UK Oil & Gas Investments PLC says analysis of a new well in the Weald Basin indicates there may be as much as 158 million barrels of oil per square mile in the region. That suggests the entire basin may hold as much as 100 billion barrels of oil, more than 10 times earlier estimates. By comparison, Britain has pumped about 42 billion barrels of oil from the North Sea over the past 40 years.
While oil companies have been drilling in the Weald Basin since the 1930s, UK Oil & Gas says new "concepts, techniques and technology" have given it a better understanding of the region's potential. As recently as December, the British Geological Survey issued a report suggesting the basin's shale rock formations held up to 8.8 billion barrels of oil.
Stephen Sanderson, the CEO of UK Oil & Gas, said the latest estimates shows this is a "world class potential resource."
The U.K. has identified three potential reservoirs of onshore oil and gas as it seeks to get in on the shale oil boom that has made the U.S. the world's top energy producer. While U.S. developers have relied on hydraulic fracturing, or fracking, to break up the shale and release energy deposits, UK Oil & Gas says the Weald Basin is "naturally fractured" and so can be tapped using conventional drilling techniques.
But Alastair Fraser, a professor of petroleum geoscience at Imperial College London, warned that the area's geology is "rather unfriendly." While the oil may exist, it will be difficult to get out of the ground because the rocks are extremely tight and non-permeable, said Fraser, who worked for British oil producer BP for 30 years.
"That's all very well," he said of the increased estimate of the basin's oil resources. "But you've got to get at that."
Experts agree that only a fraction of the oil in shale rock formations can be extracted.
Developers have been able to recover from 3 percent to 15 percent of the oil present in areas that are geologically similar to the Weald Basin, Sanderson said.
Another complication may be opposition to large-scale drilling in a basin that stretches across 4,180 square miles (10,825 square kilometers) of southern England.
"Some of the most prospective plays are in environmentally sensitive areas, in National Parks, Areas of Outstanding Natural Beauty or under towns and villages," the British Geological Study said in its report. "Shale oil exploration and potential development should progress cautiously to ensure the activity is safe and the environment is properly protected."