Oil has been extracted from the Isle of Purbeck since the early 17th century from Kimmeridge in the form of oil-shale.
The oil extraction industry in the area stated in 1936 with experimental oil wells being bored near Kimmeridge and in 1960 BP’s Kimmeridge Oil Field was discovered. The Kimmeridge site has a single beam pump or nodding donkey which has been extracting oil continually since 1961 making it the oldest working pump in the United Kingdom extracting around 65 barrels per day from a depth of 350 meters below the cliff.
The oil is transported by tanker to Wytch Farm where it is piped to storage tanks near Southampton.
Nodding Donkey photo by Huligan0 (https://commons.wikimedia.org/wiki/User:Huligan0) Creative Comons.
Wytch Farm
The Isle of Purbeck is home to the largest onshore oil field in western Europe but most visitors to the area wouldn’t know that the oil extraction field exists due to the careful planning and screening of the site in Rempstone Forest.
The Wytch Farm plant has been extracting oil and gas from sandstone and limestone oil reservoirs in the Wessex Basin since 1979 and is expected to continue until 2037. The oil is extracted using a form of fracking called “water injection” also know as “water flooding”
The oil field is located in a faulted block of Jurassic rock and older rocks beneath the Hampshire Basin and consists of three separate reservoirs known as Bridport, Sherwood and Frome. Bridport which was the first discovery, is in the Jurassic Bridport Sands 900 metres (3,000 ft) below Poole Harbour. The much larger Sherwood (discovered 1978) is below this in the Triassic Sherwood Sands at 1,600 metres (5,200 ft) and extends under Poole Bay. Frome is in a shelly limestone at 750 metres (2,460 ft). The field extends eastwards from Sandbanks and Studland for around 10 kilometres (6.2 mi) under the sea to the south of Bournemouth. (source https://en.wikipedia.org/wiki/Wytch_Farm)
At its peak 110,000 barrels per day was being extracted at Wytch Farm and is now extracting 50,000 barrels per day.
Exploring for additional oil reserves in 2019
In 2019 Corallian Energy were granted a license for drilling off the coast of Studland and Poole Bays to try to locate additional oil reserves in the Sherwood Sandstone of Triassic age rock below the sea.
The temporary oil platform was located 4 miles off Studland Bay in February 2019 and planed to drill to a depth of approximately 1,850 metres below sea level.
If oil is found it will be extracted with new horizontal wells from Wytch Farm Oil Site
On the 25th February 2019 the Colter well (98/11a-6) had been drilled as a vertical well with the Ensco-72 jack-up rig and reached a Total Depth of 1870m MD in the Sherwood Sandstone. Oil and gas was found with an estimated a mean recoverable volume of 15 mmbbls (Million Barrels).
Additional Information
Southampton University have very detailed information about the petroleum geology of the area on southampton.ac.uk