Gas fields in Colorado soon may serve as a laboratory for testing a different way to fracture shale rock formations – one that doesn’t pump millions of gallons of water underground or yield contaminated wastewater.
Testing liquid nitrogen for fracturing
Even as environmentalists rekindle efforts to ban hydraulic fracturing in the state, petroleum engineers in Colorado are working out the kinks in a process called cryogenic fracturing, which replaces water with searing cold liquid nitrogen or liquid carbon dioxide.
Fracturing with water has turned the United States into one of the biggest energy producers in the world.
Scientists at the Colorado School of Mines in Golden hope that the ultra-cold thermal shocks that occur when liquid nitrogen meets shale rock will have a similar effect as water, creating enough stress to crack open the subterranean stores of oil and gas.
Swearing off water could calm some of the environmental opposition to fracturing.
And because the liquid nitrogen would evaporate underground, cryogenic fracturing could form bigger canals for oil and gas to flow through than water-based fracturing, boosting oil and gas production.
“Essentially, some shale absorbs water very quickly, and the entire formation swells in size and closes up any pathways,” said Kent Perry, vice president of onshore programs at the Research Partnership to Secure Energy for America, which administered a $2.6 million Department of Energy research contract for the project.
“When you’re using water in shale formations, even where you’re successful with the development, recovery is still low, and part of that is water trapping.”
In concept, cryogenic fracturing works like hot water pouring onto a frozen car windshield – producing a sharp temperature change that can crack the glass.
In practice, liquid nitrogen or liquid carbon dioxide would be poured down a well through steel or fiberglass tubing as a fracturing fluid, in place of the water that typically is blasted underground along with chemicals and sand or man-made proppants to hold the fractured rock apart.
It’s a spin on fracturing experiments with gaseous nitrogen that oil companies tried in the 1970s and 1980s, with disappointing results, and a follow-up to more recent attempts with liquefied nitrogen that proved too costly.