Rheology investigation of propane gas hydrate crystallization in water/asphaltene-resin-wax deposit emulsions

Abstract

Hydrates and asphaltene-resin-wax deposits are increasingly concerned as a terrible problem in the field of offshore oil and gas production and transportation. The rheological property of propane gas hydrate in the water-in-asphaltene-resin-wax deposit (W/ARWD) emulsion was in situ characterized by experiments in a stress-controlled rheometer with particular focus on the effects of pressure, emulsion component ratio, and deposit composition. Results demonstrated that the higher pressure could accelerate hydrate formation and aggregation in a shorter time, and exhibit more obvious shear-thinning behavior of hydrate slurry. The emulsion component ratio was positive correlation with the hydrate slurry viscosity and the yield stress, was negative correlation with the hydrate crystallization time. Asphaltene and wax occupied more nucleation sites on water droplets and formed physical barriers to hinder the hydrate crystallization. The promoting effect of resin on hydrate crystallization was stronger than inhibiting effect. With the increase of asphaltene, resin, and wax contents, the yield stress of hydrate slurry gradually increased, and the effect of wax on the yield stress was stronger than asphaltene and resin, which was associated with the multiple effects of capillary bridge between hydrate particles and spatial network of wax crystals. Furthermore, the coupling effect of pressure, emulsion component ratio, and deposit composition on the rheological properties of hydrate slurry had been studied. This study is significant in that it can helpfully support the development of subsea multiphase flow assurance in petroleum production.