Slickwater or slick water fracturing is a hydro-fracturing method to increase fluid flow by adding chemicals to the water. The chemical additives are engineered to have consistent and predictable properties to control viscosity, friction, formation-compatibility, and fluid-loss control. This engineered slickwater is forced down the well-bore at very fast rates to fracture the shale. The slickwater can be pumped down the well at 100 bbl/min, whereas the top speed of pumping without using slickwater is around 60 bbl/min.
Adding a polyacrylamide is added to water, reducing friction and increases the speed at which the fluid can be pumped into a well to frack shale. 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. Alternatively, bioremediation can be used by introducing hydrocarbon-eating microbes to mitigate contamination. 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 fracking 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, and as a result, hydro-fracturing activity is heavily regulated by state agencies. This is especially true when the wells receiving 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.
The make‐up of fracturing fluid varies from one geologic basin or formation to another.
Evaluating the relative volumes of the components of a fracturing fluid reveals the relatively small volume of additives that are present. The additives depicted on the right side of the pie chart represent less than 0.8% of the total fluid volume. Overall the concentration of additives in most slickwater fracturing fluids is a relatively consistent 0.5% to 2% with water making up 98% to 99.2%.
Because the make‐up of each fracturing fluid varies to meet the specific needs of each area, there is no one‐size‐fits‐all formula for the volumes for each additive. In classifying fracturing fluids and their additives it is important to realize that service companies that provide these additives have developed a number of compounds with similar functional properties to be used for the same purpose in different well environments. The difference between additive formulations may be as small as a change in the concentration of a specific compound.
