Influence of Fractions Isolated from Crude Oils and Refined Petroleum Product on Decomposition Process of Methane Hydrate

Decomposition of methane hydrate in systems containing asphaltenes, resins, or oils isolated from two types of crude petroleum and transformer oil has been studied. To prepare a sample of methane hydrate suspension in a fraction isolated, a pure hydrate powder with water to hydrate conversion of 0.92 ± 0.08 was used. The hydrate powder with particle size less than 250 μm was mixed with the powdered fractions at the liquid nitrogen temperature. Then the mixture was heated to melt the fractions and allow their components to be adsorbed on the hydrate particles surface. All stages of suspension preparation were carried out in the hydrate stability zone. Similar studies with hydrate particles suspended in saturated/aromatic components and solutions of polar compounds isolated from petroleum/transformer oils as well as in n-decane/toluene were also carried out. As a result, it has been found that fraction of oils as well as its subfraction of saturated hydrocarbons contribute to the manifestation of methane hydrate self-preservation effect. Fourier transform infrared and gas chromatography-mass spectrometry analyses of the fractions showed that the self-preservation took place in systems containing hydrate particles among a mixture of isoalkanes. The data obtained contribute to a comprehensive understanding of the self-preservation phenomenon.