Cuadrilla's estimate for shale gas in Lancashire's Bowland basin cannot be trusted

Posted by Tim Probert

The British Geological Survey (BGS) is working on a new estimate of the amount of shale gas in Lancashire’s Bowland Basin after suggesting Cuadrilla Resources’ figure of 200 trillion cubic feet (tcf) – enough to meet national natural gas demand for 56 years – could be flawed.

Head of energy Mike Stephenson said it is impossible for the BGS to verify the accuracy of Cuadrilla’s estimate for ‘gas in place’ in a 500 square mile area of Northwest England, as the Lichfield-based shale gas developer has not yet submitted its methodology for calculations. Concerned Cuadrilla’s estimate is inaccurate, the BGS is now conducting its own survey, which it hopes will give a clearer indication of how much shale gas is recoverable.

“As far as I’m aware, Cuadrilla has not given a clear methodology for the basis of their calculations,” says Stephenson. “We are working on a new figure with a volumetric basis for the calculations, so we will come up with a much more accurate figure shortly”. The BGS’ official estimate of the potential resource of the Bowland shale is 4.7 tcf, significantly less than this September’s announcement by Cuadrilla, the only company in the UK to have drilled for shale gas to date.

Speaking at this week’s Shale Gas Environmental Summit in London, Stephenson stated: “We worked out our old resource figure for the Bowland shale, somewhat crudely, by comparing the recovery rate for Barnett shale in Texas, which is the same geological age, and multiplying it by the land area of Bowland. Cuadrilla’s estimate of 200 tcf is about 40 times higher.

“I’m not knocking Cuadrilla’s estimate because they have gas yield data from their two wells whereas we have none, because no-one has drilled shale gas wells in the UK,” he added.

Earthquakes no headache?
Cuadrilla halted shale gas drilling operations in May after two small earthquakes near Blackpool. The Department of Energy and Climate Change (DECC) was tight-lipped over when it would make a decision on whether to allow Cuadrilla to resume exploration in the Bowland basin near Blackpool. “We will take our time,” a DECC spokesman told Millicent Media.

Commenting on Cuadrilla’s report submitted to DECC on 2 November, which concluded a link between hydraulic fracturing, or ‘fracking’, and the earthquakes was “highly probable”, Stephenson said the BGS was not unduly concerned by the shale gas developer’s assertion that “the theoretical maximum seismic event of magnitude 3 would not present a risk to personal safety or damage to property on the surface”.

“Earthquakes of magnitude 3 may cause things to fall off shelves, but in our experience they can’t be felt by human beings,” he said. “They are probably too small to cause damage.”

Stephenson said the lack of peer-reviewed research into shale gas fracking, particularly the potential contamination of water supplies, was of great concern to the British authorities. Only two peer-reviewed reports have been conducted into methane leakage and their conclusions are viewed as highly questionable by most geologists, he said.

The BGS and the Environment Agency now intend to conduct a baseline study into the impact of fracking and potential methane contamination of groundwater. “We want to determine the background levels of methane in groundwater before anybody fracks so that any other methane found can be attributed to fracking,” explained Stephenson.

“It’s very important to do a baseline study. It can be done quickly, it’s just a case of measuring wells and the amount of methane in them. It’s a priority, but it doesn’t need to stop the fracking process.”