During its first nine months of operation, Devon’s water reuse project in the Cana-Woodford shale play saved nearly 5 million barrels of water.
The timing could not have been more beneficial. During the summer of 2012, Oklahoma’s drought approached historic proportions. At one point, 90 percent of the state was categorized as being under an extreme or exceptional drought.
Success of the water-reuse project allowed Cana well completions to continue as planned, in spite of the drought. More than 3 million barrels (126 million gallons) of water are expected to be reused by the end of 2012, said Jim Heinze, production engineering manager.
The idea to reuse water in the play dates back to 2008, shortly after Devon drilled its first Cana wells. Company officials realized the play’s flow-back water was of sufficient quality to be used again without extensive filtration.
Devon built the water recycling facility after working with the Oklahoma Corporation Commission to establish new rules to build a large reservoir. The project includes a 500,000-barrel storage reservoir and a series of pipelines that connect well sites to the recycling facility.
"This dramatically reduces our need to pull water from farm ponds or the North Canadian River for future development," Heinze said.
Another public benefit: Reduction of truck traffic. During the first three months alone, transporting re-usable water via pipeline eliminated the need to dispose of an estimated 7,400 truckloads of wastewater, Heinze said.
The project also reduces Devon’s water disposal costs. Recycling the water costs far less than trucking it to a disposal well.
Water quality proves serendipitous
The project is possible largely because of the composition of the water in the Cana-Woodford. Water there that flows back to the surface after hydraulic fracturing contains, on average, about 20,000 parts per million of salts. This relatively low level allows Devon to reuse the water once the solids are removed. By comparison, seawater is nearly twice as salty: roughly 35,000 to 40,000 parts per million.
We aren’t always so fortunate. In the Barnett Shale, for example, flow-back water reaches 60,000 parts per million of salts. This high concentration requires us to distill the water before reusing it.