Static and dynamic evaluation of formation damage due to barium sulfate scale during water injection in carbonate reservoirs

Abstract

One of the major challenges during water injection into oil reservoirs is mineral scales formation. Barium sulfate is one of the hardest inorganic scales in oil fields and insoluble in chemical solvents. Therefore, in this study, the formation conditions of barium sulfate scale were investigated. The experiments were performed in two parts including static and dynamic compatibility tests and the impact of brines volume ratio, temperature, pH, and salinity of injection water were explored. In addition, the scale formation tendency was simulated and the results were compared with the measured data. The results of static experiments indicated that the maximum amount of barium sulfate scale equals 63 mg/l forms at 90% formation water. Comparing the results of static and dynamic compatibility tests revealed that the increase of pH value increases barium sulfate scale in dynamic tests while having no effect in static experiments. This finding confirms that a different scale formation mechanism prevails in the presence of reservoir rock. The experimental results also approve that the amount of barium sulfate scale decreases by reducing the salinity of injection water, so that by diluting injection water 5 times, the maximum amount of scale decreased 21% and 44% at ambient and reservoir temperatures, respectively. The findings of this study help for better determination of water properties to increase the efficiency of water injection operations, enhance oil production and simultaneously diminish formation damage. Concurrent assessment of static and dynamic tests leads to determining the dominant mechanisms of scale formation in the presence of reservoir rock which helps to select the appropriate remediation methods.