Persistence and a Creative Facility Solution Enable Successful Development of Stranded Offshore Gas

Abstract

Summary The F3-FA field is a small, offshore gas field in the Dutch sector of the southern North Sea. The discovery well drilled there in 1971 located rich gas in the Jurassic Scruff Greensand (SGSS) formation; however, its constrained size meant that field appraisal could not take place for another decade, with two wells drilled in 1982. Following appraisal, the field struggled to compete for investment capital and pipeline access against other development opportunities. Ultimately, the original operator exited the field in 2008, and Centrica Energy purchased its equity and field operatorship. A different opportunity set allowed Centrica and its partner EBN to advance the field development. Uncertainty regarding the dynamic performance of the field and recognition of its limited volumes, and, therefore, limited producing field life, led to the adoption of a self-installing platform (SIP). The platform is currently the largest of its kind in the world at 133 m high, being slightly heavier than the Eiffel Tower and designed for future reuse at another location for the purpose of producing some other small accumulation. The platform was installed in September 2010, with full processing and compression facilities in place, and tied into the northern offshore-gas-transport (NOGAT) pipeline system. Production is from a single, near-horizontal production well. The well design called for drilling across two fault blocks with potentially different fluid charges and pressures. The reliance on a single development well reflected the marginal nature of the development, with a range of reserves that reflected uncertainty about gas distribution and the dynamic behavior of a reservoir that did not have any analogs to draw on. First production was achieved in January 2011, and, to date, the field has performed strongly, with no indication of the aquifer influx that was an uncertainty going into development. The condensate yield has also proved to be much higher than anticipated. The prolonged time between exploration and first production is a familiar trait for many small developments in recent years in the southern North Sea, often executed by a new breed of operator. This length of time is also typical of the choices needed to bring such fields to production, given modest reserves and unresolvable subsurface uncertainties.