Effect of Two–Phase Flow on Gas Permeability in Marine Flexible Pipelines

Abstract

The flexible composite pipes are quite suitable for the development of marine oil&gas reservoirs due to the excellent characteristics of design abilities, economics and dynamic behaviors. At present, the theories and methods of the gas permeations in the composite walls have not yet considered the influences of the multiphase flow in the inner pipes. Therefore, the prediction accuracies of the permeation rates are expected to improve for the marine flexible pipelines with significant differences of pressure and temperature drops. In this paper, a comprehensive gas permeation model including gas-liquid two-phase flow is proposed, and the effect of flow patterns on the gas permeation rate and vent period is investigated numerically. The results show that the flow patterns of multi-phase flow have significant impact on the permeation rate of gas due to different pressure drop and temperature drop for the same mass flow rate, and the permeation rate of CO2 is higher than that of CH4 under the same working condition.