How fracking fluid is used with shale gas
Photo by Daniel Foster
Fracking fluid is used as injection and fracture rocks allowing the recovery of shale gas from areas where otherwise it could not be recovered. There is much debate as to whether the backflow from fracking fluid affects groundwater and endangers the health of area residents. For instance, some of the drillers working on the Marcellus Shale in Pennsylvania had to move their backflow to Ohio for it to be disposed of.
There are many chemicals included in fracking fluid, even though by far most of the mixture is water and sand. In earthquake prone areas, the pressure at which fracking fluids are injected may be lower, to alleviate some of the chance for earth tremors. Using less fluid and placing it under less pressure, along with recycling wastewater by reusing it are also steps taken to avoid pollution of groundwater and the possibility of creating tremors.
Hydraulic-fracturing stimulates the recovery of gas in shale formations, but it takes a tremendous amount of fluid to allow fracturing to occur. The fluid used is actually a proprietary mixture for each company, but they all consist of about 98% sand and water, with only 2% or so being made up of chemical additives.
The chemical makeup and composition of fracking fluid
There are possible chemicals used that number in the hundreds, but usually each well uses about 12 different chemicals when fracturing is employed. Many of the chemical additives are common, but some have hazardous classifications. After injection, between 20 and 40 percent of the original fluid flows back up to the ground surface, and then it must be disposed of. Four commonly used options for disposal include storage in open air pits, underground injection, treatment and then discharge or recycling the fluid for additional fracking operation.
The backflow of fracking fluids is often disposed of by injection in well sites with large underground areas that are sealed by impermeable rock layers. Disposal wells are operated by many energy companies, and there have not been many incidents caused by chemical migration to – or contact with – aquifers.
Fracking fluid may have harmful effects to the Earth and to people, and this is important to be addressed. There are very few cases of people who have been harmed from contact with any fracking fluids or their flowback. Selecting the proper sites and cementing casings in wells will lessen the chance of groundwater contamination, as will the proper management of injecting, hauling and disposing of these fluids. The most serious of chemical irritants in the fluid is always designed to be kept from contaminating groundwater.