Summary

Tectonic structure is commonly a key factor in the assessment of trap development and trap integrity prior to drilling in structurally complex basins such as the U.K. North Sea. Well and core data show that sealed faults are generated by a number of processes in the basin, whereas fault breaching and leaking is evidenced by the known occurrence of dry or underfilled structures at Mesozoic levels (often with residual hydrocarbons indicating previous charging episodes) and by the widespread occurrence of Jurassic sourced oils in Tertiary reservoirs. Although these processes have for some time been invoked to explain certain geological observations in the North Sea, the advent of 3D seismic datasets (including coherency cube data), together with seismic attribute mapping and the widespread utilisation of image processing techniques (e.g. false coloured shaded relief mapping) now mean that both the location and geometry of fault zones can be far more readily defined. Such high quality seismic data, along with an increased understanding of fault zones and faulting processes, is demonstrated to have exerted a major impact on our understanding of the distribution, size and internal compartmentalisation of hydrocarbon accumulations. Using a number of selected examples, we show how such processes have controlled the distribution of hydrocarbons and how they impact on field development strategies. Finally, the wider implications of these processes in hydrocarbon exploration and production are considered.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah