Petroleum geology of the Gorm Field, Danish North Sea

Abstract

The Gorm field is located within the Central Graben of the North Sea. It is a broad, domal, saltinduced structure of 750 ft closure, cut by a major, NNE-SSW striking, normal fault. The downthrown, 'western A block is dissected by high angle, tensional faults while the upthrown, eastern B block is relatively unfaulted. Downthrow of the A block appears to have been accompanied by a southward tilt relative to the B block. The reservoir rock comprises high porosity, low permeability, Danian and Maastrichtian chalks which are in pressure and fluid equilibrium. The upper Maastrichtian, with porosities of 30-40% , contains the bulk of the reservoir volume, porous Danian also contributing significant volume in the B Block. Gorm is an undersaturated oil reservoir with no initial gas cap and an oil column of up to 500 ft. Fluid levels are horizontal in the B block and apparently dipping to the south in the A block. To date, production performance in A block wells is better than that in B block wells.