Abstract

A 4D feasibility study for the Balol Field in India shows that repeated seismic data can be used to observe changes in gas saturation. Two 4D analysis methods have been considered, first the conventional method by observing amplitude changes at selected interfaces, such as the top reservoir interface, and secondly to observe shifts in critical offsets for PP and PS reflections. Both methods show good potential for technical success. Typical near offset relative amplitude changes for PP-data are predicted to be up to 80-100%, and the PP critical offset change is expected to be 70m. Similar results are expected for the PS data.