CN-115826038-B - VTI medium accompanying state method travel time multi-parameter tomography method and system

CN115826038BCN 115826038 BCN115826038 BCN 115826038BCN-115826038-B

Abstract

The invention relates to a VTI medium accompanying state method travel time multi-parameter tomography method and system, which comprises 1) obtaining the observation first arrival travel time of original seismic data, determining an initial speed and anisotropy parameter model and an observation system file, 2) calculating the theoretical travel time field of a single gun and determining a single gun objective function and an accompanying field of the single gun, 3) calculating the single gun multi-parameter gradient of a VTI medium, 4) calculating a single gun precondition illumination compensation operator, 5) obtaining a VTI multi-parameter tomography result according to the objective function, the multi-parameter gradient and the precondition illumination compensation operator of all guns, judging whether the VTI multi-parameter tomography result meets the requirement, outputting the VTI multi-parameter tomography result if the VTI multi-parameter tomography result meets the requirement, otherwise, entering step 6) obtaining an updated speed and anisotropy parameter model, and being widely applied to the near-surface anisotropy parameter modeling field.

Inventors

DU XIANGDONG
ZHANG HONGLIANG
ZHENG YING
Bao Tiezhao
WANG JIANHUA
NIU CONG
SUN WENBO
YE YUNFEI
LIU ZHIPENG
WANG QINGZHEN
CHEN JIANJUN
LING YUN

Assignees

中海石油(中国)有限公司
中海石油（中国）有限公司北京研究中心

Dates

Publication Date: 20260512
Application Date: 20221108

Claims (8)

1. A VTI medium is accompanied by the multi-parameter chromatography imaging method of state method travel time, characterized by comprising: 1) Acquiring the initial arrival travel time of the original seismic data, and determining an initial speed and anisotropic parameter model and an observation system file; 2) Calculating a theoretical travel time field of the single cannon according to the speed and the anisotropic parameter model, and determining a single cannon objective function and an accompanying field of the single cannon according to the first arrival travel time based on an observation system file; 3) Calculating a single-gun multi-parameter gradient of the VTI medium according to the speed and the anisotropic parameter model; 4) Calculating a preconditioning illumination compensation operator of the single shot according to the first arrival travel time of observation and the theoretical travel time field of the single shot; 5) Obtaining a VTI multi-parameter tomography result according to the objective function, multi-parameter gradient and preconditioning illumination compensation operator of all the cannons, judging whether the VTI multi-parameter tomography result meets the requirement, and outputting the VTI multi-parameter tomography result if the VTI multi-parameter tomography result meets the requirement, otherwise, entering the step 6); 6) Obtaining updated speed and anisotropic parameter models according to the accompanying fields of single cannons and the preconditioning illumination compensation operators of all cannons, and entering the step 2) until the VTI multi-parameter tomography result meets the requirements; in the step 2), according to the speed and the anisotropic parameter model, calculating a theoretical travel time field of the single gun, and based on an observation system file, determining a single gun objective function and an accompanying field of the single gun according to the observation first arrival travel time, wherein the method comprises the following steps: calculating a theoretical travel time field of a single gun according to the speed and the anisotropic parameter model by adopting a rapid scanning algorithm; determining a single-shot target function according to the first arrival travel time and the theoretical travel time field of the single shot based on an observation system file; Determining an accompanying field of the single cannon according to the observed first arrival travel time and the theoretical travel time field of the single cannon; Based on the observation system file, determining a single shot target function according to the observation first arrival travel time and the theoretical travel time field of the single shot, comprising: calculating the travel time difference between the observed first arrival travel time and the theoretical travel time field of the single cannon; Based on the observation system file, obtaining a single-shot target function according to the travel time difference of the single-shot : Wherein, the Represent the first The positions of the detection points; Representing a calculation region Any position in the interior, use Function of Control area Calculating an objective function at the inner wave detection point; Is the first arrival travel time calculated theoretically.
2. The VTI medium-associated state-method travel-time multiparameter tomography method of claim 1, wherein the theoretical travel-time field of a single shot Based on the following equation: Wherein, the Is a control equation; And Respectively the abscissa and the ordinate of the underground space point; is the speed; And Is Thomsen anisotropic parameter.
3. The VTI medium-accompanied state method travel time multi-parameter tomography method of claim 1, wherein the following accompanying state equation is adopted to back project the travel time difference of a single shot into the underground multi-parameter model space to obtain the accompanying field of the single shot : Wherein, the For accompanying field Is a coefficient matrix of (a).
4. The VTI medium-associated state-method travel-time multi-parameter tomography method of claim 1, wherein in step 4), the single-shot preconditioned illumination compensation operator is calculated according to the observed first arrival travel-time and the theoretical travel-time field of the single shot, comprising: setting the travel time difference of a single gun as a fixed constant; Initializing an accompanying field of the position of the wave detection point based on a fixed constant, and injecting a counter-transmission source; And (3) transmitting the accompanying fields at the positions of the detection points to the underground model by adopting a rapid scanning method, scanning in different directions, and calculating the accompanying fields at each point of the whole underground model space to obtain a single-gun preconditioned illumination compensation operator.
5. The VTI medium concomitant state method time-lapse multi-parameter tomography method of claim 1, wherein in the step 6), an updated velocity and anisotropy parameter model is obtained according to a concomitant field of a single gun and a preconditioned illumination compensation operator of all guns, and the step 2) is entered until the VTI multi-parameter tomography result meets the requirements, comprising: according to the accompanying field of a single gun and the precondition illumination compensation operators of all guns, carrying out illumination compensation on the original multi-parameter gradient to obtain an illumination compensated gradient; and (3) obtaining an updated speed and anisotropy parameter model according to the gradient after illumination compensation, and entering the step (2) until the VTI multi-parameter tomography result meets the requirement, and obtaining a final VTI multi-parameter tomography result.
6. A VTI media-accompanied state-method time-of-flight multiparameter tomography system comprising: The data acquisition module is used for acquiring the initial arrival time of the original seismic data, and determining an initial speed and anisotropy parameter model and an observation system file; The theoretical travel time field calculation module is used for calculating the theoretical travel time field of the single cannon according to the speed and the anisotropic parameter model, and determining a single cannon objective function and an accompanying field of the single cannon according to the first arrival travel time based on the observation system file; the gradient calculation module is used for calculating single-gun multi-parameter gradients of the VTI medium according to the speed and the anisotropic parameter model; the illumination compensation operator calculation module is used for calculating a preconditioned illumination compensation operator of the single gun according to the first arrival travel time of observation and the theoretical travel time field of the single gun; The judging module is used for obtaining a VTI multi-parameter tomography result according to the objective function, the multi-parameter gradient and the preconditioning illumination compensation operator of all the cannons, judging whether the VTI multi-parameter tomography result meets the requirement, and outputting the VTI multi-parameter tomography result if the VTI multi-parameter tomography result meets the requirement; The illumination compensation module is used for obtaining an updated speed and anisotropic parameter model according to the accompanying field of the single gun and the preconditioning illumination compensation operators of all guns; Calculating a theoretical travel time field of the single cannon according to the speed and the anisotropic parameter model, and determining a single cannon objective function and an accompanying field of the single cannon according to the first arrival travel time based on an observation system file, wherein the method comprises the following steps: calculating a theoretical travel time field of a single gun according to the speed and the anisotropic parameter model by adopting a rapid scanning algorithm; determining a single-shot target function according to the first arrival travel time and the theoretical travel time field of the single shot based on an observation system file; Determining an accompanying field of the single cannon according to the observed first arrival travel time and the theoretical travel time field of the single cannon; Based on the observation system file, determining a single shot target function according to the observation first arrival travel time and the theoretical travel time field of the single shot, comprising: calculating the travel time difference between the observed first arrival travel time and the theoretical travel time field of the single cannon; Based on the observation system file, obtaining a single-shot target function according to the travel time difference of the single-shot : Wherein, the Represent the first The positions of the detection points; Representing a calculation region Any position in the interior, use Function of Control area Calculating an objective function at the inner wave detection point; Is the first arrival travel time calculated theoretically.
7. A processing device comprising computer program instructions, wherein the computer program instructions, when executed by the processing device, are for implementing the steps corresponding to the VTI medium-associated state method run-time multiparameter tomography method of any one of claims 1-5.
8. A computer readable storage medium, wherein computer program instructions are stored on the computer readable storage medium, wherein the computer program instructions, when executed by a processor, are configured to implement the steps corresponding to the VTI medium-associated state method time multiparameter tomography method of any one of claims 1-5.

Description

VTI medium accompanying state method travel time multi-parameter tomography method and system Technical Field The invention relates to the field of near-surface anisotropic parameter modeling, in particular to a method and a system for time-of-flight multi-parameter tomography of a VTI (transverse isotropy with a vertical symmetry axis) medium by a state method. Background The anisotropic characteristic of the underground rock stratum is common, and the anisotropy of the medium has serious influence on the kinematics and dynamics characteristics of seismic wave propagation, so that the construction of an anisotropic parameter model is important for seismic data processing and seismic imaging. In recent years, with the development of seismic exploration and observation methods such as "two wide and one high" and ocean bottom nodes (OBS), marine seismometers (OBS), among seismic data with large offset, the influence of anisotropy on the seismic data is particularly remarkable. The first-arrival wave carries rich underground speed and anisotropy parameter information in the propagation process of a near-surface medium, so that the establishment of an underground speed parameter and a VTI anisotropy model by using the first-arrival wave information is a common method in seismic exploration, wherein travel time information in the first-arrival wave information is the most robust and depends on an initial model to be low, so that a travel time chromatography method is often used for establishing an underground long-wavelength speed and VTI anisotropy parameter model. Based on different forward engines, three main travel time chromatography methods are generated, including a ray chromatography method based on ray tracing, a wave equation travel time chromatography method based on wave equation simulation or a finite frequency travel time chromatography method, and a travel time accompanying state method travel time chromatography method based on a travel function equation calculation travel time, wherein the three travel time chromatography methods all face the problem that one single speed parameter inversion is different from that of a first arrival travel time in an isotropic medium when the VTI medium is subjected to multi-parameter inversion, namely the sensitivity of travel time information to different parameters is changed along with angle, namely the travel time information is different from multi-parameter angle illumination, and the problem directly influences iterative updating of the VTI medium multi-parameter travel time inversion. In the VTI medium travel time multi-parameter inversion of ray tomography and wave equations, a learner has conducted preliminary studies on the angle illumination problem. In the ray tracing-based VTI medium travel time multi-parameter inversion method, researchers start from a Christoffel matrix and firstly deduce first derivatives of stiffness coefficients on phase velocity and group velocity, so that the characteristic that sensitivity of first-arrival travel time information on a plurality of parameters in the VTI medium changes along with angles is disclosed theoretically, and theoretical analysis solutions of sensitivity of qP, qSH, qSV three types of first-arrival travel time information in the VTI medium on the plurality of parameters along with the angles are provided. Based on the qP wave group velocity or the approximate expression thereof, the progressive approximate solution of the qP wave travel time information to the change of the VTI medium multi-parameter sensitive core along with the angle can be obtained. Based on the quasi-acoustic qP wave equation in the VTI medium, the expression of the qP wave finite frequency or wave equation travel time inversion multi-parameter sensitive core in the VTI medium can be obtained, and then the illumination conditions of the sensitivity of the plurality of parameters on different transmission angles can be calculated and analyzed numerically by designing observation modes of different transmission angles. Although the above method has revealed the problem of uneven angle illumination, the adverse effect of the problem on inversion and how to perform angle illumination compensation to improve the accuracy of inversion have not been studied intensively. Unlike ray-tomography and wave equation travel-time tomography methods, AST methods (travel-time multiparameter tomography methods based on the accompanying state method) do not require ray-tracing and computation of the friechet derivative matrix, have low memory requirements, are particularly suitable for parallel computation, and have been applied to joint velocity modeling of transmission and reflection, regional velocity modeling and VTI medium multiparameter modeling. However, the conventional AST methods all define the objective function based on the area, and the obtained accompanying equation depends on the surface normal, so that the detector can be defined on