Correlation for calculating frictional pressure drops in vertical three-phase flows for subsea-resource production

Subsea minerals and methane hydrate are found in deep seas within the exclusive economic zone of Japan. However, they have not been commercialized owing to some technical issues. Gas-lift pumping is a promising technique for transporting subsea minerals and methane hydrate from the seafloor to the sea surface. Nevertheless, methods for calculating frictional pressure drops in three-phase flows need to be established because internal flows in pipes become three-phase flows in gas-lift pumping systems. To establish such methods, we reviewed existing correlations for calculating frictional pressure drops in two-and three-phase flows. Next, we conducted an experiment on gas-liquid two-phase and gas-liquid-solid three-phase flows through transparent polyvinyl chloride pipes using resin balls as solid particles. Subsequently, we compared the calculated results with the experimental data. We modified the correlations that showed good performance in the comparison for three-phase flows and proposed new correlations for calculating frictional pressure drops in vertical three-phase flows. Further, we compared the calculated results based on the modified and new correlations with the experimental data for a three-phase flow to evaluate the correlations. The new correlation could be used to calculate frictional drops in three-phase flows more accurately than the other correlations. In addition, the new correlation could be used to calculate a wider range of pressure drops than the other correlations because it contains no experimental constant. Thus, the proposed correlation is more accurate and effective for calculating frictional pressure drops in vertical two-and three-phase flows than other correlations.

Automated summary

Subsea minerals and methane hydrate have been found in the exclusive economic zone of Japan, but commercialization has been hindered by technical issues. Gas-lift pumping is a promising technique for transporting these resources, but accurate methods for calculating frictional pressure drops in three-phase flows are needed. This study reviewed existing correlations and conducted experiments to propose new correlations for calculating frictional pressure drops in vertical three-phase flows.