A novel approach for produced water treatment: Supercritical water oxidation and desalination

Abstract

Produced water generated from oil and gas operations contains significant quantities of environmentally hazardous hydrocarbons, organic chemicals, and inorganic salts. Environmental regulations with impaired water disposal mandates produced water treatment and desalination. Industry standard desalination technologies are energy-intensive and mandate extensive produced water pre-treatment including removal of hydrocarbons constituents for efficient operations. This study investigates a novel process intensification approach integrating supercritical water oxidation (SCWO) unit operation with a supercritical water desalination (SCWD) process for energy efficient produced water treatment and desalination. The coupled SCWD-SCWO process is found to be very energy-efficient and cost effective than existing industry standard desalination technologies. For energy efficient operation, the heat generated from the SCWO of hydrocarbons present in the produced water is used for power generation using a high efficiency and low-cost re-heat Rankine cycle process. The cost of treating produced water with proposed SCWO-SCWD process is independent of the salt concentration. The proposed process has the potential to offer step-change improvements over conventional processes in both the efficiency and cost of produced water treatment: for example, a cost and energy saving of 70% and 100% is calculated for the treatment of produced water containing 250 g/l salt and 10.6 g/l hydrocarbon.