Natural gas producers restricting fresh water use by David Pryce, October 4, 2012, Vancouver Sun
Water is essential to the recovery of natural gas from conventional and unconventional sources, such as shale rock. It is needed to drill and complete a well. Once that is done and the well starts producing for the next 20 to 30 years, it is rare water has to be used again. Drilling a well into a reservoir that is relatively easy to access, called a conventional reservoir, requires about 400 to 600 cubic metres of water. About 86 per cent of Canada’s natural gas production comes from conventional wells. As conventional reservoirs are gradually depleted, industry is shifting its focus to natural gas resources trapped in unconventional reservoirs. That’s the case in British Columbia, home of the Horn River and Montney plays, which are among North America’s most promising unconventional natural gas fields. Unconventional resources are developed by drilling horizontal wells into the shale formation, typically 2,000 to 3,000 metres deep. After the well is drilled, the horizontal leg of the well is hydraulically fractured to get the gas to flow to the wellbore and from there to the surface. This process requires between 5,000 and 110,000 cubic metres of water per well.
CAPP’s Hydraulic Fracturing Operating Practices, released in January 2012, specifically address this issue and commit natural gas producers to reduce their reliance on freshwater and recycle water as much as practical. Alternatives to freshwater include brackish groundwater drawn from slightly saline aquifers that typically sit below freshwater aquifers, or deep saline groundwater. Reclaimed municipal waste water is another alternative.
An example where this is put into action is the Debolt Water Treatment plant, a joint venture between Encana and Apache Canada in the Horn River Basin. The plant – the first of its kind in North America – treats saline groundwater from an aquifer 700 metres below the surface for use in hydraulic fracturing operations. This has led to a drastic reduction in the volume of freshwater needed in both companies’ hydraulic fracturing operations.
Recycling water for reuse is another option to reduce fresh water use. Flowback, which is the water and a very small amount of additives injected into the well during hydraulic fracturing that flows back to the wellbore, can also be reused for hydraulic fracturing.
In 2010, CAPP members voluntarily reported on water reuse in Western Canada shale and tight gas plays for the first time. Based on the data received in 2010, four per cent of water was reused in these projects. Industry recognizes the level of reuse must be improved and is advancing a number of initiatives to address this issue. Water reuse reporting has become mandatory this year, and more complete and comprehensive data will be released at the end of the year. [Emphasis added]
AEA: Support to the identification of potential risks for the environment and human health arising from hydrocarbons operations involving hydraulic fracturing in Europe “A proportion (25% to 100%) of the water used in hydraulic fracturing is not recovered, and consequently this water is lost permanently to re-use, which differs from some other water uses in which water can be recovered and processed for re-use.”
The National Energy Board’s 2009 Primer for Understanding Canadian Shale Gas – Energy Briefing Note
“remembering that production declines in shale-gas are steep and within just a few months, production should be significantly less”
“Flow-back water is infrequently reused in other fracs because of the potential for corrosion or scaling, where the dissolved salts may precipitate out of the water and clog parts of the well or the formation.”
“Drilling and hydraulically fracturing wells can be water-intensive procedures; however, there is very limited Canadian experience from which to estimate potential environmental impacts.”