An Analysis of Likely Scalants in the Treatment of Produced Water from Nova Scotia

Abstract

A significant barrier to further use of hydraulic fracturing to recover shale oil and/or gas is the treatment and/or disposal of hypersaline produced water. This work is an analysis of produced water from Nova Scotia, with the aim of understanding how scale impacts the choice of desalination system used in its treatment. Four water samples are presented, and for a representative case, the supersaturation of some likely scalants is estimated as a function of temperature, recovery ratio, and pH. This supersaturation map is then compared to conditions representative of common desalination systems, allowing the identification of limitations imposed by the water's composition. In contrast to many natural waters, it is found that sodium chloride is the most likely first solid to form at high recovery ratios, and that the top temperature of thermal desalination systems is unlikely to be scale-limited in the treatment of these waters.