The silica solution
A “what-the-heck” experiment by a leading energy company in western Colorado’s Piceance Basin is paying off with big cost savings and elimination of a newly emerging health concern for oil and gas workers.
The endeavor by Encana USA also is challenging one of the basic tenets of the process of hydraulic fracturing, the practice that has unlocked the basin’s natural gas resource.
Hydraulic Fracturing 101 holds that to develop that gas, and oil and gas reserves in many states, companies inject a mix of water, chemical additives and sand into wells under high pressure to create fractures that are kept open by the sand that’s left behind.
Now Encana is rewriting the book on fracturing, at least in the sandstone formations where most Piceance gas development occurs. It has eliminated the sand and found it doesn’t harm well productivity. The company is careful to emphasize that the approach wouldn’t likely work in a lot of situations, such as in emerging oil and gas development in shale formations in several states, including in Colorado and specifically the Piceance. Still, Encana’s determination that it doesn’t need sand or a similar proppant in its Piceance sandstone formation wells is turning heads.
“Interesting. Wow,” said Jeremy Boak, an assistant research professor at the Colorado School of Mines.
“Wow,” agreed Frank Smith of the Western Colorado Congress citizens group.
“It kind of goes against the traditional thinking,” concedes petroleum engineer Mark Balderston, Encana’s well completions supervisor in the South Rockies.
“It was just what the heck,” he said. “We really wanted to just see if we could save some costs.”
It has done that, saving an estimated $300,000 per well now that it no longer has to deal with the logistics of using about a million pounds of sand per well. Those logistics include the average 500 truck trips that are required to deliver that amount of sand and add to the impacts of gas development.
But a significant side benefit has been doing away with the health issue surrounding frack sand use.
The silica factor
That issue arose almost incidentally as the National Institute for Occupational Safety and Health began looking into potential chemical hazards for workers at fracking sites and kept noticing airborne sand during the substance’s handling. Fracking sand contains up to 99 percent silica, according to NIOSH and the Occupational Safety and Health Administration. Breathing silica can cause silicosis, which depending on the exposure level can lead to chronic lung damage or death.
Working with industry partners at 11 sites in Colorado and four other states, NIOSH found that of 116 air samples, 47 percent exceeded OSHA’s regulatory limit for silica exposures, with 9 percent being at least 10 times that limit.
“We’re quite concerned about it and the levels that were being reported were really off the charts,” said Peg Seminario, director of safety and health for the AFL-CIO.
NIOSH and OSHA put out a hazard alert on the issue, and the industry responded, including Encana. Prompted also by its own studies about the potential silica risk, Encana had contractors make equipment modifications and established protocols to better protect workers.
“It was definitely an issue and something we took seriously,” Encana spokesman Doug Hock said.
Silica dangers also are a concern in places where sand is mined for fracking use, although that mining also has been one of the economic side benefits of the nation’s drilling and fracking boom.
For Seminario, it’s a welcome development that in some cases a company can do away with the sand use altogether.
“Certainly that is actually the number one preferred method in dealing with a hazard, is to try to eliminate it. I think that’s terrific news that they’ve been able to do that,” she said.
The danger of silica at frack jobs also has concerned some people living near drilling. In 2011 Battlement Mesa resident Dave Devanney videotaped frack sand blowing from a well pad near the Parachute Town Hall.
Ursa Resources owns oil and gas leases in the unincorporated community of Battlement Mesa. When told of what Encana is doing, Devanney said it would be one of the things residents will bring up with Ursa as it makes plans to drill there.
A gradual reduction
For Encana, the move away from sand was a gradual and somewhat incidental one.
Because of sand’s logistical challenges, as Encana began using more water to frack some wells, it decided not to add proportionally more sand. Balderston said the change didn’t harm production, and Encana began cutting sand back to such insignificant levels that the company finally determined there was no sense bothering with it at all. In pretty much all the Piceance wells it has drilled starting last year it hasn’t used sand, Balderston said. It drilled about 175 wells in the Piceance last year.
Hock noted that a lot of the sand Encana had been using during fracking was returning back up the well during flowback operations.
“That told us maybe we don’t even need to do this,” he said, in reference to sand use.
Some other forms of proppants, such as ceramic particles, sometimes are used in fracking, but Encana isn’t using any proppant substitutes for sand. Nor is it adding any new chemicals or increasing the use of any existing additives to make up for the sand.
Balderston said Encana is speculating that the sandstone formations it is targeting in the Piceance are brittle, with natural fractures. Fracking connects those fractures a little better, and they may stay open because they’re already broken, Balderston said. It could be that shards in the formation are liberated during fracking and act as proppants themselves, he said.
“That’s pretty fascinating, and certainly I can see it as being technically feasible,” the School of Mines’ Boak said of Encana’s no-sand approach.
Besides neatly doing away with silica-related health concerns and sand-hauling traffic, not using sand also improves the economics of drilling in sandstone formations when natural gas prices are low, Boak said.
“It’s kind of an exciting development for these types of rocks,” he said.
Indeed, Balderston said the savings from no-sand fracking are one of the things that have helped enable Encana to keep drilling in the Piceance despite low gas prices.
Its applicability to other areas of oil and gas development remains in question.
While it’s only being tried by Encana in the Piceance for now, Balderston said it’s something that could apply in the Pinedale, Wyo., area, where Encana also operates.
But he adds, “It’s a big leap of faith,” noting that it costs $2 million to drill and develop a well, money that is gambled if tried without sand.
“There’s no redos on that,” he said.
Said Seminario, of the AFL-CIO, “The industry is now focused on this (sand) issue and it would be very important to see if (Encana’s) approach is viable in other locations and with other rock formations. If it is, it would eliminate the problem of silica exposure in this industry, which would be a huge step forward with a major health hazard.”
Less-brittle oil and gas formations more characterized by shale, silt and clay are likely to continue to require sand or another proppant to keep cracks opened during fracking from collapsing, Encana believes.
Still, in the Piceance anyway, the advantages for Encana in doing away with sand are many. No longer does it need to provide safety equipment to address the silica dangers. It doesn’t require sand storage containers at a frack site or have to provide room at the site for sand trucks to maneuver. That means those sites can be kept smaller and Encana has more flexibility in where it can locate them, all of which can reduce their environmental impacts.
Sand also impedes the flow of fracking fluid, and not using it has helped Encana be able to pump fluid from frack operations via pipeline to wells as far as five miles away. Such remote fracking operations are helping companies confine trucking, noise and other impacts to the frack sites rather than having them also occur at well pads.
Abrasive sand also wears out blenders and other frack-related equipment, Balderston said. Frack pump pressure-plungers that can cost $100,000 may last for 200 to 500 hours of use when sand is involved, and 2,000 to 2,500 hours without sand.
“There are 10 pumps just on this site,” Balderston said as he gave a recent frack operation tour north of Parachute.
Sand coming back up wells also must be dealt with as a waste product, and the sand also plugs wells, requiring them to be cleaned.
“We really like (no-sand fracking),” Balderston said. “It really reduces a lot of headaches.”
WPX cuts some sand use
Susan Alvillar, a spokeswoman for WPX Energy, the leading gas producer in the Piceance Basin, said WPX is aware of Encana’s well completions program and will watch the results.
“Whenever a company achieves an enhancement in technology, it serves the entire industry,” she said.
She said WPX has reduced its sand use in the initial phase of well completions, but still uses sand. WPX engineers say there are a lot of variables to consider, such as formation pressure, and the benchmark for determining sand use “is still going to be production of the well over the course of time,” Alvillar said.
Meanwhile, she noted that to address safety, fracking company Halliburton a few years ago developed filter socks for vents on sand containers, which greatly reduces dust.
“Also, there is protective gear that workers can use, such as a respirator,” she said.
Theo Colborn is founder of The Endocrine Disruption Exchange, a Paonia-based nonprofit focused in part on silicosis and other health concerns related to oil and gas development. She said Encana’s shift away from sand use is a welcome and rational development.
“It’s common sense. Where you can do it you should do it,” she said of the approach.
But she said she’s also worried about companies using silica as an additive in drilling, not just fracking. Hock said Encana doesn’t use silica during drilling.
While impressed by Encana’s innovation, Smith, of the Western Colorado Congress citizen group, worries about it maybe being made possible by naturally occurring fractures. He said such fractures complicated matters in the case of gas that seeped from a faulty Encana well into West Divide Creek south of Silt in 2004. He’s also concerned about Encana’s increased water use in fracking.
Hock said the natural fractures Encana is tapping are at a small scale, in the target zone surrounding a well. Energy companies say thousands of feet of impermeable rock separate shallow groundwater and surface water from these zones.
Encana’s frack water use varies from well to well, with some using less and some more than in the past. Balderston estimates that Encana’s average Piceance water use has grown by about 20 percent over three years. However, Hock notes that Encana now recycles and reuses almost all the water used in Piceance fracking.