Saga2013_day3_session_10b_davids

The Orange Basin underlies the Atlantic Ocean off the South African west coast and covers an area of approximately 160 000 km2 to the 2 000 m isobath and the drift sequence can be as thick as 7 km in the north, thinning to 1-3 km in the south. The Orange Basin is largely underexplored with only one well per 4000 km2 and has potential for the successful accumulation of hydrocarbons, possibly in significant quantities. The seismic reflection data obtained in the Orange Basin portray the subsurface in recorded two-way time. All the interpretation for this basin has been done in the time domain, which is quick and adequate for many situations. Stratigraphic interpretation in the time domain can be fine for seismic facies and sequence stratigraphic analyses, where the interpretation remains largely the same with changing structure. However, structural interpretation in the time domain is risky as it means accepting the risk of assuming a constant velocity model, or that all possible velocity deviations can be accounted for by the interpreter. The aim of this paper is to discuss the benefit of acquiring prestack depth migration seismics in future, compared to prestack time migration gathered in the Orange Basin to date. Further 2D and 3D seismic acquisition, which is depth migrated, as well as drilling programs will be of great benefit in mitigating the geological risk. Improved integrity of seismic data through depth imaging, will potentially reduce the exploration cycle time, allow for improved well planning and increase accuracy especially when fault delineation is critical.