the case or if it is desired to further increase the fluid conductivity the formation in the injection well production well or both may be subjected to remedial action in order to increase the permeability of the formation one common method for increasing the permeability of the formation which has been practiced for a number of years in the art is known as hydraulic fracturing in this method artificial fractures or channels of high fluid conductivity within the formation can be formed the geothermal reservoir formation in the injection well or the production well employed in this process can be conveniently fractured by methods well known in the art by pumping a fluid down the well bore and into contact with the formation at a rate higher than that at which the fluid can flow into and through the formation on continued injection of the fluid the pressure within the well bore increases to a pressure at which the formation breaks down to create one or more fractures or fissures extending outwardly from the well bore into the formation the hydraulic fracturing fluid is injected into the formation at a sufficient pressure and flow rate to generate the required fracture and to displace the fluid into the fracture under laminar flow conditions any of the commonly employed hydraulic fracturing fluids such as water hydrocarbon oils or oil in water emulsions etc together with viscosity thickeners and other additives may be used in fracturing the geothermal reservoir formations after the pressure on the fracturing fluid has been reduced the fractures will tend to close somewhat because of the unbalanced compressive forces in the formation if desired propping agents may be included in the hydraulic fracturing fluids previously described to prevent closure of the fractures or.