Use of propane or carbon dioxide could save millions of gallons of fresh water in unconventional gas production
Unconventional gas production has changed the world's energy outlook, but critics point to the large amounts of water required to extract it. Now the push for more natural gas through horizontal drilling and hydraulic fracturing (or "fracking") is leading to new ways to extract it using much less water.
Gasfrac, a company based in Calgary and Houston, Tex., uses a propane-based gel, injecting this rather than water to create the fractures.
Propane has low surface tension, about one-tenth that of water, explains Jim Hill, Gasfrac's president and chief executive officer in Calgary. This enables the liquid to slip more easily into the narrow fissures of a fracking operation. This in turn helps open the cracks in the rock and access more gas than water would allow.
It's a proven yet relatively new technology that was barely possible a decade ago, Mr. Hill says. That's because it requires complex computer calculations to get the right mix − calculations that used to require huge mainframes to crunch the numbers, but which now can be done on your smartphone, he says.
Gasfrac, founded in 2006, has more than 2,000 fracturing treatments to its credit since becoming operational in 2010, most of them in Canada.
Substituting propane for water is significant because there is rising concern about the effects of fracking. The Council of Canadian Academies has just released a long-awaited report that concludes there is not enough known yet about the impact of fracking to declare it safe. The Council is an independent organization that pulls together scientists and experts to provide objective policy-related assessments.
Meanwhile, there is increasing competition for precious water between industry and agriculture. While water use by the unconventional gas sector varies, a typical fracking operation might use 20,000 cubic metres of water as its primary fracturing fluid for just a relatively small section of a fracking operation, according to the Canadian Society for Unconventional Resources (CSUR), an industry umbrella group. That's enough water to grow nine acres (3.6 hectares) of corn in a year.
Unconventional gas production, which accounted for 15 per cent of worldwide production in 2010, is expected to rise to 80 per cent by 2040, so using propane or other materials could save millions of litres of water.
Reducing water usage puts less pressure on supplies and means that less water needs to be treated after fracking, Mr. Gorton adds. Using carbon dioxide also has potential for disposing of this greenhouse gas, potentially helping to curb climate change.
Other companies are working with different fracking fluids. One, Trican Well Service Ltd., has developed fluids that are classified as non-toxic. Trican's fluid, called TriFac-MLT, enables the use of less fresh and more recycled water and is salt-tolerant (salt builds up in fracking water, requiring additional fresh water).
These chemicals still need to be recovered after a fracking operation, but they're not considered a threat to water quality, making the used water easier to treat and restore. Other companies are experimenting with different alternatives, such as using saline water found in deep aquifers in areas such as British Columbia's Horn River Basin. There are a lot of identified saline aquifers in Western Canada; using these would make it unnecessary to tap into fresh water.
It's still unresolved where the saline water would go after fracking. Using deepwater saline is also more costly than using fresh water and adding chemicals, but this could change depending on demand for fresh water from farmers, cities and towns.
There's also potential in sharing water supplies. In Dawson Creek, B.C., Shell Canada opened a water treatment plant near its Groundbirch facility, which has five natural gas processing plants and more than 250 wells. The water plant treats 4,000 cubic metres of sewage water a day − equivalent to 12,000 households − diverting wastewater that was discharging into the creek that runs through the community.
The water, treated to a standard considered suitable for industrial and municipal use, is used by the City of Dawson Creek for cleaning roads and watering sports fields. Shell pipes a share of the water 48 kilometres for its unconventional gas production. This eliminates the need for 3 million trips by water trucks each year as the gas field is developed.
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