Numerical modelling of brittle–ductile transition with the MUFITS simulator

The numerical modelling of flows in geologic porous media, accounting for plastic behaviour of rocks at high temperatures and hydrofracturing at high fluid pressures, is required for a better understanding of hydrothermal and volcanic systems. The investigation of these systems is limited given the lack of reliable and available reservoir simulation software that accounts for complicated rock behaviour at elevated temperatures. In this paper, we present such software as an extension of the MUFITS reservoir simulator. We describe the mathematical model utilised for modelling the permeability changes of elastic and plastic rocks and input data formats to the simulator. We present several application examples related to the modelling of brittle–ductile transition in hydrothermal systems, in particular perturbed with the emplaced degassing magma body, and provide the corresponding simulator input data to facilitate and ease its further usage.