A perturbation analysis is made for the study of the effect of dike intrusion on free convection in unconfined conduction-dominated geothermal reservoirs. The perturbation equations are of elliptic type that can be solved numerically by the finite difference method. Up to the second-order approximations are retained in the numerical computation. The effects of dike intrusion on streamlines, temperature distribution, and the shape of water table in a two-dimensional volcanic island aquifer are shown.

The problem of steady state free convection in an unconfined aquifer bounded by ocean on the sides with geothermal heating from below is investigated in this paper. The governing nonlinear partial differential equations with nonlinear boundary conditions are approximated by a set of linear subproblems on the basis of perturbation method. The equations for the zero- and first-order approximations are of the elliptic type that can be solved numerically by the finite difference method. Numerical results, accurate to the first-order approximations, are obtained for temperature, pressure, and stream function as well as for the shape of the water table. The influence of the location and the size of the heat source as well as various parameters on heat transfer and fluid flow characteristics in a rectangular geothermal aquifer is discussed.

This paper describes the numerical modelling effort currently being carried out in the Hawaii Geothermal Project. The problems of convective heat transfer occurring in confined and unconfined geothermal island reservoirs are discussed. The effects of geothermal heating and the withdrawal of fluids on heat transfer and fluid flow characteristics are shown.