Research into peculiarities of phase transitions during the dissociation of gas hydrates
Purpose. Analytical study of the dissociation process of gas hydrates taking into account the peculiarities of phase transitions occurring during their dissociation and described by the Clausius-Clapeyron equation. Methods. The research uses an integrated approach, which includes the analysis and generalization of literature sources devoted to studying the peculiarities and thermobaric properties of gas hydrates; processes of hydrate formation and accumulation; methods for the development of gas hydrate deposits and technologies for extracting the methane gas from them; analytical calculations of phase transitions of gas hydrates. Findings. The conditions for the formation of gas hydrate deposits have been analyzed and the peculiarities of stable existence of gas hydrates have been revealed. The existing experience in the development of gas hydrate technologies by leading scientists, world research laboratories, advanced design institutes and organizations is summarized. The mechanism of hydration formation in rocks is studied and some classifications of gas hydrate deposits occurring in sedimentary rock stratum are presented. It has been determined that gas hydrates in natural conditions usually occur not only in the form of pure hydrate reservoirs, but most often contain a certain share of rock intercalations, which makes the deposit structure heterogeneous. The mechanisms of hydrate formation and dissociation of gas hydrates have been revealed. It has been determined that the Clausius-Clapeyron equation in a modified form can be used to describe phase transitions both during the formation and dissociation of gas hydrates, taking into account the deposit heterogeneity. Originality. The Clausius-Clapeyron equation for the analysis of phase transformations in solid phases during hydrate formation and dissociation of gas hydrates is defined more exactly, taking into account the consumption of additional heat due to the influence of the properties of rock intercalations. Practical implications. The research results are useful for designing the rational thermobaric parameters (pressure and temperature) in the dissociation of natural or technogenic gas hydrates, as well as for optimal control of the kinetics of the process.