Least-squares reverse time migration of marine data with frequency-selection encoding
KAUST DepartmentEarth Science and Engineering Program
Earth Sciences and Engineering Program
Physical Sciences and Engineering (PSE) Division
Environmental Science and Engineering Program
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AbstractThe phase-encoding technique can sometimes increase the efficiency of the least-squares reverse time migration (LSRTM) by more than one order of magnitude. However, traditional random encoding functions require all the encoded shots to share the same receiver locations, thus limiting the usage to seismic surveys with a fixed spread geometry. We implement a frequency-selection encoding strategy that accommodates data with a marine streamer geometry. The encoding functions are delta functions in the frequency domain, so that all the encoded shots have unique nonoverlapping frequency content, and the receivers can distinguish the wavefield from each shot with a unique frequency band. Because the encoding functions are orthogonal to each other, there will be no crosstalk between different shots during modeling and migration. With the frequency-selection encoding method, the computational efficiency of LSRTM is increased so that its cost is comparable to conventional RTM for the Marmousi2 model and a marine data set recorded in the Gulf of Mexico. With more iterations, the LSRTM image quality is further improved by suppressing migration artifacts, balancing reflector amplitudes, and enhancing the spatial resolution. We conclude that LSRTM with frequency-selection is an efficient migration method that can sometimes produce more focused images than conventional RTM. © 2013 Society of Exploration Geophysicists.
SponsorsWe thank the sponsors of CSIM consortium (http://csim.kaust.edu.sa) for their financial support. We are also grateful to the supercomputing lab at King Abdullah University of Science and Technology (KAUST) for their computer facilities and technical support. The comments from the Associate Editor Stephane Operto, reviewer Yong Ma, and two other anonymous reviewers have greatly improved the quality of the paper.
PublisherSociety of Exploration Geophysicists