An integrated 3D seismic, petrophysical and analogue core study of the Mid-Eocene Grid channel complex in the greater Nelson Field area, UK Central North Sea

Abstract

This paper presents an integrated seismic, petrophysical and analogue core study of the Mid-Eocene Grid deep-water Sandstone Member from the Nelson Field area, Central North Sea. Two possible turbiditic units were identified in seismic data. Grid 1 shows channel-like features and a complex stratigraphy whilst Grid 2 consists of scattered bright amplitude events (shown to be slumped shales and chalky limestones by cuttings analysis). Lower Eocene Tay Sandstone Member core from the nearby Gannet Field provided an analogue for sedimentary facies. This enabled petrophysical and seismic observations of the Grid Sandstone Member to be tied to sedimentological facies. An integrated model shows five facies associations and a complex reservoir quality distribution. A comparison with outcrop and seismic examples of channelized turbidites indicates that the Grid system represents a medium-scale channel complex, exhibiting multi-storey, nested offset stacking. This work presents a new example that provides a link between laboratory experiments on topographic interaction of turbidite flows with seismic-scale observations and facies determination. The Grid system also adds to our knowledge of Palaeogene turbidite evolution from sheet-like to channellike forms and provides a useful analogue for improving hydrocarbon exploration and production efficiency in adjacent areas.