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ABSTRACT: Tectonostratigraphic controls on turbidite depositional processes in Brunei

Allman-Ward, Patrick, Jan Pieter Tromp, and Abdullah Ibrahim , Brunei Shell Petroleum, Seria, Brunei

Brunei Shell Petroleum and its competitors have drilled 22 wells in Brunei waters to date which have penetrated turbidite reservoirs. These have been both in deepwater sensu stricto and in shallower waters on the shelf targeting the underlying, deeper turbidite objectives. Exploration success rate has been high, over 70% of the tests having discovered hydrocarbons but commercial success rates have been relatively low (14%). All of the wells drilled to date have been in the slope or by-pass environment. The results have highlighted that the key element in commercializing turbidite discoveries in Brunei in this setting is adequate reservoir development. One of the most important challenges is therefore to identify where the turbidite sands are best developed prior to exploration drilling.

The late Tertiary depositional system offshore Brunei is strongly progradational. The sedimentation history has been dominated by the Baram Delta to the southwest and the "Champion Delta" to the northeast. The shelf profile is characterized by a steep slope (up to 10 degrees in places) with a relatively rapid descent into extreme water depths (>2500m) in the centre of the NW Borneo Trough. The potential for turbidite reservoir development in Brunei has been related to three controlling mechanisms: source material, delivery system and accommodation space. The impact of these mechanisms on the occurrence of reservoir quality turbidite sands in the by-pass setting is discussed and their evolution through time.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia