弹性介质中谱元法叠后逆时偏移方法研究

Spectral-element method for post-stack reverse-time migration in elastic media

(中国石油天然气集团公司冀东油田勘探开发研究院,河北唐山063004)

Exploration and Development Research Institute,Jidong Oilfield,CNPC,Tangshan 063004,China

偏移成像是地震资料处理的关键技术之一,而偏移的精度和效率是偏移方法研究的重点和难点。开展了基于高精度和适应性强的谱元法叠后逆时偏移研究。应用波动方程数值模拟得到等价叠加地震资料,利用界面点法最小走时射线追踪技术得到地下介质各点的走时,以此作为成像条件,基于爆炸源成像原理实现叠后逆时偏移。设计了层状和界面起伏两个地质模型,分别在各向异性介质和各向同性介质条件下对正演模拟结果进行了谱元法叠后逆时偏移。结果表明,各向同性和各向异性介质条件下的偏移结果都与初始模型相吻合。

Migration is one of the key technologies for seismic data processing.However,the precision and efficiency of migration is the difficulty and focus for the study on migration methods.Aiming at this problem,we started post-stack reverse time migration research from the basis of spectral element method with high precision and strong flexibility.Equivalent stack seismic data was obtained based on numerical modeling of wave equation.Meanwhile,minimal traveltime ray tracing technique was used to achieve the traveltime of every point in the subsurface medium,which took the interface as second source.Taking the above results as imaging conditions,post-stack reserve time migration was realized based on the explosive-source imaging theory.Then,two geologic models were designed,including layered model and interface undulated model,which were used to carry out post-stack reverse time migration by spectral element method on forward modeling results in anisotropic and isotropic medium.The results indicate that the migration results are coinciding with initial model in anisotropic and isotropic medium.