Least-squares reverse-time migration with a wavefield-separation imaging condition and updated source wavefields

Abstract

Directly imaging steeply dipping fault zones is difficult for conventional migration, including reverse-time migration (RTM). We developed a new least-squares RTM (LSRTM) method to directly image steeply dipping fault zones. The method uses a wavefield-separation imaging condition and updated source wavefields during each iteration. Our new imaging method produces horizontal-looking images that show mostly steeply dipping fault zones. Conventional least-squares RTM does not update source wavefields and cannot directly image vertical fault zones. We numerically determined that it is crucial to update source wavefields to image steeply dipping fault zones. Using synthetic seismic data, we proved that our new LSRTM method can directly image steeply dipping fault zones with dipping angles up to 90°. Compared with conventional LSRTM, our LSRTM method was less sensitive to the smoothness and the velocity error of the initial migration velocity model.

Progress in monitoring strategies for risk reduction in geologic CO2 storage

“…These investigations focused on improving subsurface spatial resolution via the use of 3D-VSP technology compared to 3D surface seismic technology. The second investigation was related to improving seismic imaging through least-squares, reverse-time migration processing (Tan and Huang, 2014). This processing allows coping with the sparse distribution of VSP seismic sources often found in land VSP designs, and the avoidance of processing artifacts that may mimic low offset faults or other subsurface discontinuities.…”

Least-squares reverse time migration with and without source wavelet estimation

“…Therefore, LSRTM can produce migration images with better quality than conventional migrations (Ji, 2009;Dai et al, 2012Luo and Hale, 2014;Dutta and Schuster, 2014;Zhang and Schuster, 2014;Tan and Huang, 2014a;Aldawood et al, 2015;Wong et al, 2015;Y. Zhang et al, 2015) by removing migration artefacts, improving the illumination and revealing more subsurface details.…”

Joint least-squares reverse time migration of primary and prismatic waves

“…Nevertheless, owing to the high-frequency approximation for the ray-based Kirchhoff migration method, it cannot handle complicated subsurface structures, such as salt flanks, which are important geologic features for oil and gas exploration and production. Tan and Huang (2014) propose a least-squares reverse time migration (LSRTM) method that directly images steeply dipping fault zones with a wavefield-separation imaging condition. It also updates the migration velocity model, and hence the source wavefields, at each iteration.…”