Study on the mixed deposition rate and phase transition thermodynamic parameters of crude oil wax crystals and hydrates

Abstract

Throughout the development of deepwater oil and gas fields, the occurrence of mixed deposition involving wax and hydrate is a prevalent phenomenon. To understand this process, researchers have explored the kinetics and thermodynamic behavior governing the co-deposition of wax and hydrates. It was observed that the Gibbs free energy change of hydrate increases with increasing pressure, while the entropy change experiences a decrease under heightened pressure conditions. The Gibbs free energy change and entropy change of wax crystal precipitation exhibit an increase with rising wax concentration. In a 100 mL sample of simulated crude oil containing 10 vol% moisture and 2.5 wt% wax, the rate of solid phase deposition measures 0.1126 cm³/min when the temperature drops from 61 °C to 2 °C. The results exhibit that the dispersion of wax crystals within the oil phase serves to inhibit aggregation phenomenon during hydrate formation and can be effectively used to inhibit hydrate deposition.