Characterization of Mass/Heat Transfer in Fractured Geothermal Reservoirs by Means of Mathematical Model for Complex Systems

Abstract

A fractional heat transfer equation (fHTE) has been developed in order to characterize thermal responses in a geothermal reservoir on a basis of fractional advection-dispersion equation (fADE). The fHTE takes into account thermal diffusion from main conduit toward the outside and the inside of a reservoir. Numerical simulations of fluid and heat flow in two models were conducted by using TOUGH2: one is a fault model implemented permeability distribution due to a structure of fault zones to reproduce thermal diffusivity into the outside of the reservoir, and the other is MINC treating interactions between matrix and fractures to generate thermal diffusivity into the inside. The results for the fault model showed that the difference of permeability distribution in the surrounding rocks affected the rate at which temperature dropped. The fHTE was in good agreement with simulated temperature profiles, compared with conventional models. The MINC yielded the intermediate responses in between a porous and a fracture medium. Fitted results of fHTE on the MINC results suggested that the fHTE is efficient to characterize thermal response from a fractured medium to a porous medium and would provide a time-saving and more precise approach for characterizing thermal response in a fractured reservoir.