Compared to other fossil fuels the overall water use intensity of shale gas is low and claims by some opponents that the shale gas industry represents a threat to the security of public water supplies “is alarmist”, according to the UK’s Chartered Institution of Water and Environmental Management.
However, the organisation warns that, given the large quantities of water required at the beginning of the life of a production well, this could have local impacts for catchments and water sourcing.
Despite the wide variation in the estimates of water use in the different stages of shale gas production CIWEM says this still allows certain conclusions to be drawn.
It suggests that, at the exploration stage, water demand during a shale gas hunt is “not likely to be significant” compared to other users and that it is likely that operators will continue to source water on a site by site basis depending on the closest source and ease of connectivity.
But CIWEM warns: “Should a large industry develop in a small geographic area there could be local or regional consequences. The industry will have to compete against different users and should there be any temporary water use restrictions put into place, it could in theory be affected.
“Taking a regional scenario the water required by the industry is comparable to other industrial users and would face the same drought restrictions.
“If water companies have the available resources and there is a close mains connection this is possibly the easiest option; tankers may also be used.”
CIWEM considers operators should provide a profile of water use and flowback over life of the shale well to help establish any pinchpoints in supply.
It says too that where there is overlap between water stressed catchments and shale gas licence areas, operators will need to be aware of the risk that there may be smaller volumes available in the future.
“Drilling and fracturing processes may have to be timed as to when volumes of water are available.”
CIWEM points out that a recently forged memorandum of understanding between UKOOG (UK Onshore Operators Group) and agency Water UK should assist in planning water resources in the future for the industry.
It recommends that water and sewerage companies should become statutory consultees in the planning process.
CIWEM is clear that, if shale gas resources are to be developed safely in the UK, ensuring due regard for protection of the wider environment, exploration should not be permitted in areas where there is a genuine risk to valuable drinking water resources located in groundwater.
“Groundwater including any local aquifers should be carefully delineated by the operator as part of the well design and fracturing risk assessment process,” it says in newly published research.
“The mapping of the relationship between potential shale gas source rocks and principal aquifers should be used to assess applications with strong enforcement by the Environment Agency through planning or permitting controls to protect groundwater.
“This would help to minimise the risks from the mobilisation of solutes or methane in areas of natural faults or in areas of shallow shale plays.”
This is clear acknowledgement that water resources may indeed be polluted as a result of shale gas exploration and extraction activities
However, CIWEM states that contamination of aquifers from mobilisation of solutes and methane is “unlikely” where shale plays exist at depth in the UK.
It reiterates the British Geological Survey view that such contamination is “unlikely to occur if shale gas exploitation is restricted to depths greater than 1,500m”.
But CIWEM admits: “Where the source rocks are shallower there could be a greater risk and companies will have to ensure that fracture sequences are monitored using performance standards. Fracturing operations should be examined as part of the well examination arrangements.”
It admits too that contamination of soil, surface or groundwater from spills of returned waters “is a considerable hazard”.
As for storage and management of fracking fluids and wastes, CIWEM point to a Massachusetts Institute of Technology review of 10,000 wells, which found that of 43 pollution incidents related to natural gas operations, 50% were related to the contamination of groundwater due to drilling operations and 33% due to surface spills of stored fracking fluids and flowback water.
“Appropriate regulatory control is needed to ensure returned waters are appropriately contained, managed, and treated prior to eventual disposal,” adds CIWEM.