Effect of Temperature on the Rate of Methane Hydrate Nucleation in Water-in-Crude Oil Emulsion

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 degrees C (supercooling 17.8-19.7 degrees 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 degrees 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.