Injection into a Fractured Geothermal Reservoir

Abstract

A detailed study is made on the movement of the thermal fronts in the fracture and in the porous medium when 100°C water is injected into at 300°C geothermal reservoir with equally spaced horizontal fractures. Numerical modeling calculations were made for a number of thermal conductivity value, as well as different value of the ratio of fracture and rock medium permeability's. One important result is an indication that although, initially, the thermal front in the fracture moves very fast relative to the front in the porous medium as commonly as expected, its speed rapidly decreases. At some distance from the injection well the thermal front in the fracture and the porous medium coincide., and from that point they advance together. The implication of this result on the effects of fractures on reinjection into geothermal reservoirs is discussed.