In the environmental debates raging around natural gas and oil drilling in North America, one thing until now has not been in dispute: it takes huge amounts of water to open up reservoir fractures deep underground. However, new technologies developed in Canada, which have been tested in the United States, may offer the energy industry a waterless way forward.
GasFrac Energy Services Inc., based in Calgary, is awaiting a U.S. patent for its liquefied propane gas (LPG) technology, which will eliminate the use of water in hydraulic fracturing (fracking), said Chief Technology Officer Robert Lestz. He explained the "gas fracking" process at the World Shale Gas Conference and Exhibition in Houston on Wednesday.
"Do shale gas completions and water mix?" he asked the audience. "We've heard numerous conversations about that. When you look at the environmental impact, you have to ask, do they mix? Some traditional frack jobs result in only 10% of the used water being recovered. "At the end of the day, is water the best answer or just the answer we know? We wanted to figure out what we were missing."
GasFrac engineers in Canada took a step back to see if they could find the "perfect frack fluid, one that was completely compatible with the formation." The perfect frack job also would result in "ultimate reservoir performance and certainty, economic and environmental performance and be operationally safe."
LPG -- the same thing stored in millions of garages to fire up outdoor grills -- proved to be the one thing that met all of the "perfect" requirements, said Lestz.
"It's a liquid to start with and it stays a liquid," he said. "Post job, it disappears with 90% of fluid recovery. When it flows back, it's completely marketable."
GasFrac is still awaiting a patent in the United States but the gas frack technique has been used about 1,000 times in the last three years by operators that include Royal Dutch Shell plc and Husky Energy Inc., said Lestz. Most of the tests have been conducted in Alberta, British Columbia and New Brunswick, with pilots at a handful of wells in Colorado, New Mexico, Oklahoma, Pennsylvania and Texas.
According to Lestz, LPG also has gotten some support from regulators. The U.S. Environmental Protection Agency and New York regulators -- who are working on stringent regulations that may allow fracking -- consider LPG a "viable option."
Similar to water fracking, propane gel is pumped underground into deep unconventional formations, which in turn creates pressure to crack the fractures and free trapped gas bubbles. And like water the propane gel forces particles of sand and proppant into the cracks to hold them open to allow the gas to flow.
That's where the similarities end. Unlike water, the propane gel reverts to vapor under pressure and heat and returns to the surface -- with the flowing gas -- for collection, reuse and resale. In addition, LPG doesn't bring drilling chemicals, salts and underground radioactivity back to the surface, said Lestz. The "nasties" are left in the ground.
Gas and oil operators aren't equipped to be in the water treatment business or to handle solids disposal, but they do know how to handle LPG, said the GasFrac executive.
"Propane is propane. It has no chemistry and compatibility issues" when a well is being drilled, Lestz said. Gelled LPG "creates a perfect transport fluid. We have the capability to create the geometry we want and the viscosity we need." Because there's "10 times less surface tension," with LPG over water, operators may be able to achieve maximum initial production rates sooner. Meanwhile, water-based frack fluids cause damage near the fracture area because of imbibtion from the water leak-off, he said. "You end up with flowback into the fracture," which makes production less efficient.
As an example, Lestz explained how LPG is being used to fracture gas wells in the Cardium formation at the Wapiti Field in Alberta. The operator has been able to "pump a job half as large and get to four to five times more" gas, he said.
At a cost of about $2-2.50/gallon today LPG "is more expensive than water," he admitted. However, he said it comes down to more bang for the buck.
"Our drilling friends have done a tremendous job, going from using oak rigs to high-end flex rigs...We use more expensive [drill] bits, more expensive mud systems. At the end of the day, we get cheaper wells and more production...Instead of looking at the cost of the frack job, you have to look at the cost of the effective length you get to use. LPG jobs are more expensive but at the end of the day, you have more you get to reuse."
Potential customers have complained about the costs. You might as well say "'vertical wells instead of horizontal wells.' What you end up with is uneconomic wells. Horizontal wells are more expensive. But value is important. LPG gives you more access to the reservoir. It's like going from vertical to horizontal wells."
Asked if LPG could be handled safely on drill sites, Lestz chuckled. On a wide screen he showed photos of how propane today is stored in garages and in backyards. "The U.S. home propane market is huge. Tanks are built so safe that they can take on accidents."
The largest job to date was one million pounds of LPG used on a 10-stage frack job in a 3,900-foot horizontal well, he said.