GEOTHER, 2-D Heat Transport and 2-Phase Fluid Flow in Porous Rock

1 - Description of program or function: GEOTHER is a three-dimensional, geothermal reservoir simulation code. The model describes heat transport and flow of a single component, two-phase fluid in porous media. 2 - Method of solution: It is based on the continuity equations for steam and water, which are reduced to two nonlinear partial differential equations in which the dependent variables are fluid pressure and enthalpy. These equations, describing three-dimensional effects, are approximated using finite-difference methods and are solved using an iterative technique. The nonlinear coefficients are calculated using Newton- Raphson iteration, and an option is provided for using either upstream or midpoint weighting on the mobility terms