Hydraulic fracturing has sparked debate and controversy because of the potential environmental and social consequences. Yet, the majority of evidence for the hazards is anecdotal, and much remains unclear about the long-term effects.
Fremont, CA: When the pressure laid on the fluid contained within a rock surpasses a particular threshold, hydraulic fracturing occurs. This can happen naturally or be induced purposefully. Until recently, hydrocarbon production was limited to natural reservoirs, and the hydraulic fracturing necessary for this process posed no environmental risks. However, this method has been used to extract hydrocarbons from their mother rock for the past fifteen years or more. To avoid any negative environmental impact, this application now demands improved control of the geometry of hydraulic cracks.
Some of the problems related to hydraulic fracturing are:
Hydraulic fracturing as a tool for hydrocarbon extraction
Hydrocarbons are formed when organic matter decomposes on the ocean floor, among the other components that will eventually create sedimentary rocks. Hydrocarbons tend to travel to the most porous portions of sandstone and limestone when these sedimentary materials are buried deep down. As a result, a separation occurs between mother rocks, which create hydrocarbons, and reservoir rocks, which store hydrocarbons over geological time periods. There is a possibility of pollution of the groundwater table used for current consumption if operations are too shallow. The essential solution to the issue is to have technologies that can manage the vertical extension of hydraulic fractures in real-time in order to reduce pollution threats.
The phenomenon of hydraulic fracturing
A hydraulic fracture is a pure tensile failure that occurs in a plane whose orientation is determined by stress. The rate at which a hydraulic fracture propagates is determined by the distribution of fluid pressure within the fracture. The propagation process is stable when the fracturing fluid is an incompressible liquid, since as soon as the rupture begins, the volume of the crack rises, causing the pressure in the fluid to drop. The liquid must be injected into the fracture to propagate it, hence the rate of propagation is determined by the injection rate. When the injection is finished, the fracture is finished as well. Controlling the geometry of artificial hydraulic fractures thus necessitates an understanding of the massif's minimum primary stress fluctuations.
