The use of membrane filtration to recycle water from fracturing flowback is among the research projects being funded by the Research Partnership to Secure Energy for America (RPSEA), a nonprofit organization that works with government, universities, research organizations, and industry.
RPSEA, a program financed by revenues from oil and gas leases to the federal government, is cofunding the Environmentally Friendly Drilling Systems Program (EFD) for 3 years. Previously, EFD was cofunded by the US Department of Energy and industry.
Current EFD funding is part of RPSEA’s efforts that leverage industry spending to develop technology for unconventional gas, specifically to help industry produce shale gas while protecting the environment. The EFD program includes hydraulic fracturing research and other projects.
Richard Haut, senior research scientist at the Houston Advanced Research Center (HARC), currently manages EFD. During 2005-08, EFD was managed by David Burnett, director of Technology for the Global Petroleum Research Institute (GPRI) at Texas A&M.
Both HARC and GPRI are active participants in EFD. Haut said, “Our program takes a systematic approach to develop and integrate new, low-impact technologies that reduce the footprint of drilling and production activities.”
Treating frac water
Burnett’s goal is to treat and recycle frac water to reduce the expense of transporting waste water and also to provide water for more fracturing. He has worked for 10 years on using membrane filters to treat frac water.
Frac water is a mixture of chemical additives and sand to prop open fractures. About 75% of injected frac water is recovered. The flowback water contains traces of barium, calcium bicarbonate, iron, magnesium sulfate, sodium chloride, and strontium that it picked up while passing through the rock formation.
A petroleum engineer, Burnett has discovered that more than 12,000 different types of membranes exist but only 15-50 types are available in commercial quantities. He works to find membranes that are suitable for oil and gas operations.
Researchers at the Global Petroleum Research Institute at Texas A&M University built a mobile pretreatment and desalination unit to extract fresh water in the treatment and recycling of water used in hydraulic fracturing. Photo from David Burnett of Texas A&M.
“Instead of trying to invent a new membrane, I am trying to find a membrane that already has been invented and seeing if it is useful,” Burnett said. “I am a bridge between the scientist in the laboratory and the guy that wants to do something in the field.”
He built mobile treatment units for demonstration purposes using membranes that were designed originally for seawater desalination. About half the flowback water can be recycled, and the rest must be reinjected into saltwater disposal wells, he said.
“We know the technology works. We need to show that the technology works for long periods of time, like 1-2 years, and make sure it’s cost effective.”
Treatment costs
The operating cost of actually doing the treatment is less than $1/bbl, Burnett said. Other costs involve transporting the water and disposing of the waste removed from the flowback water.
“Based on what I know, I would estimate that less than 10% of the potential Barnett shale water is being treated right now,” Burnett said. He believes the Fayetteville shale play could benefit from the membrane filters based upon the Fayetteville shale’s salinity. Membranes are apt to prove very beneficial in the Haynesville shale, he said.
“The Marcellus shale is the biggest problem because the water is hypersaline, and so it needs a pretty robust pretreatment before you can deploy a membrane,” he said.
The fracturing flowback salt content of Barnett shale averages 100,000 ppm while that of Marcellus is more than 200,000 ppm. The salinity of seawater is 33,000 ppm.
Membrane filters also could prove helpful in the Bakken oil shale because the technology to complete those wells is the same as gas shale, Burnett said.
Recently, Texas A&M licensed its membrane filtration technology to M-I SWACO, which plans to put a pilot filtration unit in either the Barnett or the Marcellus shale this year.
