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The Balder oil field in blocks 25/10 and 11 in the Norwegian sector of the North Sea contains 25° API oil in a Paleocene deep-water sandstone reservoir. The sands were deposited from high concentration, high-energy turbidity currents as a complex of channelized sand lobes which formed a small fan. Depositional topography and subsequent submarine erosion created a geometric closure on the upper surface of the fan. Oil is stratigraphically trapped by this closure. Recognition and definition of this mounded surface on seismic records and the development of a sedimentary model has made it possible to drill successful appraisal wells after disappointing initial drilling results.

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