What is slick water fracking fluid
Slick water fracking fluid is a combination of water, chemicals, and sand that is inserted into a crude oil or natural gas well to reduce friction pressure and create a fracture. The main functions of these fluids are to open or spread the fractures and transport proppants into the fractures. This technique stimulates hydrocarbon production by generating a network of highly conductive fractures in the area surrounding a wellbore.
Process
Slick water fracking fluid can be used in horizontal as well as vertical wells. Proppants are generally applied under high pressure to form a thin layer between fracture faces to prop the fractures open at the end of the fracturing process. Chemical breakers can then be used to break the polymers at the end of the fracturing process so as to provide highly conductive fractures.
Slick water hydraulic fracturing
Because of concerns over damage in formations another type of hydraulic fracturing fluid was developed. “Slickwater” fracturing fluid consists mostly of water with a very low concentration of linear polymer. The low concentration polymer serves primarily as a friction reducer to lessen the friction loss across the flow lines when pumping the hydraulic fluids downhole.
Three main components in slickwater
Slickwater frac fluid, on average, contains between 98 percent and 99.5 percent water and sand. The chemical composition can vary depending on the geological features near the area being fractured. The chemical additives, which are used to prevent well-casing corrosion and stop the growth of microorganisms, are between 0.5 percent and 2 percent of the fluid. This helps increase the rate at which the fluid is injected and helps reduce pressure. The well’s production of oil and gas is increased due to the water which is used to transport the chemicals and sand from the wellhead into the reservoir. The chemicals added are preferred over the use of oxidizers because enzymes are polymer specific, easy to handle, environment friendly, and homogeneous with the fracturing fluid. Other additives such as potassium chloride, acid, friction reducer, corrosion inhibitors, surfactant, scale inhibitor, pH adjusting agent, biocides, and iron control agents can also be added to fracturing fluid at low concentrations to fulfill different purposes for different fracturing jobs.
Hydraulic fracturing fluid
The three main functions of a fracturing fluid during hydraulic fracturing are the transfer of energy from the frac pumps to the formation, creating the fracture and the transport and suspending the proppant. Since the goal of hydraulic fracturing is to increase the production of hydrocarbons, a fracturing fluid must be compatible with the formation minerals, minimize surrounding formation damage, increase fracture conductivity, and be easily recovered after hydraulic fracturing. The composition of fracturing fluid differs from one geologic basin or formation to another. In general, the concentration of additives in most slickwater fracturing fluids is a relatively consistent 0.5 percent to 2 percent with water making up 98 percent to 99.5 percent. A fracture treatment, typically, will use a very low concentration of between 3 and 12 additive chemicals based on the characteristics of the water and shale formation being fractured. Each element serves a specific purpose. Hydraulic fracturing fluids vary from environment to environment and are designed to meet the needs of each area. In addition to friction reducers, other additives include biocides to prevent microorganism growth and reduce biofouling of the fractures; oxygen scavengers and other stabilizers to prevent corrosion of metal pipes; and acids that are used to remove drilling mud damage. Most of the water and additives used in fracturing remain deep underground where the oil and/or gas is being extracted.
Hydraulic fracturing fluid viscosity
Ideal fracturing fluid should have compatibility with the formation to minimize formation damage and have sufficient viscosity to create a fracture and transport the proppant into the production zone. It should also have a rapid viscosity breakdown after the proppant is placed to maximize fracture conductivity. Hydraulic fracturing fluid viscosity provides sufficient fracture width to ensure proppant entrance into the fracture, generating a desired net pressure to control height growth and provide fluid loss control. The fluid should generate the desired viscosity, to be safe to handle, be environmentally friendly, easy to mix, non-damaging to the fracture conductivity, and inexpensive.
