Hydraulic fracturing (hydrofracing) is the key that unlocks gas shale plays -- the bedrock of the industry's supply renaissance. While growing environmental concern over the well stimulation technique has sent shivers through the gas patch, a researcher at Houston's Rice University and a small start-up company think they have something that could all but eliminate the worries while simplifying the process and cutting producer costs.
Environmentalists, state and federal lawmakers and others are focused on the chemicals in hydrofracing fluids and whether they can poison water supplies. Their concern could spawn potentially industry-crippling rules on hydrofracing (see related story; NGI, Oct. 26; Sept. 28).
But Rice's Andrew R. Barron, a professor of materials science, told NGI the focus on hydrofracing fluids is misplaced. It is the proppant that the fluids are designed to carry into the fractured rock that holds the key to the solution.
Chemicals are used to control the hydrofracing fluid's viscosity. Hydrofracing fluids need to be viscous in order to carry proppant into the fractures that are opened in gas-bearing formations during the hydrofracing process. It's the proppant -- sometimes sand but often small particles of ceramics or other material -- that keeps the fractures from collapsing after they've been opened.
But if the proppant is significantly lighter, a less viscous fluid can be used to carry it. Barron, the university's Charles W. Duncan Jr. -- Welch chair of chemistry, has developed a proppant that is about half the weight of what is typically used in shale plays. Barron's proppant is more buoyant, meaning a less viscous hydrofracing fluid -- even water -- can carry it a greater distance into fractured formations.
From an environmental standpoint, the most obvious benefit of the lighter proppant is that hydrofracing fluids could become less hazardous, even benign, and most important, hydrofracing operations could use less water. In the field, lighter proppant means less costly fluids that are easier to handle. Hydrofracing could also be done at lower pressures, which would reduce wear and tear on pumping equipment as well as allow for more accurate control of the fractures, Barron said. Lower pressures also would mean a reduced risk of contacting water wells during hydrofracing -- something producers fear as much as nearby landowners as they want to produce gas, not water from neighboring wells.
"In addition, the amount of fluid you have to use is potentially a lot less," Barron said. "You're not using as much water. You're not using all the chemical additives, or maybe using very small amounts of them for other control issues...and I think that's a critical component.
"My feeling is that the government seems to be intent on instead of solving a perceived problem by looking at the whole technology, they're just saying, 'oh, this is bad.'"
The lighter proppant would benefit the industry as well. Barron said a Barnett Shale well fractured with conventional proppant (with a specific gravity of 4, for instance) yields 20-30% recovery of the gas in place. Using a proppant with a specific gravity of about 2 with the appropriate fluid could allow for recovery of as much as 60% of gas in place. "It's because you get [the proppant] far deeper into the fracture and also this control issue...that allows you to access more of the material," he said.
"If you can go that much deeper into the fracture, that's that many fewer wells you drill...As an environmental impact, if you drill on a certain acreage 10 wells instead of 100, your environmental impact is quite significantly reduced, and you're getting the same amount of gas.
"Your gain is one, you're not using the chemicals; two, you're getting a larger volume of propping of the fracture than you would using a dense [proppant] material. The only way you could get that same volume with a dense [proppant] material is if you used a very viscous fluid and extremely high pressures, so your potential damage to the gas-bearing rock formation is much higher."
Barron, who was sponsored by oilfield services giant Halliburton to do research on guar gum -- a common frac fluid ingredient that has its widest use in the food industry -- also has done research funded by the U.S. Environmental Protection Agency (EPA). The EPA was interested in green processes in the area of ceramics. Part of what Barron and his colleagues learned was how to make hollow ceramic spheres that are strong and almost perfectly round, making them ideal for use as a proppant. "The technology that was involved in this green ceramic processing was spun off from Rice to a start-up company called Oxane Materials [Inc.]," he said.
Hence, Oxane, which was incorporated in late 2002, was a company with a solution that was looking for a problem when it turned its attention to the needs of the energy industry.
"For the last five years the company has been overwhelmingly focused on developing game-changing proppants that attack 'Holy Grail' problems," explained Oxane President Chris Coker. "For the last 30 years the industry has been trying to develop a high-strength, lightweight proppant and failing. We feel we really are the first to do so."
However, Coker allows that many of the incumbent proppant manufacturers are at work in the same area. Oxane expects to have its manufacturing plant online in March. The company has funding from private equity groups, wealthy families and industry partners and currently employs 22 with expectations of growing the payroll to more than 60 by April, Coker said.
"We certainly hope to experience very strong adoption, much as horizontal drilling has experienced very strong adoption in unconventional gas plays," Coker said. "I believe that as we go from a conventional [gas] world -- hard to find but easy to produce -- to an unconventional world -- easy to find but very hard to produce -- the importance of technologies that unlock the rock and guide you to the point in the rock that is the best to produce, that those technologies will experience very rapid adoption."
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