Impacts on groundwater quality from abandoned hydrocarbon wells
A study looking at the potential impact on groundwater quality from abandoned oil and gas wells.
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Evidence from the USA suggests that hydrocarbon wells, including shale gas wells, have had an impact on some shallow groundwater. There is a general consensus that a failure of well integrity, or poorly constructed wells, is the main cause of subsurface leakages.
Over 2,000 onshore deep wells have been drilled in the UK for hydrocarbon exploration or production since 1900. Approximately two thirds of these have since been decommissioned in line with regulations and guidance in place at the time, leaving them in a safe state, often described as ‘abandoned’ by the industry. Although there are currently no reports of groundwater pollution from these wells, there is some evidence of limited methane emissions to air from an earlier study of abandoned wells carried out by the Environment Agency and experts from the University of Durham (project SC140032).
The British Geological Survey and the Environment Agency identified where abandoned wells had boreholes nearby that could be used to monitor groundwater quality. Two former oil wells and 2 former gas wells were selected for field monitoring. No pollution was found that might be related to leakages from the oil and gas wells.