Propagation of the Cooled Region in a Small Fractured Geothermal Reservoir

Abstract

A small fractured geothermal reservoir is investigated wherein a doublet is used to supply energy for a pilot power plant. The effect of the injection on the reservoir temperature is a cooled region from the injection well propagating toward the production well. The distance between the wells is the same order of magnitude as lateral extent of the reservoir. In the model the fractured reservoir is replaced by an equivalent fracture. Inside of the closed contour a Hele-Shaw flow occurs. Perpendicularly to the fracture a transient conductive heat flow is developed in the rock mass. The simultaneous problem of the flow and the heat transfer is solved by applying the method of the singularities. The closed contour of the reservoir is obtained as source and a sink is superimposed to a fictitious parallel flow. Applying this method together with a tracer test can be determined the exact size and the lifetime of the reservoir.