Modelling ground displacement and gravity changes with the MUFITS simulator

Abstract

We present an extension of the MUFITS reservoir simulator for modelling the ground displacement and gravity changes associated with subsurface flows in geologic porous media. Two different methods are implemented for modelling the ground displacement. The first approach is simple and fast and is based on an analytical solution for the extension source in a semi-infinite elastic medium. Its application is limited to homogeneous reservoirs with a flat Earth surface. The second, more comprehensive method involves a one-way coupling of MUFITS with geomechanical code presented for the first time in this paper. We validate the accuracy of the development by considering a benchmark study of hydrothermal activity at Campi Flegrei (Italy). We investigate the limitations of the first approach by considering domains for the geomechanical problem that are larger than those for the fluid flow. Furthermore, we present the results of more complicated simulations in a heterogeneous subsurface when the assumptions of the first approach are violated. We supplement the study with the executable of the simulator for further use by the scientific community.