GE Water & Process Technologies and STW Resources, Inc., (STW), a new company formed to use GE technology in water reclamation, formed a collaborative that will use a new, cost-effective process and patented GE thermal evaporation technologies to help oil and gas customers recover up to 70% of their hydraulic fracturing wastewater. Hydraulic fracturing is common technique used to increase the production rate of oil and gas wells, and creates billions of gallons of wastewater annually.
A conventional hydraulic fracture system combines freshwater with proppant (sand) and a polymer system. The polymer portion provides viscosity or thixotropic characteristics to carry the proppant into the reservoir. The fluid is pumped into the oil or gas bearing zone at very high pressure and cracks or fractures the structure, enabling the proppant to penetrate far back into the zone.
Once the fracture is completed, the pressure drops and the zone settles down on the proppant but does not close. The proppant left behind provides a fracture or a path with a very low permeability for the gas and oil to flow to the well bore. Carbon dioxide or nitrogen energized fluids are also utilized for wells with low bottom hole pressure to prevent fluid loss.
For the Barnett Shale region—one of the first targets for the GE-STW collaboration—a different fracture system was developed that requires much more water. The “slick water” fracture system—which uses a friction reducer to enable high rates of water—is the most cost effective system to date in the Barnett Shale and is being expanded into Haynesville, Marcellus, Woodruff, Pieance, and Fayetteville Shales.
Use of fresh water in the system has the additional production benefit of dissolving out water soluble salts that were deposited with the shale. Dissolving these salts provides additional paths for the gas to flow through out of the shale or connections of the natural fractures. The resulting produced water, however, has a high TDS (total dissolved solids) content.
The water used is returned during the production phase of the well as a highly-contaminated water that needs to be disposed of in disposal wells. The drilling and fracing process pollutes the millions of gallons of water used at each drill site with at least 26 chemicals including carcinogens such as benzene. Texas alone—the largest oil and gas producing state in the US—discards more than six billion barrels annually of oilfield wastewater into the state’s 50,000 permitted disposal wells. The wastewater disposed of in the wells is forever lost, placing even more stress on this water-scarce region.
The GE-STW collaborative will initially address the wastewater challenges of Barnett, Fayetteville and Appalachian Shale natural gas drilling plays. Utilizing GE patented evaporator and brine concentrator technologies, the effort will help the regions reclaim approximately 70% of their hydraulic fracturing wastewater. The reclaimed water can be reused in the next well or safely returned back to the environment. The water usage for drilling and fracing the active wells in the Barnett Shale area equates to annual average water usage for at least 185,000 households.
The collaborative will also help oil and gas producers further shrink their environmental footprints by decreasing the amount of equipment and water hauling trucks needed on site.
GE and STW will form project-specific companies, under the banner of “Water Reclamation Partners,” and will offer multi-year cost-per-barrel based service agreements. Water Reclamation Partners will build, own, and operate the equipment and processes required to treat the wastewater and recover reusable water.