Controls on Late Jurassic, subtle sand distribution in the Tampen Spur area, Northern North Sea

Abstract

The role of fault growth and linkage is an important, but poorly understood, factor in controlling the distribution of sediments within extensional settings. Tectonostratigraphic analysis of the Statfjord East fault system, located in the East Shetland Basin of the Northern North Sea, demonstrates the importance of Late Jurassic normal faulting in controlling the nature of subtle, hanging wall traps. Wells in Norwegian Block 34/7 have penetrated prospective sandstone reservoirs that correlate with several thin, but seismically resolvable, units within syn-rift sediments of the Statfjord East hanging wall. Detailed 3D seismic interpretation and mapping of amplitude anomalies in Block 34/7 and the adjacent part of Block 33/9 reveal a number of spatially discontinuous stratigraphic units within the Late Jurassic, syn-rift Draupne Formation. These depositional units are spatially related to sub-basins, which are controlled by interaction and linkage of several en echelon fault segments. The main control on the distribution of local depocentres is the along-strike displacement variation associated with fault propagation by segment linkage. A close association between sandstone occurrence and structural position, suggests a model in which shoreline migration is controlled by the dynamics of fault lengthening through time.