LEONARD, A., M. BOWMAN, and E. JOLLEY, BP Exploration Company Ltd.,Aberdeen, Scotland

Abstract: Reservoir Management in Selected Basin Floor Submarine Fan Reservoirs from the UKCS

This paper reviews approaches to the exploitation of reserves from moderate to high net:gross submarine fan systems from the UK sector of the North Sea. Examples are given from the Forties, Magnus and Andrew fields. It is shown how contrasting reservoir management approaches and experiences can be related to architectural elements of the different fan systems. The submarine fans range in age from Jurassic to Palaeocene and the development schemes from platform drilled "conventional" wells to geosteered horizontal. These examples are broadly representative of other submarine fan reservoirs in the North Sea. Slope apron systems (eg. Brae Fields) are excluded from this discussion.

The Forties and Andrew fields have reservoirs of Palaeocene age (Forties and Andrew Formations respectively). The main reservoir in the Magnus Field is of Upper Jurassic age (Magnus Sandstone Member). All the reservoirs are, in summary terms, characterized by an upwards increase in depositional complexity and decreasing net:gross. This is caused by a change from amalgamated channelized sheet to channel and interchannel facies associations.

The Forties Field was initially developed using conventional near vertical production wells.Water flood was provided by water injection and a large regional aquifer. The production philosophy relied upon a stable rise of the OWC with progressive bottom up shut-off of water producing zones. This philosophy was successful during production from the lower amalgamated sheet facies. However, late in field life production relied upon accessing reserves in lower net:gross channel margin and interchannel facies - the higher net:gross channel facies having already been swept.The remain challenge for Forties is the identification of unswept targets, largely in interchannel locations using 3D seismic and surveillance data.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England