Correlation of Fluvial Reservoir Sequences: A Case Study Using the Brent Field Statfjord Formation, Northern North Sea

D. J. Prosser, Li Bingjian, M. J. Hole, B. P. J. Williams, A. C. Morton

The Statfjord Formation within the Brent Field mainly consists of a highly heterolithic succession of alluvial sandstones, siltstones, and mudstones (the Erikson and Raude Members). The uppermost Statfjord Formation, however, comprises a thin unit of medium - coarse grained shallow marine sandstones (the Nansen Member). Analyses of material from 11 cored wells, and wireline log suites from a further 61 non-cored wells has revealed a distinct pattern of "sequence" development which is present throughout the Statfjord Formation, of the Brent Field. A very poorly preserved biota has precluded biostratigraphic correlation of the main Statfjord Formation fluvial suite. Furthermore, the positions of lithostratigraphic markers (e.g. the base of the Nansen Member) within a sedime tary succession frequently reflect variation in the spatial development of facies, rather than chronostratigraphically equivalent events. Thus, if derived from purely lithostratigraphically driven correlations, the reservoir geologists' perception of parameters essential for flow unit designation prior to field simulation studies (e.g. sand-body connectivity), are often poorly constrained. The study has applied a multidisciplinary approach to the problem of correlation using palaeosols as potential indicators of "channel proximity" within a flood-basin. This, together with field production data, whole-rock geochemical and heavy mineral analyses, have allowed a novel approach to be used in the interpretation of reservoir sandstone interconnectedness.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995