Balancing Recovery of Upside Reserves Against Subsurface Uncertainties, West Patricia Field, Offshore Malaysia

摘要

Oil was discovered at West Patricia Field in December 2000,rnthirty-seven years after the first exploration well was drilled. Arnfast track three-well appraisal and six-well developmentrnprogram followed the discovery, which led to oil production inrnMay 2003.rnThe initial interpretation of logs, core and image datarnfrom the first four exploration and appraisal wells suggestedrnthat the West Patricia oil reservoirs were deposited as stackedrnchannel sands in a lower coastal plain setting. Howeverrnadditional data from wells drilled during the initial phase ofrndevelopment, suggested that these reservoirs were morernwidespread and that they were stacked river mouth bar sandsrndeposited in an estuarine lagoonal setting. This change inrndepositional concept has resulted in a reserves increase ofrn50%, which led to an increase in development scope in orderrnto ensure optimal reserves recovery. A field development planrnwas recently concluded to further develop the field in 2004.rnDespite this upside, several uncertainties remain.rnPressure data and fluid distribution indicate that the field couldrnbe more compartmentalized than can be interpreted fromrnseismic and that multiple gas-oil-contacts and oil-watercontactsrnmay be present.rnThis paper describes the integration ofrnsedimentological, stratigraphic and fluid pressure data tornoptimize reserves recovery from the West Patricia field whilstrnmanaging the remaining uncertainties.