The Texas Railroad Commissioners has approved a pilot project that may help conserve fresh water as well as limit the disposal of waste saltwater from drilling operations through a process that recycles drilling waste water on site. The process involves on-site distilling units that apply heat to separate brine from water used to fracture gas formations. In the Barnett Shale — a geologic formation that is underneath an approximate 17-county area centered around Fort Worth — operators are producing previously inaccessible gas by using fresh water to fracture (frac) formations and release gas through these fractures. An average frac job uses about 55,000 barrels of water. When water injected to fracture formations returns to the surface, it is known as frac-flow back fluid but becomes unusable due to its high salt content and must be transported to a disposal well.
Under the pilot program, instead of hauling unusable frac fluid to a disposal well, the frac-flow back fluid will be stored in tanks on location and piped into treating equipment. Natural gas produced on location will boil the used frac fluid and produce fresh distilled water. Is it estimated that 85 percent of the used frac fluids will be converted to fresh distilled water. It is estimated that for every 2,350 barrels of frac fluid, 2,000 barrels of distilled water and about 350 barrels of concentrated salt water and dirt will be recovered. The distilled water will then be used to frac another well. The concentrated salt water and dirt will be removed by a permitted RRC hauler to a permitted saltwater disposal well.
RRC Chairman Victor Carrillo said, “This technology holds the promise of addressing two issues in the rapidly developing Barnett Shale area – the use of fresh water to fracture gas formations and the disposal of this waste water after a formation is fractured. If this technology works the way we believe it will, it will offer tremendous benefits by allowing up to 85 percent less fresh water to be used at each frac job. This process also would help reduce the amount of wastewater that must be disposed into injection wells.”