Heat Extraction Simulation from Fractured Rock by a Double Porosity and Double Permeability Model

Abstract

LINC (Line-Source (Sink) Implanted Networks for Fractured Continua) method based on a double porosity and double permeability model is proposed in order to analyze the heat and fluid flows in fractured rock formation. In the present method the heat and fluid flows in the fracture and those in the less permeable rock are calculated separately, then the interaction between the fractures and the rock formation is taken into account through sink and source terms in the governing equations, describing the transport phenomena in the respective system. A specific problem to which the present numerical method is applied assumes a single fracture that drains heat from neighboring blocks of homogeneous and isotropic imkpermeable rock. The outlet temperature history is monitored to evaluate the amount of heat extraction from the rock. The numerical results by the present method are favorably compared with the available analytical data. And it is observed that the outlet temperatures at early times of heat extraction measurably decrease if the fluid properties are considered to change with thermodynamic condition.