Thermodynamic Prediction of Ba and Sr Sulphates Scale Formation in Water Flooding Projects In Oil Reservoirs

Nowadays, recovery operations in oil reservoirs through water injection have a favourable economic approach, but the efficiency of this method decreases due to the formation of mineral deposits in super saturation. In the present study, formation of mineral deposits of barium sulphate and strontium sulphate has been studied and predicted during water imbibition operation in several oil fields such as Nosrat and Siri, according to the Extended UNICQUAC activity factor model. Based on the results of this study, the Extended UNIQUAC model is well matched to experimental and field results. Also, the prediction of barium sulphate and strontium sulphate precipitation in Nosrat oilfield depends on the conditions and composition of formation water, injected water (Persian Gulf water) and operational conditions, which can cause problems in surface and sub-surface equipment in oil exploitation operations. But for the Siri oil field, based on the analysis of water and operational data, the precipitation of barium sulphate and strontium sulphate is not significant. In this study, the temperature is 50, 100 and 110 °C, and also the pressure is 135, 270 and 2465 psi. The concentration of mineral salts in the water sample and injection water was up to 86,900 mg / l.