Imaging Through Mega Gas Clouds with FWI and Q TTI RTM

We present a complete technical package to tackle the complex wave propagation and anelastic energy losses associated with mega gas clouds. We started by running FWI to resolve the velocity of the shallow gas clouds, followed by reflection tomography. We then conducted FWI-guided Q tomography to obtain high-resolution absorption model. For the deep gas clouds, since their depth and the incurred low signal-to-noise ratio in the CMP gathers are beyond the limit of these geophysical methods, we moved on with geologically-guided scenario testing in intense collaboration with geologists. Finally, we carried out visco-acoustic TTI reverse time migration (Q TTI RTM) to better deal with the issues of multi-pathing and strong attenuation. This complete package brings significant uplift to the image as compared to the vintage QPSDM result, and therefore can serve as an effective option before turning to C-wave imaging.