A comprehensive thermodynamic model for high salinity produced waters

• Published in: AIChE journal Vol. 66; no. 1
• Main Authors: Tanveer, Sheik, Chen, Chau‐Chyun
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-01-2020; American Institute of Chemical Engineers
• Subjects: aqueous electrolytes; Calcium; Calcium ions; electrolyte NRTL model; Electrolytes; Gas production; hexary oceanic salt systems; Interaction parameters; Magnesium; Oil and gas production; Parameter identification; Phase equilibria; Salinity; Salinity effects; salt solubility; Separation techniques; Subsystems; Thermodynamic equilibrium; Thermodynamic models; thermodynamic properties
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.16818

Reuse of produced waters in oil and gas production is a major concern due to high treatment cost and regulations on disposal in the environment. To support development of separation techniques and process innovations, we report a comprehensive thermodynamic model for the aqueous hexary system of Na+, K+, Mg2+, Ca2+, Cl−, and SO42−, the major ionic species present in high salinity produced waters. Based on the electrolyte NRTL theory, the model accurately calculates thermodynamic and phase equilibrium properties with two binary interaction parameters per water‐electrolyte pair and electrolyte‐electrolyte pair sharing a common ion. This article presents the methodology to identify the binary interaction parameters from literature data and the model results for wide varieties of thermodynamic and phase equilibrium properties including salt solubility for selected binary, ternary, quaternary, and quinary subsystems. The model is validated with the electrolyte concentrations up to salt saturation and temperatures from 273 to 473 K.