Potential environmental considerations associated with shale gas

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 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.

The BGS has 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.

In late 2011 the BGS started a new project to establish the baseline of methane levels in groundwater throughout the UK; preliminary results are due to be published in Summer 2013.

Groundwater monitoring and protection

The BGS has recently started (2011) a baseline study for groundwater methane in areas likely to be prospective for shale gas.

This study will involve sampling groundwater from water wells, and determining concentrations of natural methane and its origin (thermogenic or biogenic).

The results will help us to identify any future impacts on shallow groundwater that might result from fracking or shale gas extraction.

The project is part of a wider national programme of groundwater characterisation that includes:

  • aquifer characterisation and testing
  • chemical, isotope and environment tracer analysis
  • groundwater age dating
  • conceptual model development
  • development of risk screening tools and models

The BGS aslo 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 studies 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.

See also — Blackpool earthquake | 27 May 2011 and Fracking and earthquake hazard.

Contact

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