Plane-wave least-squares reverse time migration based on the first-order velocity-stress equation in anisotropic media

Key words:  anisotropic media  first-order velocity-stress equation  linearized modeling operator  plane-wave coding  plane-wave least-squares reverse time migration

Abstract:

High-precision imaging of anisotropic media has always been a research hotspot but remains a difficulty in the field of seismic exploration,in which the computational efficiency is one of the key factors restricting the application of inversion imaging method. In order to meet the demand of precise exploration for anisotropic reservoir,this paper first derives the imaging operator and linearized forward modeling operator suitable for inversion imaging based on the first-order velocity-stress pseudo-acoustic-wave equation of anisotropic media. The gradient of functional and scattered wavefields is then constructed. In the least square inversion framework,an anisotropic media pseudo-acoustic-wave least-squares reverse time migration method was developed afterwards.In order to improve the inversion efficiency,plane-wave coding technique,precondition,regularization,and GPU acceleration were introduced, and a stable and efficient plane-wave least-square inversion imaging optimization strategy for anisotropic media was developed. Tests on typical models show that this approach can perform with high imaging efficiency amplitude-preserving imaging on complex structures such as overthrust, high-steep-dip structure, rugged shallow surface layer and so on, and also can automatically suppress crosstalk and migration noise with the iteration to improve the overall imaging quality.