Modelling of heat transfer in fractured geothermal reservoirs

In this work, novel analytical solution to models of heat transport during reinjection of heat depleted geothermal waters into geothermal reservoirs and/or during cold water injection into hot dry rock have been presented. A geological model of infinite number of distinct parallel fractures located in an impermeable matrix have been selected and for the geological model two different heat transport models have been considered. For the first transport model, a purely convective transport within the fracture and perpendicular conduction into the adjacent finite size matrix blocks on two sides of the fracture mechanisms are assumed. For this transport model, a novel model has been developed which is suprior to the previously developed Skopp and Warrick (1975) solution presented for solute transport. In the second transport model in addition to the purely convective transport within the fracture and perpendicular conduction into the adjacent finite size matrix blocks on two sides of the fracture, a hydraulic dispersion along the flow direction mechanisms is assumed. Until today only Laplace Space solutions (semi-analitical solutions ) of this model have been presented and numerical Laplace Invertion algorithms have been employed to compute return profiles. In this work, a novel closed form analytical solution (real space) has been developed by using iterated Laplace transform method. Finally, nonlinear regression analysis of these two transport models have been performed to match model results with experimental data and to estimate model parameter values.