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Study On Crosswell Seismic Numerical Simulation And Wave Field Characteristics

Posted on:2009-10-25Degree:DoctorType:Dissertation
Country:ChinaCandidate:G H LiFull Text:PDF
GTID:1100360245472933Subject:Geological Engineering
Abstract/Summary:PDF Full Text Request
Cross-well seismic is an important technology in exploration and development of oilfield. This technology could help us in high precision imaging of geological targets as structure and reservoir between wells. The numerical simulation of crosswell seismic is an effective method in studying seismic wave propagation regularity of complex strata between wells which could help us in recognizing complex wave fields of crosswell seismic. The recognition and analysis of crosswell seismic wave propagation is a precondition of crosswell seismic acquisition, data processing and explanation.In this paper, the numerical simulation methods within crosswell seismic wave fields have been studied, and the main waves'propagation characteristics of crosswell seismic wave field has then been recognized and analyzed based on the analysis of the wave fields generated by numerical stimulation. There are three numerical stimulation methods for seismic wave fields: the first method is ray tracing of mutational point with interpolation in elastic medium, the point of this method is that it could simulate the seismic records which include horizontal component and vertical component of multiple shots and channels crosswell seismic records in a short time. With this method, one can get crosswell seismic records include P-wave and S-wave first-break,up-going reflection wave and down-going reflection wave,reflection and transmitting PS or SP converted wave and tube wave. According to the modeling results and combined with the theoretical analysis, this paper summarizes propagation regularity of the main type waves systematically, which are in the four different gathers of CSP, CRP, COP and CMP. With comparison between modeling recordings and field crosswell recordings, the main types of wave can be recognized in the complex wavefield, and the numerical simulation is proved right under the analysis of propagation characteristics. The second method is the numerical simulation methods of staggered grid high-order finite difference in the VTI media, because the wave fields observed from well-to-well can show obvious anisotropy, and what's more, the cross-well seismic demands higher simulation precision. This paper is based on summary and analysis of predecessor's experience to deduce wave equation of three-component, first-order stress-velocity elastic wave equation in VTI medium in time-space domain, and any even-order accurate staggered-grid finite-difference scheme in time-space domain. Specially the Y-component equation,absorbing boundary condition, difference scheme have also been deduced and the software of numerical simulation soft has been researched and developed by myself. The software could simulate sonic wave and three-component wave fields in isotropic and anisotropic medium. So one can recognize fast and slow P-wave,fast and slow S-wave, one can also explain some difficult phenomena of actual seismic records that caused by anisotropy with the simulation result. The third method is the numerical simulation method of anisotropic medium in frequency-space domain. The main reason to choose frequency domain is that it is easy to simulate attenuation in frequency domain. This paper is based on the propagation formula deduction of quasi-p wave in anisotropic media, the formula of attenuation wave propagation which is in viscoelastic media is deduced. And the forward modeling software of quasi-p wave in elastic and viscoelastic media is developed which can closely model real crosswell seismic quasi-p wave fields in isotropic and anisotropic media. At the same time, on the aspect of finite-difference method in frequency-space domain, it improves the algorithm of large sparse-band matrix and solves the problem of memory space inadequate and long computing time, finds the way to calculate wave fileds in frequency domain on the periodicity and conjugate symmetry of fouier transform. .
Keywords/Search Tags:Crosswell seismic, Numerical simulation, Wave filed character, Ray method, Staggered-grid high-order finite-difference, Frequency-space domain, Anisotropic, Viscoelastic
PDF Full Text Request
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