A dispute has broken out between the company that undertook the UK’s only fracking operation and commentators over whether the wellbore has begun leaking.Â
Emails obtained by Vice News between Cuadrilla Resources, a UK oil and gas exploration company, and the Health and Safety Executive (HSE) seem to show that the decommissioned fracking site has issues with what the oil industry refers to as "sustained casing pressure".Â
The Preese Hall well in Lancashire seems to have suffered a "loss of integrity", implying a possible leakage of shale fluid and gases. Cuadrilla has denied that this is what the emails suggest, and a spokesperson for the company stated that "the well integrity at Preese Hall is secure and always has been".Â Â
Vice News said there was no evidence of any leakage outside the wellbore’s casing.Â Â
However, Anthony Ingraffea, a professor of engineering at Cornell University, told Vice News: "It is quite apparent … that there was indeed a loss of wellbore integrity followed by attempts to remediate."Â
An HSE spokesperson said: "Some may interpret increased pressure in the annulus as a well integrity issue. The pressure increase in the annulus was well within the design parameters and does not constitute a risk to the health and safety of people; therefore it was not reportable to HSE.Â
"There was no leak of fluids from the well and the issue has been resolved during the abandonment process. HSE inspectors will continue to monitor the situation."
Caroline Lucas, a Green Party MP, has said that the emails have "cast serious doubt" on the government’s assurances of the safety of fracking.Â
The site at Preese Hall is no longer in use after two earthquakes occurred that were thought to be a result of its operations.Â
The growth of fracking in America has caused levels of natural gas production to rise to their highest in history. However, the drilling has become controversial owing to concerns about the health and safety of those living close to the sites.Â
Mark Walport, the UK’s chief scientific adviser, said in government-commissioned report that fracking was akin to Thalidomide, tobacco and asbestos in terms of danger to the public.Â
The build up of annular pressure in wellbores is a common occurrence in the oil and gas industry. A recent report by SINTEF, the Norwegian scientific research organisation, found that between 40% and 50% of wells in the North Sea and the Gulf of Mexico had integrity problems.Â
Andrew Wojtanowicz, a professor of petroleum engineering at Louisiana State University, said: "About 90% of wells have casing that are able to contain the pressure, but the remainder pose a significant pollution risk through leaking hydrocarbons into the sea or into aquifers beneath it, and regulators such as Norway’s Norsok require pressure to be monitored continuously."