Stabilization mechanism of condensate oil droplets in oil-bearing rich monoethylene glycol from deepwater oil and gas fields

The treatment of oil-bearing rich monoethylene glycol (MEG) is a critical link in ensuring the normal development of deepwater oil and gas fields. The stabilization mechanism of condensate oil droplets is vital for the design of separators and the selection of demulsifiers. However, studies on this topic remain scarce. In this paper, the effects of monoethylene glycol (MEG) concentration and inorganic salt concentration on the stability of condensate oil droplets in rich MEG were systematically investigated. The oil droplet stabilization mechanism was analyzed from the perspective of interfacial properties by measuring interfacial tension (IFT), zeta potential, interfacial elastic modulus, and interfacial thickness. Macroscopic stability evaluation experiments indicated that: in the absence of inorganic salts, oil droplet stability gradually decreased with increasing MEG concentration; in the presence of NaCl, oil droplet stability gradually increased with rising MEG concentration; and with a constant MEG concentration, oil droplet stability decreased as NaCl concentration increased. Interfacial property analysis revealed that MEG and NaCl had minor effects on IFT and zeta potential. They primarily influenced the interfacial thickness, resulting in changes in the interfacial elastic modulus (taking a NaCl concentration of 10,000 mg/L as an example, as the MEG concentration increased from 0% to 50%, the interface thickness gradually increased from 4.50 Å to 4.94 Å, and the elastic modulus increased from 3.38 mN/m to 4.84 mN/m), thereby affecting oil droplet stability.