The oil field takes its name from the neighbouring Wytch Farm which had existed on the site for many centuries on the fringes of Wytch Heath.
Pre-1973
The earliest industry in the Wytch Farm area dated to the early medieval period and featured multiple salt production workshops. The workshops, adjacent to the modern oilfield, were part of a medieval salt industry owned by Milton Abbey. The site was excavated by Bournemouth University under the directorship of Dr Derek Pitman. The Isle of Purbeck's oil shale, or "Kimmeridge Coal" which has been won from the cliffs to the east of Kimmeridge since the early 17th century, is no longer used commercially. Similar deposits were found at Wytch Farm in the 1890s, but were commercially exploited until only circa 1900, and only at a low level. The Kimmeridge Oil and Carbon Company reported that in 1890 it had dug of tunnels at Kimmeridge on four levels into the local cliffs. There was a local jetty to export the oil shale, and smaller operations occurred at nearby Bencliff Grit east of Osmington Mills. The Isle of Purbeck's oil industry began in 1936 with the first unsuccessful and then experimental wells drilled at Broad Bench near Kimmeridge by D'Arcy Exploration. The area had long been mined for oil shale and tar, but was only prospected for crude oil in the 1950s. It was not until 1959 that a borehole at Kimmeridge showed that oil was seeping out, and 1960 that British Petroleum's Kimmeridge Oil Field was discovered.
1973 to date
The field was discovered by the nationalised British Gas Corporation in December 1973 and began producing oil in 1979. As part of the privatisation of British Gas in the 1980s, Wytch Farm was sold to BP which took over as operator in 1984. In May 2011, BP announced that it had agreed to sell its majority interest in Wytch Farm to Perenco, which became the new operator. Premier Oil has a 30.1% stake in the field. On 17 May 2011, BP announced the sale of its interests in the Wytch Farm, Wareham, Beacon and Kimmeridge fields to Perenco and the sale of the Dimlington gas terminal to Perenco in February 2011. In September 2012, Perenco UK applied to Dorset County Council for permission to extend the life of 39 planning permissions at three of the oilfields. DCC’s Planning Committee recommended approval of the applications on 6 September 2013, thereby extending to 2037 the operational life of the oilfields, beyond their original end-date of 2016.
Geology
The field is located in a faulted block of Jurassic and older rocks beneath the Hampshire Basin, close to the steeply sloping monocline in the overlying chalk. The Purbeck Monocline defines the field's southern limit. The field consists of three separate reservoirs known as Bridport, Sherwood and Frome. Bridport, the first discovery, is in the Jurassic Bridport Sands below Poole Harbour, with an oil source in the Lower Lias. The much larger Sherwood is below this in the Triassic Sherwood Sands at and extends under Poole Bay. Frome is in a shelly limestone at. The field extends eastwards from Sandbanks and Studland for around under the sea to the south of Bournemouth.
Production grew from in 1984 and eventually peaked at in 1997; by 2002 this had declined to. In 2002 it was estimated that the field contained reserves of 65.40 million tonnes of oil, 4.73 million tonnes of natural gas liquids and of natural gas that will last until 2020 and 2025 respectively. Oil is also transported to Wytch Farm for processing from two smaller Dorset oilfields, Wareham by pipeline and Kimmeridge Oil Field by road. Oil is piped about from Wytch Farm via Fawley to a terminal on the far side of Southampton Water at Hamble, for export by tanker. Natural Gas is piped to Sopley, north of Christchurch, for use in the national domestic gas supply network. Smaller quantities of liquefied petroleum gas are transported by road. A rail terminal at Furzebrook connecting to the Swanage Railway between Corfe Castle and Wareham is now closed and mothballed.
