Influence of Regenerated Monoethylene Glycol on Natural Gas Hydrate Formation

Abstract

The key objective of this study is to investigate the efficiency of thermodynamic hydrate inhibition of monoethylene glycol (MEG) solutions collected from a MEG regeneration/reclamation pilot plant, simulating six scenarios of the start-up and clean-up phases of a typical gas field. The scenarios contain complex solutions of condensates, drilling muds/well completion fluids with high concentrations of divalent-monovalent ions, particulates, and various production chemicals, which can result in various system upsets in a MEG plant. MEG was regenerated and reclaimed at a recently constructed closed-loop MEG pilot plant that replicates a typical field plant. During MEG plant operation, feed-rich MEG is separated, cleaned, and heated so that water in it is evaporated and purified for reuse. In this study, equilibrium conditions of natural gas hydrates in the presence of 20 wt % of regenerated and reclaimed MEG solution at a pressure range of 65-125 bar were reported. The equilibrium data were measured in a PVT sapphire cell unit using an isochoric temperature search method. The measured data were compared with the literature and theoretical predictions to investigate the influence of regenerated/reclaimed MEG on gas hydrate inhibition performance. A better understanding of the efficiency of regenerated complex MEG solutions on hydrate phase equilibria forms a basis for improved system design, operations, and calculating required MEG dosages for hydrate inhibition.