The fracking company, Cuadrilla, has dismissed fears that shale gas in the Fylde area of Lancashire would contain large amounts of hydrogen sulphide, a hazardous gas associated with the smell of rotten eggs.
Concerns were raised earlier this month in a report by the geologist Robin Grayson on the website Researchgate.
He said there was a culture of secrecy about hydrogen sulphide (H2S) in gas in the Fylde and there were proven examples in the shales in Lancashire.
Mr Grayson said gas with high levels of H2S, known as sour gas, was also produced from shales under the seabed off Lancashire, Merseyside and North Wales and then treated at Rampside and Point of Ayr.
He said drilling for sour gas was dangerous and local communities should have been informed by companies and regulators. He said:
“All drilling should cease immediately on grounds of public safety and the need for Parliament and enforcement agencies to investigate the large mountain of evidence.”
But in a live webcast this afternoon, Cuadrilla’s commercial director, Laura Hughes, said there was no sour gas at Preston New Road:
“That has been found in reservoirs offshore in the east Irish Sea and across the globe.
“There’s no indication that we have hydrogen sulphide, there’s no indication that we have sour gas here in the Bowland Shale. That’s both in this well and the data that we’ve got from historic wells.
“So there’s no sour gas here.”
The 50-minute webcast, the third organised by Cuadrilla from its Preston New Road shale gas site, was watched by about 80 people at any one time.
Ms Hughes said Cuadrilla expected gas to be released from the Preston New Road wells in the middle of 2018 after the company finished drilling two horizontal wells.
She said a vertical pilot well had almost reached the target depth, more than 2km below the surface. The company had collected core samples of rock, which would be analysed on the site and in specialist laboratories.
“Drilling is going very well. We are getting the information we need.”
The webcast heard there were currently about 30 people on site, split between Cuadrilla employees and contractors, working on the well and on testing the samples.
Ms Hughes said the company would be looking at how fractures created by the fracking process would spread through the shale rock. She said the rock properties would vary throughout the shale layers. The company was looking for the sweet spots, she said.
“Which layer will see horizontal drilling will be decided by mechanical qualities of the rock and quality of the gas in the formation.”
“It’s all about the geology.”
Ms Hughes said Cuadrilla planned to drill horizontally for about 1km from the Preston New Road wellhead westwards towards Blackpool.
She described horizontal drilling as “perfectly safe” and said “there will be no interaction with local properties.”
The well at a depth of 2km would have a diameter of 6 inches, she said.
Ms Hughes didn’t indicate how many wells might be drilled from Preston New Road but she said:
“The idea is that you would have one location that you would be drawing gas from a wider area of the sub surface so it lessens the surface impact.”