Late Jurassic Structural Inversion in the North Viking Graben and East Shetland Basin, UK North Sea

Abstract

Interpretation of regional seismic data and analysis of available well data from the North Viking Graben suggest that a significant phase of structural inversion took place in the Late Jurassic and also in the early Cretaceous. It is believed that this inversion may be a consequence either of compression of the basin as a whole or alternatively, transpressional uplift along offset NW-SE fault systems. The north-south trending Penguin Ridge in UKCS quadrant 211 is interpreted as being such an inversion feature. The Penguin Ridge may well be an extreme example of apparent compression within the context of the Northern North Sea. However, it is clear that less well-developed structures of a similar type have previously been interpreted as simple extensional fault blocks. A compressional or transpressional mode of formation has implications for both reservoir diagenesis and faulting and thus important consequences for exploration play evaluation. It is also proposed that the Penguin Ridge is the northerly limit of a north-south trend or fairway in which compressional features can be observed from regional and field specific seismic data. Certainly there are many anomalous structures within the complex crestal areas of the majority of the Brent Province fields. The impact of such a model is the subject of continuing studies, but it is clear that as the search for more subtle plays intensifies in mature exploration areas such as the North Sea, it is important that the explorationist keeps an open mind, especially when confronted with apparently anomalous data.