The Research On Finite-difference Contrast Source Inversion Of Viscous Acoustic Waves

FWI method can provide a good initial velocity model for migration imaging,and can also use the elastic parameters obtained from the inversion to perform reservoir inversion and fluid discrimination,with higher resolution and accuracy.Due to the absorption and attenuation of the stratum,the amplitude of the seismic wave is attenuated and the phase is distorted.In order to better suit the actual situation,the full waveform inversion is performed using the viscous acoustic equation by introducing complex velocity.However,the full waveform inversion method is mainly limited by computational cost and efficiency issues,so some scholars have proposed finite difference contrast source inversion methods.The finite-difference contrast source inversion method is a full-wave inversion method in the frequency domain.The forward operator of this method depends only on the background model and the inversion frequency.During the single-frequency inversion iteration process,the background model does not change.The forward operator is constructed and decomposed once,which greatly improves the calculation efficiency.In the forward modeling process,this paper selects different Q values to analyze the attenuation characteristics of seismic wave propagation in the stratum,and provides more realistic seismic data for subsequent inversion.In the inversion process,the L2 full variational constraint is used to make the inversion process more stable,and the L-BFGS optimization algorithm is used to update the inversion parameters,which reduces the number of iterations and improves efficiency,and has a better inversion effect for deep velocities.In addition,the paper also studies the sensitivity of the inversion velocity to the Q value within the same Q value error range during the inversion process,and provides a certain reference for the actual inversion work.The end of this article,the plane wave inversion method is finally applied to the viscous acoustic wave finite difference contrast source method,which further reduces the calculation amount during the inversion process and improves the inversion efficiency.