Mathematical Modelling of Formation Damage in Geothermal Wells Due to Fines Migration

Abstract

A mathematical model for fines migration during exploitation of geothermal wells is developed. Governing equations in the proposed model describe the flow of water with fines towards the well accounting for particle detachment, migration and straining, which result in permeability decline and well impedance growth. The developed model for well inflow performance has been applied to the field case (geothermal reservoir B, Australia) successfully. The well impedance history obtained from model prediction and from field measurements are in good agreement, which validates the current model. The sensitivity analysis of the flow rate and the temperature reveals that increase of either the flow rate or the temperature worsens the formation damage and well impedance. Geothermal reservoirs are significantly more perceptive for fines migration induced formation damage than traditional oil and gas reservoirs, due to substantial decrease in electrostatic particle-rock attachment at elevated temperature.