Integrated investigation on the nucleation and growing process of hydrate in W/O emulsion containing asphaltene

Abstract

During the production and transportation of deep-water oil and gas, the low-temperature and high-pressure operating environment might induce hydrate formation and eventual blockage, which poses a serious threat to the flow assurance. Furthermore, the formation, aggregation and deposition characteristics of hydrate would become more complicated in the presence of asphaltene. Consequently, clarifying the effect of asphaltene on hydrate nucleation and growing process plays an important role in the safety production and flow assurance of deep-water oil and gas field. The kinetic characterizations of hydrate nucleation and growth in W/O systems containing asphaltene were investigated via experimental research, molecular dynamics simulations and mathematical modeling. Results revealed that the hydrate nucleation induction time increased with the increase of asphaltene content. The inhibition of hydrate nucleation by asphaltene in high-pressure (5 MPa) experiments was more pronounced than that in low-pressure (3 MPa). On the other hand, asphaltene restrained hydrate formation and the total gas consumption decreased with the increase of asphaltene content. The dynamic adsorption process of asphaltene at oil–water interface and the evolution of the surface coverage with time were elucidated by jointly solving the Ward-Tordai and Langmuir equation. Combined with the above aspects, the induction time model containing asphaltene was developed, which could provide a new perspective and methodology for deep-water flow assurance