【作者】 李桂花；

【导师】 朱光明；

【作者基本信息】 西安科技大学 ， 地质工程， 2008， 博士

【摘要】 井间地震是油气田勘探开发的一项关键技术,能够实现两井之间构造和储层等地质目标的高精度成像。井间地震数值模拟是研究复杂地层中井间地震波传播规律的有效手段,可以帮助认识井间地震的复杂波场。而识别和分析井间地震波场中各种主要波的传播特征是井间地震采集设计、资料处理、解释以及井间地震资料利用的前提。论文首先研究井间地震波场数值模拟的方法,接着根据模拟生成的波场识别和分析井间各种主要波的传播特征。重点研究了三种地震波场数值模拟方法:一是弹性介质中改进的突变点加插值的射线追踪方法,这种方法的特点是能够快速地追踪井间地震记录的直达P波和S波、上行和下行反射波、PS和SP反射和透射转换波及干扰波(井筒波),并模拟生成多炮多道的水平分量和垂直分量的井间地震记录。本文根据模拟的结果,结合理论分析,系统总结了上述主要类型波在共炮点、共接收点、共偏移距和共中心深度点等4种道集中的传播规律。模拟的记录和野外实际采集的井间地震记录进行对比,可以识别出野外复杂波场中主要类型的波,以及他们的传播规律,分析结果证明数值模拟是正确的。二是VTI介质交错网格高阶有限差分数值模拟方法,选择这种方法是因为井间地震观测的波场常常显示出明显的各向异性,另外,井间地震要求有较高的模拟精度。本文在前人工作的基础上,推导了VTI介质时间-空间域二维三分量一阶速度-应力弹性波方程及其任意偶数阶时间和空间精度交错网格差分格式,特别是推导了Y-分量的方程、差分格式和边界条件,并研发了相应的数值模拟软件,能够模拟声波、各向同性及横向各向同性介质中各种复杂构造的二维三分量波场,能清楚地识别出快纵波、慢纵波、快横波和慢横波。模拟的结果解释了实际野外地震记录上由于各向异性引起的一些难解释的现象。三是粘弹各向异性介质频率空间域有限差分数值模拟方法,选择频率域主要是易于模拟衰减。本文在重复前人关于频率空间域各向异性准P波波场推导的基础上,补充推导了加入粘弹性的公式,研发了弹性和粘弹性VTI介质准P波正演模拟软件,能模拟更接近井间实际介质的各向同性、各向异性准P波的波场。在频率空间域有限差分算法的实现中改进了大型稀疏带状矩阵的解法,解决了存储空间不够和计算时间过长的问题,解决了利用傅里叶变换的周期性和共轭对称性计算频率域波场的问题。更多还原

【Abstract】 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. .更多还原