TY - JOUR

T1 - Decomposition Kinetics and Self-Preservation of Methane Hydrate Particles in Crude Oil Dispersions

T2 - Experiments and Theory

AU - Sizikov, Artem A.

AU - Vlasov, Valeriy A.

AU - Stoporev, Andrey S.

AU - Manakov, Andrey Yu

N1 - Publisher Copyright: Copyright © 2019 American Chemical Society.

PY - 2019/12/19

Y1 - 2019/12/19

N2 - The self-preservation phenomenon may be used for storage and transportation of natural gas in the form of gas hydrate. In this work, decomposition kinetics and self-preservation of methane hydrate dispersions in two types of crude oils were studied. Hydrate particle sizes in both dispersions did not exceed 30 μm. The experiments were performed at constant temperatures from-4 to-20 °C without preliminary deep-freezing of the samples. The kinetic curves of the methane hydrate decomposition were recorded as depending on methane pressure in the autoclave vs time. In the experiments with the first dispersion, it was shown that at the decomposition degree of 50%, the hydrate decomposition rates decreased by 1-2 orders of magnitude in comparison to the rates at the start of the decomposition process; therefore, hydrate self-preservation took place. Estimated thickness of the ice shell providing self-preservation did not exceed 1.3 μm at the decomposition degree of 50%. Self-preservation was less pronounced in experiments with the second dispersion. It may be explained by the presence of the surfactant in the second dispersion, which was added to stabilize the water-in-oil emulsion from which the dispersion was obtained. Possible mechanisms and the effect of various factors on the efficiency of self-preservation are discussed in this work. A mathematical model of hydrate decomposition process taking into account self-preservation of hydrate particles in the dispersion is suggested. A time-dependent (decreasing) diffusion coefficient of methane in ice shell was used in the model.

AB - The self-preservation phenomenon may be used for storage and transportation of natural gas in the form of gas hydrate. In this work, decomposition kinetics and self-preservation of methane hydrate dispersions in two types of crude oils were studied. Hydrate particle sizes in both dispersions did not exceed 30 μm. The experiments were performed at constant temperatures from-4 to-20 °C without preliminary deep-freezing of the samples. The kinetic curves of the methane hydrate decomposition were recorded as depending on methane pressure in the autoclave vs time. In the experiments with the first dispersion, it was shown that at the decomposition degree of 50%, the hydrate decomposition rates decreased by 1-2 orders of magnitude in comparison to the rates at the start of the decomposition process; therefore, hydrate self-preservation took place. Estimated thickness of the ice shell providing self-preservation did not exceed 1.3 μm at the decomposition degree of 50%. Self-preservation was less pronounced in experiments with the second dispersion. It may be explained by the presence of the surfactant in the second dispersion, which was added to stabilize the water-in-oil emulsion from which the dispersion was obtained. Possible mechanisms and the effect of various factors on the efficiency of self-preservation are discussed in this work. A mathematical model of hydrate decomposition process taking into account self-preservation of hydrate particles in the dispersion is suggested. A time-dependent (decreasing) diffusion coefficient of methane in ice shell was used in the model.

KW - GAS HYDRATE

KW - NATURAL-GAS

KW - DIFFUSION-COEFFICIENTS

KW - CLATHRATE HYDRATE

KW - CARBON-DIOXIDE

KW - LIQUID HYDROCARBONS

KW - CO2 CAPTURE

KW - ICE

KW - DISSOCIATION

KW - STORAGE

UR - http://www.scopus.com/inward/record.url?scp=85076405406&partnerID=8YFLogxK

U2 - 10.1021/acs.energyfuels.9b03391

DO - 10.1021/acs.energyfuels.9b03391

M3 - Article

AN - SCOPUS:85076405406

VL - 33

SP - 12353

EP - 12365

JO - Energy & Fuels

JF - Energy & Fuels

SN - 0887-0624

IS - 12

ER -