The vaporisation of liquid injected into a fracture bounded by impermeable superheated rock

Abstract

We describe a theoretical model of the fluid flow, heat transfer and phase change which occurs when liquid is injected into a fracture bounded by a hot, impermeable rock. We first consider the case of a warm host rock, in which there is no boiling of the water. We then develop the model to describe the case in which the host rock temperature is in excess of the boiling temperature and the water boils. We show that a two-phase boiling zone develops between purely liquid and purely vapour filled regions in the fracture. The results are compared successfully with new laboratory exper-
iments in which both water and ether spread radially from a central source into a fracture consisting of two hot glass plates. The work has direct implications for understanding vapour regeneration as a result of liquid injection and boiling in a geothermal reservoir.