The UK onshore oil and gas industry is committed to working with regulators and within local areas to ensure that any activity is done safely and with as little impact to the environment as possible. Throughout our operations and the lifecycle of our wells robust safety measures are in place to protect the environment.
Protection of aquifers and ground water is essential. IGas wells are all designed with the minimum of 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.
The main UK legal regulations covering well design, construction and decommissioning are:
• Offshore Installations and Wells (Design and Construction etc.) Regulations 1996 (“DCR”);
• Borehole Sites & Operations Regulations 1995 (“BSOR”);
• Dangerous Substances and Explosive Atmospheres Regulations 2002 (“DSEAR”); and
• Provision and Use of Work Equipment Regulations 1998 (“PUWER”).
(For further information read the UK Onshore Shale Gas Well Guidelines here)
Prior to any drilling activity, we must send our proposed well design to an independent well examiner. Once the design has been satisfactorily assessed by the examiner, we must then notify the HSE of the well design and operation plans. The HSE carries out its own review of these plans, taking into account any comments or recommendations made by the independent well examiner.
The design and construction of the well is key to subsurface environmental protection. Through the use of multiple physical barriers of casing and cement, as well as utilising natural impermeable geology layers as protection, the well will protect any migration of hydrocarbons or well fluids into the surrounding rock formation.
During site construction, a thick impermeable membrane is placed across the entire site which prevents any potential spills leaking into the groundwater. The membrane holds all site surface water which is also tested prior to disposal.
The EA, which regulates shale extraction, has investigated the likelihood of groundwater contamination in detail and judged that the environmental risks at each individual stage of exploratory shale gas operation, after proper management and regulation, are “low”*. The EA will not permit activities if they are close to drinking water sources, such as groundwater from aquifers.
According to a joint Royal Society and the Royal Academy of Engineering report the risk of water contamination is very low provided that shale gas extraction takes place at depths of many hundreds of metres or several kilometres – which would be the case in the UK**.
The Chartered Institution of Water and Environmental Management (“CIWEM”) also agree that risks to groundwater quality are generally considered to be low in the UK where the shale rock in question often exists at considerable depths below aquifers and gas would be required to migrate many hundreds of metres between source rock and sensitive groundwater***.
Remediation and restoration
As a responsible operator, we ensure our old sites are remediated to the highest standard. An example of this is the restoration carried out this year at our Egmanton site. Once the site of the Egmanton oilfield Central Gathering Station, we have removed all the plant equipment and machinery, including pipelines. In agreement with the landowner and Planning Officers, the land was restored to a mixture of woodland, grassland and wetland. The work is now complete and wildlife has already started to colonise the new habitats that have been created.
Watch the EA video on shale gas industry regulation here.
Watch the HSE videos on developing shale oil and gas in the UK here.