Foinaven Development - Breaking the Mould

Colin H. J. MacLean, J. Douglas Boyd, and Peter J. Smith

Foinaven Phase I, the first oil field development West of Shetland (UK), has produced a new standard in the time between discovery and first oil. This performance improvement stems from the clarity of hydrocarbon imaging available with new technology based on 3D seismic data.

Oil in the Foinaven field (discovered in late 1992) lies within Palaeocene reservoir sands. Reservoir quality is excellent, although the sands are relatively thin, distributed over a large area and are overlain by a gas cap.

Prior to appraisal drilling, 3D seismic data were acquired as part of an extensive 2000-sq-km survey shot in the summer of 1993. The conventional 3D seismic data were inverted to produce an acoustic impedance (AI) dataset. Comparisons of AI-predicted vs. actual hydrocarbon pore thickness during appraisal drilling have shown a typical variance of less than +/- 10%.

A horizontal appraisal well was spudded in mid-1994. Once the target reservoir was entered, directional information from MWD was used to steer the well along a desired path in real time to intersect specific targets. The hole was completed using a pre-packed production liner. An extended well test using a semi-submersible linked to a shuttle tanker was undertaken, and over 400,000 bbl of oil were produced. This extended test yielded significant long-term development information.

This combination of technologies - seismic, drilling and extended well test - has proved invaluable in advancing the appraisal of Foinaven.

Foinaven Phase I is being developed by Petrojarl IV, a ship shaped FPSO facility. Horizontal production wells will be used with subsea completion, and following processing the crude oil will be exported by shuttle tanker. Development drilling started in November 1994. First oil is programmed for early 1996 at a plateau rate around 85 mbd.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California