Environmental impacts of shale gas extraction

Dr Rob Ward, BGS Head of Groundwater Science, discusses the hydrogeological aspects of shale gas extraction; including water resource requirements, possible groundwater contamination and treatment, well integrity, and the chemical composition of fracking fluids.

Shale gas extraction raises environmental concerns in relation to:

Carbon dioxide (CO₂) and methane (CH₄) emissions, particularly the potential for increased fugitive CH₄ emissions during drilling compared with drilling for conventional gas
the volumes of water and the chemicals used in fracking and their subsequent disposal
the possible risk of contaminating groundwater
competing land use requirements in densely populated areas
the physical effects of fracking in the form of increased seismic activity

The BGS has the expertise and facilities to assess and advise on the risk of shale gas extraction to groundwater supplies, and to monitor groundwater quality and undertake research into groundwater processes.

In late 2011 the BGS started a new project to establish the baseline of methane levels in groundwater throughout the UK. We have been studying naturally occuring methane in UK groundwaters since the 1980s, but there is no UK baseline data on methane concentrations in groundwater from before the onset of shale gas exploitation.

Groundwater monitoring and protection

BGS hydrogeologist Dr John Bloomfield on protecting our precious groundwater resource.

BGS undertakes a range of scientific studies to better understand groundwater-related processes and phenomena in relation to resource use such as shale gas extraction. These include monitoring; aquifer characterisation and testing; chemical, isotope and environmental tracer analysis; groundwater dating; conceptual model development; development of risk screening tools and models.

Selected capability includes:

groundwater quality and protection
- groundwater quality baseline surveys
- assessment of urban, industrial and agricultural pollution
- evolution of groundwater quality in different hydrogeological settings
- groundwater risk, impact and vulnerability assessment tool development

groundwater catchment processes
- flow and contaminant transport in dual porosity formations
- groundwater residence time and age dating
- biogeochemical interactions and transformations
- geochemical interpretation of water/rock interactions

To carry out this work BGS has the following capability:

extensive laboratory facilities for the determination of water, gas and rock chemistry, isotopes, rock mineralogy, rock hydraulic properties/petrophysics and geotechnical properties
expertise in field survey, data collection and innovative sampling techniques
expertise in 3D geology modelling and hydrogeological modelling
modelling groundwater flow, quality and well hydraulics
geophysical techniques (remote sensing, surface and downhole)
GIS capability, particularly in the combination and use of geoscience information and other datasets for planning and development, resource management, aquifer vulnerability, land regeneration and related studies

Fracking and seismic activity

It is well established that fluid injection can induce small earthquakes. Typically, these are too small to be felt.

Monitoring and careful analysis of shale gas fracking is required to help understand any relationship between the injection process and seismic activity.

Contact

Contact Prof. Mike Stephenson for further information or enquiries about BGS shale gas consultancy services