Computational study of two-phase flashing flow in a calcite scaled geothermal wellbore

This work presents a computational study to understand different heat transfer and phase transition processes of two-phase flow in a geothermal wellbore. The simulation uses a six-equation model with mass, momentum, and energy balance equations for the liquid and vapour phase, which is available in Ansys Fluent. The model considers the effect of phase transition due to flashing, caused by thermal non-equilibrium at the liquid-vapour interface. Two wellbore scenarios, one with a constant inner diameter and the other a variable inner diameter along the flow direction due to calcite scaling, were simulated using the model. Comparison of the simulation results with measured pressure log data shows good agreement. Simulation studies for the fluid flow in a wellbore with variable diameter occurring due to calcite scaling shows higher mass transfer rate and wall normal bubble flux in the region of scaling, resulting in higher chances of mineral precipitation and deposition in the same region.