Central to Cuadrilla’s protection of the environment is the prevention of water contamination. However, in the industry, such incidents have been extremely rare.
In the US, it is possible that bad practice by a very small number of operators may have led to some isolated and short-term incidents of natural gas contaminating water. However, these practices are the exception out of the hundreds of thousands of producing wells in the US. By running three strings of casing lined with cement hundreds of feet below the aquifer, Cuadrilla is able to prevent gas migrating from the well bore into the aquifer.
One of the main questions concerning water is how we can prevent contamination of the aquifer and ground water.
Throughout Cuadrilla’s operations, robust safety measures are in place to protect the environment. Cuadrilla’s wells are all designed with at least three layers of steel casing – the surface casing, the intermediate casing and the production casing. The intermediate casing ensures that there can be no leakage path from the shale reservoir up to the aquifer. These are inspected by an independent well examiner before being sent to the HSE for review.
In the US, only a handful of operations have led to the subsurface environment being contaminated with natural gas, with bad well design the cause – not hydraulic fracturing. Cuadrilla always uses an intermediate casing as part of its well design. In the US, this was recently made a requirement by New York as part of the state’s recommendation to allow fracturing to resume.
We sometimes also get asked if water can be contaminated as a result of hydraulic fracturing.
There are two reasons why fracturing fluid remains in the shale rock, even in the presence of a fault:
- There is no pathway for fluid to travel along. Natural and hydraulic fractures do not extend up to the aquifer.
- Above the shale lies the Manchester Marl, a thick impermeable rock forming the ‘regional seal’. We know the Manchester Marl is impermeable to water as it has sealed the gas in the shale for hundreds of millions of years.
A report for the Society of Petroleum Engineers has made this clear:
Downhole environmental risks to fresh water supplies from fracturing in shale development greater than 500ft below the water sand is literally as close to zero as can be established from engineering analysis using the reported and documented results available from at least 10,000 shale wells covered by the literature and searched for this paper.
Thirty Years of Gas Shale Fracturing: What Have We Learned?, Society of Petroleum Engineers, 2010
During site preparations, a thick impermeable membrane is placed across the entire site which prevents any potential spills leaching into the groundwater. The membrane holds all site surface water which is also tested prior to disposal