Slick water hydrofracking
Slick water hydraulic fracturing is also known as hydrofracking. Slick water hydrofracking uses significantly more water than standard usual drilling, as well as a “slick water” mixture that is pumped into the shale to fracture the rock and release the gas.
What is a slick water frac?
Slick water frac is a kind of frack fluid—a combination of water, chemicals, and sand that is injected into a natural gas well or crude oil well to reduce friction pressure and create a fracture. During hydraulic fracturing (also known as fracking), fluid is injected at a high speed into a wellbore to increase the release of natural gas or oil located under the earth.
Geological features near the area being fractured determine the chemical composition of slick water frac fluid. Usually, the frack fluid contains between 98 percent and 99.5 percent water and sand. To stop the growth of microorganisms, between 0.5 percent and 2 percent of the fluid is composed of chemical additives, which can also prevent well-casing corrosion and increase the rate at which the fluid is injected. Pressure can also be reduced, among other things. Sand and chemicals are transported in part by the water that is being used from the wellhead to the bottom of the well to increase the well’s production of gas and oil.
Friction reducer and other chemicals used in slick water
An additive that is commonly used in slick water frac fluid is a friction reducer. This additive lowers the friction pressure to moderate pumping pressures to a more controllable level. Disinfectant chemicals are used in slick water frac fluid include limiting the growth of microbes that can break down frack fluids. In order to lower surface tension in slick water, frack surfactants can also be used. Scale inhibitors are used in varying amounts depending on the shale formation to prevent a build-up of minerals in the inner wall or casing of a well just as corrosion inhibitors can be used to protect casing and equipment from corroding. At some sites, in order to reduce pressure when shale rock is first cracked, hydrochloric acid is used in the earlier stages of drilling.
Hydraulic fracturing fluid
Hydraulic fracturing or fracking is a method of oil and natural gas extraction. Fluid is injected into subterranean rock formations at high pressure and this high-pressure fluid produces a fracture that allows crude oil and natural gas to flow into a wellbore to be extracted at the surface. The fluid contains between 98 percent and 99.5 percent water and sand and between 0.5 percent and 2 percent of the fluid is composed of chemical additives. Fracturing fluids are divided into seven categories: water-based fluids, oil-based fluids, acid-based fluids, alcohol-based fluids, energized fluids, foams, and emulsions.
Hydraulic fracturing fluid viscosity
Hydraulic fracturing fluid should have a stable viscosity during pumping oil and gas. Following the pumping, it needs to be broken to reduce the viscosity, essentially water, at the end of the fracturing treatment, so as to allow the clean up of fluid from the formation prior to production.
Hydraulic fracturing crosslinked fluid
There are several types of hydraulic fracturing practices. Three classes of fluids seem more capable to optimize what is needed.
Foamed fracturing fluids generally are composed of 75-80 percent gaseous nitrogen and 20-25 percent water. This is generally clean, has good proppant suspension and carrying capabilities, and provides relatively easy cleanup of formation and fractures. It may not be feasible to use foam because of trying to get the desired maximum proppant concentrations before being mixed with the gas.
Viscoelastic surfactant fluids have a gelatin-like consistency and are matchless particle suspension medium. This type of surfactant fluid is composed of ammonium or potassium (salt) and an organic stabilizing additive. The viscoelastic fluid can be broken by contact with formation water or oil. It can cause problems by causing an oily film formation on rocks and is restricted to temperatures below about 110 degrees C.
Crosslinked fracturing gels can carry higher concentrations of proppants due to inherent high efficiency and very high viscosity yields. Crosslinked fracturing gel is composed of aqueous liquid and a crosslinking compound. Because of the high viscosity, crosslinked fracturing gels work well even without a lubricating layer between the fracturing liquid and the well tubing.
