【摘要】 目前的地震勘探技术是建立在均匀、各向同性、完全线性弹性介质假设理论基础上的,对于精细地质构造的识别难以突破理论地震分辨率的限制。若地震建模时考虑到地下介质的初始应力场不为0这一客观存在,就必须按照介质的非均匀或各向异性进行参数表征。在此基础上,进行了均匀各向同性、非均匀和各向异性介质假设下射线追踪的数值模拟;对比分析发现,即使对于垂直断距小于3m的正断层(且假设无水平断距),在现有地震采集频带下,断层也会在非均匀与各向异性介质假设下的地震反射信号振幅和相位上表现出较大的异常;其异常变化的空间范围远大于断层垂直断距,使得识别这种小断层成为可能或可靠性提高;而且数值模拟显示小断层的各向异性波场特征格外明显。实际多分量地震数据解释也显示,通过PP、PS波的对比,有利于识别小断层。更多还原

【Abstract】 The study of Kineto-Elastodynamic faced serious heterogeneous and anisotropic problems,when the assumption that the initial stress field of subsurface formations approximates to zero can not be matched.In inhomogeneous or anisotropic media,a minor fault,with vertical throw less than 3 m and no horizontal separation,can be modeled and simulated in different elastic parameters.Even with a limited frequency bandwidth of reflections,just like the field seismic sampling,the minor fault shows great anomalies in the amplitudes and phases after numerical simulation with ray-tracing method.The amplified phenomena of reflecting anomaly,greater than vertical fault throw,made it possible to identify a minor fault.Especially,the characteristics of elastic wave propagation show stronger anomalies under the assumption of anisotropic media.Simulation and two field examples demonstrate that minor faults beyond seismic resolution limit can be identified through comparing PP- and converted PS- wave with a relatively higher precision.更多还原