Water Use in the Barnett Shale

While the positive economic impact of the Barnett Shale on North Texas is becoming clear--thousands of new jobs and billions of dollars injected into the economy, insulating North Texas from the national economic downturn--there are also many questions.

One is the use of water for drilling in the Barnett Shale.

Know this:  Best practices in the energy industry promote the economical use of fresh water -– not only because it is a precious natural resource, but also because it is costly. There is no question that gas drilling does requires what appears to be significant amounts of water.  However, the Tarrant Regional Water District has reported that use of water by the natural gas drilling industry has been running less than 2% of total water used in the region.

The Barnett Shale formation is so dense and impermeable that hydraulic fracturing (or “fracing”) is the only economic means of developing the reserves.  Hydraulic fracing means pumping large amounts of fresh water into a well with enough pressure to create artificial fractures in the dense rock, thereby liberating the natural gas trapped inside.

You may wonder: why use fresh water for this purpose? Why not re-use water, or use the saline water that is so abundant deep underground?   The reason is because saltwater corrodes wells and drilling equipment and it isn’t compatible with the additives that are used in the drilling and fracturing operations.  It is also less environmentally friendly when storing and handling on the surface.

The energy industry and Texas A&M researchers are studying techniques for recycling wastewater for use in frac operations as well as other applications. There are two stages to recycling wastewater: the first and easiest stage is to filter out shale cuttings and other suspended materials. The second, more difficult stage, where research and development are underway, involves getting rid of dissolved materials in the water, such as salt and leftover chemicals, through a distillation or membrane treatment.

According to David Burnett, a professor at Texas A&M’s Global Petroleum Research Institute, industry has an incentive to recycle more water used because of the expense and impact of hauling it to off-site disposal locations. 

Devon Energy Corporation is a forerunner in this area, and is using distillation technology to recycle water produced at several drilling sites in its Barnett operations.  Each of its four recycling sites treats 200,000  gallons of water per day.  The typical gas well operated by any company can require between 3 million to 4 million gallons of water for fracturing operations, so recycling technology currently makes a modest dent in the overall amount of freshwater being used.

According to Professor Burnett at Texas A&M, in the very near future it will be possible for companies to recycle about a third of the water used in natural gas operations. In another two or three years, he believes, about 50 percent of the wastewater will be recyclable due to advances in the technology. But even then, he says, we will be left with the challenge of getting rid of roughly half of the hyper-saline wastewater. 

In the meantime, the typical method for getting rid of wastewater is to pump it back into the earth from which it came by using high-pressure injection wells. Currently the city of Fort Worth is studying whether to lift its moratorium on such injection wells, but in rural areas within the Barnett Shale, saltwater injection wells are the most common method for disposing of production water.

According to Burnett, the environmental risks of such saltwater injection wells are “more perceived, than real.” The Railroad Commission of Texas and energy companies are designing such disposal wells to be dug so deep that they are far beneath the fresh groundwater supplies used by the public for drinking and other uses. 

“Disposal well operations are inherently safe” when they are monitored and operated according to permit, Burnett says.  A very small risk exists where there may be an old, improperly abandoned well deep underground and no public record to reveal its location. In these very rare instances it is possible for wastewater to leak into the fresh groundwater supply until the situation is quickly discovered and corrected.

“Industry is aware of the adverse impact and is working to cut down on it, but it’s going to take a while,” he says. 

The best solution is for localities to centralize their injection well disposal operations in industrial areas so that the operations can run 24 hours a day with minimum disruption to nearby communities.

Ed Ireland, Ph.D. is executive director of the Barnett Shale Energy Education Council, a consortium of 11 of the leading energy companies operating in the Barnett Shale that are dedicated to promoting energy education and best practices as it relates to oil and gas leasing, drilling, production, transportation and marketing in the Barnett Shale.