Slick water frac is any water used in shales that doesn’t contain high levels of gelling agents and uses friction reducers. This water is composed of 98-99% water (by volume), 1-1.9% proppant (by volume) and the remainder is made of chemicals. These chemicals include:
- Friction reducers, or a form of non-acidic polyacrylamide (.025% by volume). This substance is used in baby diapers for its ability to absorb fluids. It is used during fracking to reduces the horsepower at which pumps have to function, which helps reduce air emissions.
- Disinfectants, also known as biocides, these chemicals make up .05-.005%, by volume, of slick water frac. These biocides help limit the growth of microbes that could lead to the creation of sour gas, or destroy frack fluids. Currently, scientists are working on developing biodegradable biocides. The following biocides are commonly used in fracking and are both found in hospitals, municipal water systems, and over-the-counter skin antiseptics.
- quaternary amine
- Surfactants which prevent and break emulsions, and modify the surface tension.
- Thickeners, or gelation chemicals, are used in hybrid frack fluids and include common food additives such as cellulose polymers and guar gum. These chemicals are not concerning because they do not break down in toxins.
- Scale inhibitors are used in varying amounts depending on the shale formation and include phosphonates, phosphate esters and polymer. All three of these chemicals are similar to detergent and are non-toxic in the amounts used at fracking sites.
- Hydrochloric acid may be used at some sites to reduce pressure when first cracking into the shale rock. This acid is used up within the first few inches of drilling into the rock. No acid returns to the surface and instead the hydrochloric acid is returned into water, some CO2 and calcium chloride. The hydrochloric acid levels seen in frack fluid are slightly higher than those seen in swimming pool water.
- Corrosion inhibitors are one of the few potentially toxic, organic compounds used in fracking. These inhibitors are not always used; their use varies from formation to formation. Most of these inhibitors, 90-90% are absorbed into the steel used during the fracking process.