Automatic Calibration of Geothermal Reservoir Models through Parallel Computing on a Workstation Cluster

ITOUGH2 is an optimization code that allows estimation of any input parameter of the nonisothermal, multiphase flow simulator TOUGH2. ITOUGH2 inversions are computationally intensive because the so-called forward problem, i.e., the simulation of fluid and heat flow through the geologic formation, must be solved many times for different parameter combinations to evaluate the misfit criterion or to numerically calculate sensitivity coefficients. Most of these forward runs are independent from each other and can therefore be performed in parallel. Message passing based on the Parallel Virtual Machine (PVM) system has been implemented into ITOUGH2 to enable parallel processing of forward simulations on a heterogeneous network of Unix workstations or networked PCs that run under the Linux operating system. This paper describes the PVM system and its implementation into ITOUGH2. Examples are discussed, demonstrating the use, efficiency, and limitations of ITOUGH2-PVM.