Hydraulic fracturing is a process used to extract natural gas from unconventional reservoirs such as tight sands, coal beds and shale formations. It is done by pumping the fracturing liquid into the wellbore at high pressure at a depth of interest so that the pressure exceeds the tensile stress of the rock and causes the rock to crack. Creating fracture is desirable because it allows a conductive pathway in low permeable rocks to be created. This allows hydrocarbons to be extracted easier. Fracturing liquid used involves a base fluid, additives and proppant. In some cases, compressed gas can be used with fracturing fluid such as CO2 or N2 to use less water, but it also reduces the proppant that will be deposited in the fracture. The disadvantage of using hydraulic fracturing includes high water usage, possible aquifer contamination and increased surface footprint.
The fracturing method in interest is slickwater fracturing. The fracturing fluid contains more than 98% of water and sand. Additional chemicals may be added to the fracturing fluid to reduce friction, corrosion and bacterial growth. By using liquid with low viscosity, the fracture that is created has less width and higher fracture length. This increases the complexity of the fracture network and it is good for reservoir-to-wellbore connectivity. The disadvantage of this method includes poor proppant transport, high pump rate require preventing proppants from settling, excessive water usage and narrower fracture widths. Hydraulic fracturing allows accurate prediction of fracture dimensions based on previously studied in situ stress, reservoir properties and fracturing fluid properties.