The System CaCl₂–H₂O: Thermodynamic Modeling and Flow Calorimetry Experiments at Elevated Temperatures and Pressures

Abstract

Produced water from oil and natural gas production is challenging to treat due to its high salinity. Such brines are often a mixture of various mono-and divalent-cation salts, and elevated pressure methods near water's critical point to reclaim reusable water from the brines for reuse are of growing interest. Modeling efforts have traditionally focused on NaCl−H 2 O systems, which potentially introduces considerable calculation error when simulating multi-component salt solutions. This study considers the thermodynamic characteristics of the CaCl 2 −H 2 O system to aid in this effort. A series of correlations are presented for the critical pressure line and composition, vapor−liquid equilibria around the critical line, and specific volume and enthalpy for high-temperature and pressure CaCl 2 −H 2 O systems. In addition, heat capacity data for CaCl 2 −H 2 O are presented near the critical line to assist in the determination of the specific enthalpy correlation, with mass fractions from 0.1 to 0.2, pressure from 23 to 26 MPa, and temperatures from 582 to 625 K.