Effects of hydrophilic and hydrophobic nano‐CaCO₃ on kinetics of hydrate formation

Abstract

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Molecular Insights into the Impacts of Calcite Nanoparticles on Methane Hydrate Formation

“…Therefore, our findings indicate that calcite NPs will inhibit methane hydrate nucleation whenever the methane composition in solution is fixed by its solubility, as with water/gas two-phase systems. Our results thus give evidence for the experimental observations that hydrophilic NP inhibited hydrate nucleation because of its hydrophilicity, and if the weight percentage of nanoparticles in solution was fixed, the smaller the nanoparticle, the stronger the inhibition effect. , …”

“…It can explain the experimental conjecture that the agglomeration of nanoparticles can alter the surface wettability, thus influencing the inhibition effects. 25,26 We note that in the above system, when two NPs were inserted in the system, the mole fraction of methane molecules away from the NPs is increased due to an enhanced exclude-volume effect because the overall number of molecules was fixed. However, if a bulk gas phase is used in the configuration, the overall mole fraction of methane molecules in the solution is expected to be reduced (i.e., the methane composition in solution is fixed by its solubility).…”

“…Our results thus give evidence for the experimental observations that hydrophilic NP inhibited hydrate nucleation because of its hydrophilicity, and if the weight percentage of nanoparticles in solution was fixed, the smaller the nanoparticle, the stronger the inhibition effect. 25,26 In addition, in order to probe limiting behavior of large particles, a flat calcite interface system was used to simulate methane hydrate nucleation under the same conditions as that of the above nucleation simulations. One can see from Figure S5 in the Supporting Information that there is a low methane concentration close to the calcite surface and methane hydrate nucleates away from the calcite slab, which agrees with the results shown in Figures 4 and 5.…”

“…Meanwhile, the high-pressure drilling fluids might also stimulate gas hydrate reformation, thus causing safety issues in the well. To solve the above-stated problem, nanoparticles (NPs) have been proposed for addition to the drilling fluids commonly applied in oil and gas well drillings. − The NPs are expected to enhance the strength of filter cake formed by drilling fluid, thus hindering the invasion of the drilling fluid and maintaining the stability of the wellbore and hydrate reservoirs. However, a possible side effect of the addition of NPs is that the NPs may influence hydrate formation and decomposition.…”

Research progress on the effects of nanoparticles on gas hydrate formation

“…They pointed out that the inhibition was related to the hydrophilicity. Similarly, Guo et al 54 concluded that although CaCO 3 nanoparticles promoted the formation of hydrate, the hydrophilic CaCO 3 nanoparticles aer modication inhibited the formation of hydrate. Xu et al 55 conducted wellbore simulation experiments and showed that the inhibition effect of the hydrophilic SiO 2 on hydrate in the wellbore increased with the increase in particle size.…”