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Abstract: Targeting Infield Wells on the Forties Field

Steve Chappell, Brian Gane, Jason Scott, John Williams

The Forties field has produced some 2200 mmbbls of oil. The remaining reserves are estimated at 280 mmbbls. Current production is 120,000 b/d of which some 45,000 b/d comes from 20 new infield wells drilled since May, 1992.

These wells have been sited, with considerable success, utilising the existing reservoir description. However, as the drilling programme progresses, future wells will be targeted on sites carrying significantly more uncertainty and risk and improvements in the reservoir description are required.

New reservoir models have been built for the Alpha platform sector of the Field and these have been used to evaluate upcoming infield well locations. The models incorporate new mapping of the 1988 3D seismic data which have been reprocessed both to understand better the internal reservoir geometries and to map and quantify reservoir rock properties using seismic attributes.

The Forties reservoir is a sand-rich Palaeocene submarine fan which comprises a hierarchy of interwoven channels. Higher order channel systems can be mapped using the reprocessed seismic data. However, the lower order channels, which are fundamental in Controlling fluid movement, are below seismic data resolution such that stochastic modelling has been used to describe this level of heterogeneity.

Reservoir simulation studies show that the new models more accurately describe the vertical distribution of oil and water in existing wells.

The work has been used to reduce pre-drill risk on net oil column and fluid production rates.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France