Simple mathematical model for predicting anhydrite calcium sulfate scale deposition in brines

A simple and reliable method has been developed to predict the solubility of anhydrite calcium sulfate in NaCl-water solutions over wide range of temperature (100-325°C) and pressure (up to 500 bar). The scaling tendency prediction model is based on sound literature experimental equilibrium solubility of anhydrite calcium sulfate in NaCl-water system under variable pressures and temperatures. The validity of the predictive method has been examined and compared to literature data and other related models, and the estimations of error in analysis has been presented. The predicted results are in basically conformity with literature solubilities which corroborate the suitability and applicability of the model. The predictive method is simple, easy to use and designed for environments where anhydrite calcium sulfate scale occurs.