Decrease in Reservoir Permeability due to Deposition of Silica Dissolved in Geothermal Injection Water

Numerical Simulation in a Radial Flow System

Abstract

A mathematical model to simulate permeability decrease caused by the depositionof silica in a reservoir near an injection well has been developed. Isothermal and steady state water flow is assumed in the reservoir. Sensitivity study has been carried out with the model under injecting geothermal water of 90 degree C and of 522 mg/l mono-silicic acid at a constant injection rate, 60m³/h. Reservoir porosity gives serious effect both on the injectivity decrease of the well and on the extention of permeability damaged area due to the silica deposition. Reservoir thickness also gives the effect on the injectivity decrease with time.