METHANE HYDRATES NUCLEATION, GROWTH, AND DISSOCIATION: AN IN-DEPTH COMPARISON BETWEEN EXPERIMENTAL EVIDENCES AND THE CURRENT THEORY

Abstract

Methane hydrates nucleation, massive growth, and dissociation were tested in a small-scale experimental apparatus. The whole process was accurately described: the pressure and temperature trend over time, together with the relation existing between pressure and temperature, allowed one to distinguish seven different phases. As for nucleation, three steps were observed, while the other processes were divided into two parts. The results were compared with the data present in the literature (mainly referred to nucleation): a very strong correlation was found even if analyses were based on different approaches. Moreover, we found the existence of some not completely defined characterizations of the process, mainly related to the last portion of massive growth. Finally, the hydrate formation rate and its variation found during consecutive measurements were evaluated. This latter study confirmed what was asserted previously and strongly agrees with the labile cluster theory. Moreover, it justified the apparent incongruence between the formation rate and moles of hydrates formed in the initial nucleation phase.