Fresh water injection into a geothermal reservoir which contains superheated vapor and solid phase salt

Abstract

A mathematical model is proposed for the process with two unknown phase transition interfaces. At the leading interface, evaporation occurs and a salt precipitates. The interface that moves at a lower velocity is a dissolution surface. In the isothermal approximation the self-similar solution is obtained. It is shown that fresh water injection may lead to solid precipitate transfer from one region to another, substantially increasing the precipitate content behind the evaporation front. This significantly decreases permeability and, hence, the flow velocity through permeable rocks. With approaching the critical parameter region the branches of the obtained two-valued self-similar solution also approach and at critical values merge, which corresponds to the disappearance of the solution. The non-existence of the self-similar solution can be interpreted as the filling of the pores with salt precipitate and the flow arrest in the geothermal reservoir.