Improving Imaging and Inversion Through Least-Squares Q-Kirchhoff APSDM: A Case Study from Offshore China

Abstract

Least-squares migration (LSM) has become an increasingly important imaging tool in the seismic industry. It can successfully address imaging issues related to insufficient illumination and mitigate both migration artifacts and noise. More recently, a number of case studies from around the world have shown that LSM provides greatly improved seismic imaging. However, only a few examples reveal its advantages in both imaging and amplitude-versus-offset (AVO) inversion. For the amplitude aspect, compensating the effect of anelastic absorption and elastic scattering during propagation inside the earth has become increasingly popular over the past few years. The anelastic absorption and elastic scattering causes frequency-dependent amplitude decay, phase distortion, and resolution reduction. This is often quantified by the quality factor commonly called Q model. This effect can be largely compensated through Q prestack depth migration (QPSDM). Therefore, QPSDM has become an effective solution for seismic imaging in areas where strong absorption anomalies exist in the overburden. However, the excessive noise often resulting from QPSDM poses a big challenge to its application. In this paper, we propose a least-squares Q migration (LSQM) method that combines the benefits of both LSM and QPSDM to improve the amplitude fidelity and image resolution of seismic data. We also demonstrate that both seismic imaging and AVO inversions at wells can be significantly enhanced through image-domain single-iteration least-squares QPSDM Kirchhoff migration.