Study On The Method Of Viscoacoustic Least Square Reverse Time Migration

The viscosity is widely existed in the earth,which can lead to the amplitude attenuation and phase variation during the process of seismic propagation.Thus it will decrease the imaging resolution and affect the imaging energy based on the assumption of traditional acoustic wave,resulting in the bad image.Therefore the influence of the viscosity should be considered when imaging.Least square migration(LSM)is a linearized inversion method,which can improve the migration resolution and suppress migration artifacts with true amplitude images.For the problem of viscous imaging and the advantage of least square reverse time migration(LSRTM),a viscoacoustic LSRTM method is proposed.The viscoacoustic least square migration operator,demigration operator and gradient formula are derived based on the viscoacoustic wave equation for the General Standard Linear Solid.A viscoacoustic adjoint operator and low-pass filtering in frequency domain are introduce to overcome the instability during the seismic wave back-propagation in the viscoacoustic media.The polar encoding technology is used to decrease the computational cost and memory storage of the viscoacoustic LSRTM,which can make it possible to be practical.Finally,the method is developed to propose a 3D a viscoacoustic LSRTM method.The test of the flat model,Marmousi model and salt dome model with Q prove the accurate of the viscoacoustic LSRTM and the advantage over the viscoacoustic RTM and acoustic LSRTM.At last,real data are test to get the high quality image,which suggests that the proposed method is suitable for real data.