Study on the Formation Characteristics of CO₂ Hydrate and the Rheological Properties of Slurry in a Flow System Containing Surfactants

Abstract

Adding low dosage hydrate inhibitors to the hydrate systems makes the generated hydrate particles more uniformly dispersed in the liquid phase, which can significantly reduce the hydrate accumulation and blockage in oil and gas pipelines. The effect of surfactant hydrophile–lipophilic balance (HLB) values on hydrate flow characteristics was studied with a flow loop. The experimental results showed that there was a critical HLB value. When the HLB value was 4.3–9.2, it had an inhibitory effect on the hydrate induction time, and when the HLB value was greater than 10.2, it had a promoting effect. The hydrate volume fraction increased gradually with the increase in the HLB value, while the slurry apparent viscosity decreased with the increase in the HLB value. It was also found that different types of surfactants all showed the effects of anti-agglomerant and dispersion, which can obviously improve the flow of the hydrate slurry. Finally, the analyzed results showed that the hydrate slurry exhibited shear-thinning behaviors that can be identified as a pseudoplastic fluid based on the Herschel–Bulkley rheological model, and the functional relationship between the rheological index and the solid phase hydrate volume fraction was obtained using the fitting method. This study can provide a reference for the preparation of high-efficiency hydrate anti-agglomerants.

Comprehensive Review and Perspectives of CO2 Hydrate Storage in Subseafloor Saline Sediments: Formation, Stability, and Optimization Strategies

“…Studies have further shown that water-based nanofluid particles can enhance the number of hydrate nucleation sites and promote heterogeneous nucleation. 23,206 This increases the rate of hydrate nucleation and shortens the induction time for hydrate formation. 23 Furthermore, the addition of kinetic accelerators or promoters, as mentioned in various studies, has proven beneficial in improving the efficiency of hydrate formation by optimizing the crystallization process.…”

Formation Mechanism of CO2 and CH4 Hydrates in Bubbly Flow in a Horizontal Pipeline

“…The hydrate formation, agglomeration, and deposition were observed experimentally in their works . Lv et al experimentally investigated the CO 2 hydrate formation and flow characteristics in the gas–oil–water flow system . The effect of the surfactant could make hydrate particles disperse in the liquid phase more uniformly .…”

“…However, for hydrate formation in a bubble column or bubble flow, the environment becomes a gas–liquid two-phase flow condition. Different from the hydrate formation on the single bubble, the hydrate shell would be broken by the effect of the high-speed flow during the hydrate formation, which makes formation characteristics much more complex. − Luo et al used a single pipe with a stirrer to investigate the tetrahydrofuran hydrate formation in a bubble column in the static aqueous solution . Shimizu et al experimentally investigated the methane hydrate formation processes in the methane–water bubbly flow using a flow loop .…”

“…29 Lv et al experimentally investigated the CO 2 hydrate formation and flow characteristics in the gas−oil− water flow system. 30 The effect of the surfactant could make hydrate particles disperse in the liquid phase more uniformly. 30 Liao et al analyzed the inhibition effect of thermodynamic inhibitors, kinetic inhibitors, and their compound systems on methane hydrate formation by the experiments and molecular simulations from macro-and microscopic views.…”

“…30 The effect of the surfactant could make hydrate particles disperse in the liquid phase more uniformly. 30 Liao et al analyzed the inhibition effect of thermodynamic inhibitors, kinetic inhibitors, and their compound systems on methane hydrate formation by the experiments and molecular simulations from macro-and microscopic views. 3 They pointed out that the thermodynamic inhibitor limited the motion of water molecules and reduced the steric effects of the kinetic inhibitor, where the phenomena enhanced the effect of inhibitors on methane molecules.…”