Method for determining equilibrium thermobaric parameters of the existence of liquefied gas hydrates

In comparison with gas hydrates, the issue of describing liquefied gas hydrates has received much less attention, which is due to the low content of condensed gases in natural gas mixtures. However, with the growth of technological requirements for the development of gas and gas-condensate fields, as well as for better collection and preparation of well products, it is important to describe the behavior of hydrates in various thermobaric conditions. This article proposes a new method for determining the equilibrium temperatures and pressures of the existence of condensate hydrates. The method involves determining the thermobaric conditions of the existence of each component in the hydrate-forming system of hydrates according to the calculated dependencies taking into account the coefficients. Within the framework of the article, the authors verified the proposed mathematical dependencies with the available experimental data. The comparison of the data obtained using the proposed model with the known experimental data shows that the average error in determining the thermobaric parameters for individual hydrate formers (ethane, propane, isobutane, cyclopentane, carbon dioxide and hydrogen sulfide) is 4 %. There are comparatively few data for liquefied gas mixtures; however, when the proposed method is used, the average discrepancy between the data for a liquefied propane-butane mixture and the known experimental data is 2.48 %. The demonstrated accuracy confirms the reliability of the proposed method for its use in solving various technological problems. The developed generalized method for calculating the equilibrium thermobaric conditions of the condensate hydrates existence, which implies determining the thermobaric parameters of a hydrate-forming system using the calculated dependencies taking into account the proposed coefficients, is a potentially important addition to the existing theoretical base devoted to describing the states of hydrate-forming systems.