Characterization of Hydrate Formation and Flow Influenced by Hydrophilic–Hydrophobic Components within a Fully Visual Rocking Cell

Abstract

The intricate interplay of crude oil composition and additives critically affects hydrate formation and flow behavior, which is significant for flow assurance particularly in deepwater. To investigate, we varied the hydrophilic and hydrophobic properties by proportioning two nonionic surfactants (Span 80 and Tween 80) and conducting hydrate formation experiments in a visual rocking cell. The results show that the increasing hydrophilic−lipophilic balance (HLB) value shifted emulsions from water-in-oil to multiple and oil-in-water phases and significantly affected the hydrate formation among different emulsion types, with a marked increase in the hydrate formation rate in the HLB range of 9 to 11. Slurries maintained flowability due to low hydrate conversion, yet higher HLB (>11) led to slight agglomeration and deposition. In addition, the impacts of water conversion were investigated by multiple pressurization, showing that the hydrate formation amount affected slurry flowability but was primarily dependent on the hydrophilicity and hydrophobicity of the surfactants. When the HLB was below 11, the final water conversion was about 80%, but the formed hydrate still exhibited good dispersion and flowability. In contrast, HLB exceeding 13 resulted in extensive adhesion and deposition on the cell walls. When the water conversion reached about 40%, flowability was completely lost and hydrate blockage occurred.

Crystal Growth of CO2–CH4 Hydrate on a Solid Surface with Varying Wettability in the Presence of PVCap

“…Clathrate hydrates are nonstoichiometric cage-like crystalline compounds formed by gas molecules trapped in water molecules under low temperatures and high pressures . Hydrates have the advantages of high calorific value and strong gas storage capacity, which has led to extensive research in the utilization of hydrate technology. − However, natural gas hydrate formation is harmful in some cases, such as during the process of gas and oil transportation, where hydrate formation can cause serious economic loss and safety problems. − …”

Phase Transition Characteristics of Hydrate Formation Process in Microscale Pores

“…In recent years, there has been significant advancement and enrichment in visualization techniques, , with the utilization of X-ray − or optical microscopy, − emerging as a prevailing research trend for studying the formation dynamics of hydrates. Rui et al observed that under gas-filled conditions, as the water migration rate increases, the hydraulic stability transitions from grain-coating hydrate to grain-filling hydrate and finally to load-bearing hydrate.…”