Today, considering the increasing economic efficiency and reducing the natural exploitation of oil, the use of oil recovery methods is more important. However, this method is usually associated with the formation of mineral deposits in oil fields. The amount and location of the formation of mineral deposits depends on factors such as temperature, pressure, solubility. Barium sulfate, calcium sulfate and strontium sulfate are one of the most important mineral deposits in oil systems. There are mineral deposits from hydrocarbon reservoirs to surface and sub-surface installations in the oil industry. Considering the increasing use of oil recovery methods for optimal oil use, the formation process and methods for removing mineral deposits are of great importance. Therefore, in this book, due to the problems of mineral sediments in petroleum systems, thermodynamic properties such as solubility of mineral compounds, water activity and saturation index in electrolytic systems of aqueoussolutions are analyzed and Study of formation of mineral deposits in oil wells is considered according to thermodynamic models.