Saline produced water treatment using gas hydrates

Formation of gas hydrate can be considered as a suitable method of produced water desalination. In this study, CO2 hydrate formation experiments with different produced water samples were conducted at approximately 3.5 MPa and 274.2 K. After hydrate formation, the concentrated salty water was extracted from the reactor and the formed hydrate was washed with a suitable amount of fresh water to improve salt removal effectively and finally hydrate was dissociated to produce fresh water. Removal efficiency for dissolved mineral components in the produced water samples was also examined. It was concluded that with a three-stage hydrate process, 82-89.2% of dissolved minerals will be excluded. This study illustrated that the CO2 hydrate - based desalination can be used for produced waters with total dissolved solids less than 160,000 mg/L.