Phase Equilibrium of Carbon Dioxide Hydrates Inhibited with MEG and NaCl above the Upper Quadruple Point

This is the authors' abstract. We don't add key points for this paper.

Exploration of oil fields with high concentrations of carbon dioxide brings new challenges to the oil and gas industry. The high pressures reached in production pipelines can cause the condensation of the gas phase, characterizing the appearance of an upper quadruple point in the hydrate phase diagram. To prevent the formation of hydrates, the use of thermodynamic inhibitors, such as alcohols and glycols, is common in the industry. In addition, water from oil production is naturally inhibited with salts, such as NaCl. In this work, equilibrium data not previously reported for CO 2 hydrates inhibited with MEG and NaCl were determined for pressures between 8.5 and 25 MPa using an isobaric experimental procedure. By the Clausius–Clapeyron relation and concepts of water activity, the consistency of the data was evaluated with promising results. A comparison of the measured data obtained in this work with prediction tools (Multiflash, PVTsim, and CSMGem) and the model by Sirino et al. 30 [ Fluid Phase Equilib. 2018, 475, 45−63] was done.