Slickwater or slick water fracturing is a method or system of hydro-fracturing which involves adding chemicals to water to increase the fluid flow. Fluid can be pumped down the well-bore as fast as 100 bbl/min. to fracture the shale. Without using slickwater the top speed of pumping is around 60 bbl/min.
The process reportedly involves injecting friction reducers, usually a a polyacrylamide. Biocides, surfactants and scale inhibitors can also be in the fluid. Friction reducers speed the mixture. Biocides such as bromine prevent organisms from clogging the fissures and sliming things up downhole. Surfactants keep the sand suspended. Methanol and naphthalene can be used for biocides. Hydrochloric acid and ethylene glycol may be utilized as scale inhibitors. Butanol and ethylene glycol monobutyl ether (2-BE) are used in surfactants. Slickwater typically uses more water than earlier fracturing methods--between one and five million gallons per fracing operation.
Other chemical compounds sometimes used include benzene, chromium and a host of others. Many of these are known to be toxic and have raised widespread concern about potential water contamination. This is especially true when the wells recieving slickwater hydro-fracturing are located near aquifers that are being tapped into for local drinking water. However, reports of actual drinking water contamination appear either very scarce or else non-existent. Hydro-fracturing activity is heavily regulated by state agencies.
In summary, slickwater is a water-based fluid and proppant combination that has low-viscosity. Slickwater fracturing was first used in the Barnett shale. Mitchell Energy introduced the very first slickwater frac that utilized 800,000 gal. of water and 200,000 lbs. of sand as proppant. It is typically used in highly-pressurized, deeper shales, while fracturing fluids using nitrogen foam are more common in more shallow shales and those that have lower reservoir pressure.