Abstract

The Brent Field consists of a major, westerly dipping fault block, with a crestal area broken up into a series of slumped fault blocks. The primary phase of development has concentrated on water flooding the West Flank, but effort is now being applied to recover the oil in the slumped blocks. This paper describes the various studies undertaken to formulate a development plan for the estimated 13 x 10 ⁶ m ³ (80 MMSTB) of oil reserves in the slumps of the Brent Reservoir and presents initial well results. A valid geological interpretation was crucial to successful development planning for the slumps. Structural interpretation is difficult due to limited seismic resolution, but the geological model has been supported by a review of structural analogues and by the limited well performance data. The slump faults are interpreted as running predominantly north-south. As such, they provide a significant barrier to west-east flow, while allowing better communication in the north-south direction. Development options have been evaluated by reservoir simulation based on this geological interpretation. East-west communication will be too poor to enable the slumps to be developed at reasonable rates by relying solely on pressure support from West Flank water injection. In addition, the use of horizontal wells, as compared with conventional deviated wells, has been shown to give significant benefits by providing offtake points in several slump blocks with one well, thereby improving the sweep efficiency and increasing the recovery whilst optimizing rig usage. A development plan has been formulated on this basis with a series of roughly parallel east-west horizontal oil producers, interspersed with horizontal water injectors. This plan is now being implemented and the first wells are now on production.