【作者】 梁锴；

【导师】 吴国忱；

【作者基本信息】 中国石油大学 ， 地球探测与信息技术， 2007， 硕士

【摘要】 地震各向异性研究已经成为地震学研究领域中的前沿课题之一,开展地震各向异性研究对认知地球介质结构、勘探开发复杂油气藏和预报地质灾害均具有理论意义和实用价值。针对沉积岩普遍存在的各向异性介质,深入研究了TTI介质弹性波传播特征、弹性波波动方程分解和VTI介质Born近似qP波深度偏移成像方法。相速度、群速度是弹性波传播的重要特征。从TTI介质弹性波Christoffel方程出发,研究了TTI介质弹性波传播的相速度、群速度和偏振方向。在此基础上,进一步讨论了TTI介质弹性波反射、透射特征,为各向异性介质AVO研究奠定了理论基础。波动方程分解在地震偏移成像和多分量地震学理论研究中具有非常重要的作用。从Thomsen弱各向异性理论与声学假设条件两个途径对TTI介质弹性波波动方程进行了分解,获得了TTI介质中描述qP波传播具有较高精度的波动方程,为研究VTI介质单程双域传播算子和建立VTI介质深度偏移算法奠定了理论基础。在波动方程深度偏移成像过程中,波场延拓算子和算法流程是地震偏移成像的核心。从VTI介质qP波波动方程出发,建立了VTI介质Born近似qP波单程双域传播算子,由各向同性介质qP波扩展局部Born近似传播算子和各向异性扰动项组成。在该算子研究的基础上,建立了VTI介质qP波深度偏移算法流程,并实现了叠前和叠后深度偏移。叠前深度偏移和叠后深度偏移均获得了较好的成像效果,证明了VTI介质深度偏移成像算子的正确性、有效性和适应性。更多还原

【Abstract】 Seismic anisotropy has been one of the latest scientific research topics in seismology, and also it is a great challenge for seismology theory study and application. Carrying out seismic anisotropy research has great academic significance and applied value for the cognition of earth media configuration, the exploration and development of complex oil gas reservoir, the forecast of the geological disaster. For the ubiquitous anisotropic media in the sedimentary rock, the elastic wave propagation characteristics in the TI media, the decomposition of elastic wave equation, one-way dual-domain propagation operator for qP wave and the wave equation depth migration imaging method in VTI media are systematically studied.Phase velocity and group velocity are important characteristics of elastic wave propagation. According to the elastic wave Christoffel equation in TTI media, we have a research on phase velocity, group velocity and polarization direction for elastic wave propagation in TTI media. Based on them, elastic reflection characteristic and transmission characteristic in TTI media are discussed, which provides a basis for anisotropy AVO study.Wave equation decomposition plays a very important role in the research of seismic migration imaging and multi-component seismology. The decomposition of elastic wave equation in TTI media is carried out on the base of Thomsen weak anisotropy theory and acoustic assumption condition. The result shows that high accuracy wave equation describing qP wave propagation in the TTI media can be obtained through wave equation decomposition, which plays a foundation for studying one-way dual-domain propagation operator in VTI media and establishing depth migration algorithm in VTI media.In the process of wave equation depth migration imaging, the core things of seismic migration imaging are the wave field propagation operator and the algorithm flow. On the basis of qP Wave equation in VTI media, we thoroughly studies Born one-way dual-domain propagator for qP wave in VTI media. The operator consists of the extended local Born approximate operator in isotropic media and anisotropic perturbation operator. Basing on one-way dual-domain propagator in VTI media, the qP wave depth migration algorithm flow in anisotropic media is established, and prestack and poststack depth migration are carried out. Not only prestack depth migration but also poststack depth migration has obtained good imaging results, and these results validate the accuracy, validity and compatibility of depth migration imaging operator in VTI media.更多还原