Imaging Beneath Shallow Gas Using Wave Equation Tomography – A Field Data Example from Greater Cassia, Trinidad

C007 Imaging Beneath Shallow Gas Using Wave Equation Tomography – A Field Data Example from Greater Cassia Trinidad M.M.N. Kabir* (BP America Inc.) U. Albertin (BP America Inc.) M. Zhou (BP America Inc.) V. Nagassar (BP Trinidad) E. Kjos (BP Trinidad) & P. Whitaker (BP Trinidad) SUMMARY Shallow localized gas pockets cause challenging problems in seismic imaging because of the sags and disturbances they produce on imaged reflectors deep in the section. In addition the presence of shallow gas produces strong surface related and interbed multiples making velocity updating very difficult. Usual reflection tomography techniques may need many iterations to