Buchan Oil Field - Development

Development

The initial lifetime of this field was five years with a production of 50 million barrels (7,900,000 m3) oil, so to maximize profit the development had to proceed very quickly and all capital costs be kept to a minimum (Mieras 1983). For this reason a lot of the development was done in parallel so that the wells, pipelines, and offshore loading buoy were all completed in time. Since the drilling had been fully completed and then capped the previous autumn, when the rig was available to come on-line it was almost able to reach full reservoir production capacity immediately. The biggest delay came from the conversion of a semi-submersible drilling rig, Drillmaster, to a production rig, which ended up 20 months late and 40% costlier than first envisioned (Mieras 1983). These retrospective upgrades were necessary after a similar rig, Alexander L. Keilland, collapsed and killed 100 people.

Production of the Buchan Oil field came on-line in May 1981, and oil export initiated in June 1981. Initially oil was offloaded from the platform to a tanker. However in 1986 a pipeline was built which connects with the Forties pipeline system and then to Cruden Bay. This pipeline added a further 15 million barrels (2,400,000 m3) to the recoverable reserves.

Production peaked soon in 1983 with an average of 32,000 bbl/d (5,100 m3/d), but in late 1984 production was declining, and the rig underwent a major maintenance programme along with an addition of gas lift facilities. Unlike most fitting of gas lifts causing long delays in production, the need for a gas lift had been anticipated and so was able to be completed via wireline intervention (Pinchbeck 1979). The addition of the gas lift allowed production to reach 20,000 bbl/d (3,200 m3/d) for several years before beginning a slow steady decline in 1989. Any remaining gas is flared.

Reserves for the field, though, were continually upgraded from the cautious prediction of 50 mbo in 1979 to 134 mbo in 2002. This was put down to increased knowledge of the field as well as improvement in extraction methods.

BP continued to be the principal operator of the field alongside Texaco, which had been awarded the 20/5(a) block. This continued until August 1996 when the field was sold along with the Beatrice Oil Field and Clyde Oil Field fields to Talisman Energy, a Canadian oil company that specialises in fields that are nearing their abandonment stage. As of 2002 the field was thought to still have a further 37 million barrels (5,900,000 m3) of recoverable oil. Due to advancements in technology and better understanding of the field, the final size of the recoverable reserves is thought to be 155 million barrels (24,600,000 m3) oil.