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A comparative investigation of methane hydrate formation from 0.1 wt % solutions of an alkaline extract of humic acids (HA) and sodium dodecyl sulfate (SDS) has been carried out. It was demonstrated that the hydrate grows as a voluminous loose mass squeezed onto the reactor walls in both cases. It turns that about 75% of water transforms into hydrate within 15−20 min. Thus, natural HA can act as kinetic hydrate promoters. At the same time, SDS increases the hydrate nucleation rate compared to pure water under the studied conditions (12.5−13.0 MPa and −5 °C), while HA retards the hydrate nucleation. Visual observation of the hydrate growth in the solutions of HA and SDS allowed us to propose a new mechanism of hydrate growth in the form of a porous loose mass squeezed upward over the reactor walls. The mechanism relates to overgrowing of the hydrate film formed at the gas−solution interface into the solution volume. This results in squeezing some part of the solution onto the reactor walls. Simultaneous contact of the gas, solution, and hydrate facilitates the rapid transformation of the squeezing solution into a loose hydrate mass. Then this mass soaks up the solution due to the capillary forces.

Isothermal nucleation of methane hydrate in the emulsions of water in oil has been studied experimentally at a pressure of 12.5 MPa within the temperature range of −3.0 to −4.9 °C (supercooling 17.8−19.7 °C). It was demonstrated that the experimental survival curves are composed of two regions with different slopes to the time axis. Nucleation rates calculated for initial and final (in parentheses) regions of survival curves turned out to be equal to 0.00065 (0.00055), 0.00036 (0.00017), and 0.00018 (0.00010) s −1 m −2 for temperatures −4.9, −4.0, and −3.0 °C, respectively. The experimental data were extrapolated to the regions of higher and lower supercooling values using a known expression describing the dependence of the nucleation rate on temperature. It may be expected that the information concerning the temperature dependence of hydrate nucleation rates in water−oil systems will be useful to optimize the consumption of kinetic hydrate inhibitors during the development of oil and gas deposits.