The British Geological Survey (BGS) suggests in a new joint report with the U.K. Department of Energy and Climate Change that the Weald Basin in southeastern U.K. could contain between 2.20 Bbbl and 8.57 Bbbl of shale oil.

The range represents the degree of uncertainty over the reserves base; however, in a news release the BGS says the central resource estimate is 4.4 Bbbl.

But no significant shale gas resource is recognized in the region since the Jurassic shale in the basin is not thought to have reached sufficient geological maturity for gas generation.