed until after anisotropic prestack depth migration is performed by using the iteratively updated initial dip transverse isotropic speed, the iteratively updated initial formation dip angle, the iteratively updated initial azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter, a first prestack depth migration gather with the leveled near offset is obtained; when the near offset of the first prestack depth offset gather is leveled, ending the first iteration;

acquiring a first inclined transverse isotropic speed, a first stratigraphic dip and a first azimuth, wherein the first inclined transverse isotropic speed, the first stratigraphic dip and the first azimuth are respectively an initial inclined transverse isotropic speed, an initial stratigraphic dip and an initial azimuth corresponding to the case that the near offset distance of the first prestack depth offset gather is leveled;

and executing second iteration processing:

performing anisotropic prestack depth migration according to the first inclined transverse isotropic speed, the first formation dip angle, the first azimuth angle, the initial first anisotropic parameter and the initial second anisotropic parameter to obtain a second prestack depth migration gather;

calculating an isotropic speed according to the first inclined transverse isotropic speed and the initial first anisotropic parameter;

obtaining the thickness of the seismic layer according to the first inclined transverse isotropic speed, the second prestack depth migration trace set and the isotropic speed;

calculating a first anisotropic parameter according to the seismic interlayer thickness and the interlayer well layered thickness, and obtaining a second anisotropic parameter according to the first anisotropic parameter;

calculating a second tilt transverse isotropy velocity according to the first anisotropy parameter and the isotropy velocity;

performing anisotropic prestack depth migration on the second inclined transverse isotropic speed, the first formation dip angle, the first azimuth angle, the first anisotropic parameter and the second anisotropic parameter to obtain a third prestack depth migration gather;

judging whether the near offset distance of the third prestack depth offset gather is leveled or not; when the near offset distance of the third pre-stack depth offset gather is not corrected, iteratively updating the second inclined transverse isotropic speed, wherein the first formation dip angle and the first azimuth angle are updated along with the iterative updating of the second inclined transverse isotropic speed, the first inclined transverse isotropic speed is replaced by the second inclined transverse isotropic speed after the iterative updating, the first formation dip angle is replaced by the first formation dip angle after the iterative updating, the first azimuth angle is replaced by the first azimuth angle after the iterative updating, the initial first anisotropic parameter is replaced by the first anisotropic parameter, the initial second anisotropic parameter is replaced by the second anisotropic parameter, and the third pre-stack depth offset gather with the leveled near offset distance is obtained; when the near offset of the third prestack depth offset gather is leveled, ending the second iteration;

acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; wherein the third tilted transverse isotropic velocity, the second formation dip angle, the second azimuth angle, the third anisotropic parameter, and the fourth anisotropic parameter are respectively a second tilted transverse isotropic velocity, a first formation dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to the third pre-stack depth migration gather when the near offset distance is leveled;

and executing third iteration processing:

judging whether the far offset distance of the fourth prestack depth offset gather is leveled; when the far offset distance of the fourth prestack depth offset gather is not corrected, iteratively updating the fourth anisotropic parameter until anisotropic prestack depth offset is performed by using the iteratively updated fourth anisotropic parameter, the third inclined transverse isotropic speed, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter, so as to obtain a fourth prestack depth offset gather of which the far offset distance is leveled; when the far offset of the fourth prestack depth offset gather is leveled, ending the third iteration;

and obtaining an anisotropic velocity model according to a fourth anisotropic parameter, the third inclined transverse isotropic velocity, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

2. The method of claim 1, wherein prior to performing the first iteration, further comprising:

carrying out first arrival chromatographic inversion on the micro-logging data, and establishing a near-surface velocity model;

establishing a time domain root-mean-square speed model;

converting the time domain root mean square velocity model into a depth domain layer velocity model according to a constrained velocity inversion method;

comprehensively constraining the depth domain layer velocity model according to the micro-logging data to obtain a middle-deep layer initial layer velocity model;

splicing the near-surface velocity model and the intermediate-deep layer initial layer velocity model to obtain the initial inclined transverse isotropic velocity;

and carrying out isotropic prestack depth migration on the initial inclined transverse isotropic speed to obtain an initial formation inclination angle and an initial azimuth angle.

3. The method for modeling anisotropic velocity according to claim 1, wherein obtaining a seismic interval thickness from the first oblique transverse isotropic velocity, the second prestack depth migration trace set, and the isotropic velocity specifically comprises:

obtaining depth migration stacking data according to the second prestack depth migration gather;

scaling the depth migration overlay data to a time domain according to the first tilted transverse isotropic velocity;

4. The method of claim 1, wherein the isotropic velocity is calculated by the formula:

5. The method of claim 1, wherein the first anisotropy parameter is calculated by the formula:

6. The method of anisotropic velocity modeling according to claim 1, wherein the second tilt transverse isotropic velocity is calculated by the following formula:

7. An anisotropic velocity modeling system, comprising:

a first iteration unit, configured to perform a first iteration process:

a first obtaining unit, configured to obtain a first tilted transverse isotropic velocity, a first stratigraphic dip angle, and a first azimuth angle, where the first tilted transverse isotropic velocity, the first stratigraphic dip angle, and the first azimuth angle are an initial tilted transverse isotropic velocity, an initial stratigraphic dip angle, and an initial azimuth angle that correspond to a case where a near offset distance of the first pre-stack depth offset gather is leveled, respectively;

a second iteration unit, configured to perform a second iteration process:

the second acquisition unit is used for acquiring a third inclination transverse isotropic speed, a second stratum inclination angle, a second azimuth angle, a third anisotropic parameter and a fourth anisotropic parameter; wherein the third tilted transverse isotropic velocity, the second formation dip angle, the second azimuth angle, the third anisotropic parameter, and the fourth anisotropic parameter are respectively a second tilted transverse isotropic velocity, a first formation dip angle, a first azimuth angle, a first anisotropic parameter, and a second anisotropic parameter corresponding to the third pre-stack depth migration gather when the near offset distance is leveled;

a third iteration unit, configured to perform a third iteration process:

and the anisotropic velocity model unit is used for obtaining an anisotropic velocity model according to a fourth anisotropic parameter, the third inclined transverse isotropic velocity, the second stratum inclination angle, the second azimuth angle and the third anisotropic parameter which correspond to the leveled far offset distance of the fourth prestack depth offset gather.

8. The anisotropic velocity modeling system of claim 7, further comprising:

the splicing unit is used for splicing the near-surface velocity model and the intermediate-deep layer initial layer velocity model to obtain the initial inclined transverse isotropic velocity;

9. The anisotropic velocity modeling system of claim 7, wherein the second iteration unit is specifically configured to:

10. The anisotropic velocity modeling system of claim 7, wherein the isotropic velocity is calculated by the formula:

11. The anisotropic velocity modeling system of claim 7, wherein the first anisotropy parameter is calculated by the formula:

12. The anisotropic velocity modeling system of claim 7, wherein the second tilted transverse isotropic velocity is calculated by the formula:

13. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the computer program implements the steps of:

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing:

14. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of:

executing a first iteration:

and executing second iteration processing:

and executing third iteration processing: