Prediction of Permeability Reduction Rate Due to Calcium Sulfate Scale Formation in Porous Media

Abstract

Abstract Water injection is usually associated with various types of mineral scale formation and deposition which significantly undermine the performance of the injection by changing some reservoir properties such as permeability and porosity. Mineral scale deposition in surface and subsurface petroleum streams is one of the main concerns affecting the economy and safety of any production scenarios. Among various types of mineral scales, calcium sulfate is one of major scales in petroleum industry that can cause sever flow assurance and formation damage issues. Many parameters are affecting this problem. Temperature, pressure, fluid concentration, ratio of brine to hydrocarbon, fluid dynamic and type of porous media are among these parameters. Interpretation and prediction of permeability reduction in such complicated system is very complex. In this work an experimental and theoretical study has been conducted to investigate the permeability reduction due to CaSO4 scale formation. For this purpose, brine solutions containing calcium and sulfate ions were injected in a packed glass beads porous media at elevated temperatures and various flow rate and brine concentrations. The pressure decline and permeability changes were measured in all the conducted tests. It was found that the permeability reduction by calcium sulfate scale formation follows a systematic trend considering various above mentioned important parameters. Hence, a novel empirical equation has been suggested, which can predict permeability reduction rate with high accuracy to experimental data.