First Gas after 40 Years - The Geophysical Challenges of the Saturn Gas Complex

ConocoPhillips has held Block 48/10b in the UK southern North Sea for some 40 years. The first gas production from the Saturn field in this block was achieved in September 2005. The main geophysical challenge of this block is to understand the sub-salt wall structure of the Rotliegendes reservoir. A variety of geophysical techniques have been applied, some of the earlier methods are briefly reviewed. The main emphasis of this presentation is the interpretation of the pre-stack depth migrated data and its subsequent depth conversion, including a subjective method of removing the artefact created under the salt wall overhangs. The results of the recent horizontal wells, together with the pre and post drilling interpretations are used to show the limitations of the seismic reflection data to predict the details of the reservoir structure beneath this salt wall. Finally, a brief review will be made of the two previously stranded gas fields that will be developed using these new Saturn facilities.