Drilling fluids (water combined with additives) are used during the drilling process to transport drill cuttings to the surface, stabilize the formation around the wellbore, and clean, cool and lubricate the drill bit.
Water is the main component of fracturing fluid; it is pumped into the well at high pressure to fracture the rock. Fracturing fluid is comprised of approximately 99.5% water and proppant (sand or ceramic pellets), and 0.5% chemical additives.
After being injected into the well, a portion of the fracturing fluid will be produced back (returned) to the surface. The amount of fluid that returns to the surface depends on the local geological characteristics. The rest of the water remains in the formation and may be slowly produced over a long period of time.
Recycling and disposal
Any water captured during the drilling and hydraulic fracturing process is either recycled or disposed of according to government guidelines and regulations.
In some instances, returned water is sent to industrial waste facilities which process the water for safe disposal. Returned water can also be recycled or safely re-injected into abandoned reservoirs. Where suitable geology and sealed geological formations exist, water is typically injected into a non-potable saltwater aquifer, which are thousands of meters below the earth’s surface.