Summary
The Schiehallion field has experienced many reservoir management challenges
since first production in 1998. Dynamic data such as formation pressures,
pressure-transient analysis, interference testing, tracer analysis, and 4D
seismic need to be interpreted with great care—Schiehallion has examples in
which the data have been invaluable and others in which the data are ambiguous
or misleading. It is essential to integrate several data types to obtain
reliable conclusions. This paper describes some of the highlights and pitfalls
experienced in Schiehallion.
Schiehallion Background
The Schiehallion field is situated on the Atlantic margin of the United
Kingdom Continental Shelf (UKCS), to the west of the Shetland Islands, in water
depths of approximately 400 m (Fig. 1). Together with the smaller satellite
Loyal field, it is produced through subsea horizontal wells tied back to the
Schiehallion floating production, storage, and offloading (FPSO) vessel. The
combination of water depth with strong winds and currents, creating waves up to
30 m high, makes this one of the most hostile environments in the world for
hydrocarbon production.
The reservoir is a deepwater turbidite of Tertiary age deposited in the
Faroe-Shetland basin (Ebdon et al. 1995; Lamers and Carmichael 1999; Mitchell
et al. 1993; Morton et al. 2002) and showing varying degrees of channelization
in different parts of the field (Fig. 2). Permeability is generally good
(approximately 600 md), but the low reservoir depth (2000 m), low gas/oil ratio
(GOR) (340 scf/bbl) and limited aquifer provide little natural energy, so water
injection is critical. Seismic data quality is mostly very good.
© 2006. Society of Petroleum Engineers
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History
- Original manuscript received:
31 May 2005
- Revised manuscript received:
14 April 2006
- Manuscript approved:
17 May 2006
- Version of record:
20 August 2006
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