RATIONALE FOR CHOOSING CORRELATIONS FOR GAS HYDRATE FORMATION TEMPERATURE COMPUTATION FOR GASES OF VARIOUS COMPOSITIONS

Abstract

Gas hydrates are the object of continuous research in the oil and gas industry. Gas hydrates can form in gas production systems: in the bottomhole zone, in the wellbores, in plumes and infield reservoirs, in gas treatment systems, as well as in main gas transport systems, causing serious problems associated with the disruption of these processes. However, recently, the gas industry has found new uses for hydrates (for example, energy recovery, separation, storage, and transportation of gas) prompting scientists to conduct new and more detailed studies of the hydrate formation process. Understanding the conditions and mechanisms of hydrate formation makes an engineer able to control this process. Therefore, in practice, simplified models are often required to predict hydrate formation. This paper presents various correlations that are widely used in the oil and gas industry to determine the temperature of hydrate formation. The accuracy of the presented models is compared. The influence of the features of the gas composition on the conditions for the hydrates formation is studied. It is shown that for the considered gases, the most accurate results can be obtained using the G.V. Ponomarev correlation. When the relative density of gases is greater than 0.6, it is possible to use the Towler and Bahadori correlations. Correlations proposed by Hammerschmidt, Mottie and Berge show the worst results. Since the temperature of hydrate formation in the considered correlations does not depend on the gas composition, but only on the relative density, the influence of the content of non-hydrocarbon components on the temperature of hydrate formation was studied in this work. It was found that the content of hydrogen sulfide has the greatest influence. Moreover, at high contents of hydrogen sulfide in the gas composition, the temperature of hydrate formation shifts towards higher values. The content of nitrogen and carbon dioxide to a lesser extent affect the value of the temperature of hydrate formation.