Two-phase heat transfer modeling in subsea pipelines

Abstract

Rising global energy demand has led to new operational challenges in unfamiliar environments, with higher temperature gradients. The challenges directly address safety, environmental and economic issues. Due to the low subsea temperatures and relatively higher petroleum fluid temperature in deep water pipelines, convectional heat losses occur from the petroleum fluids to the surroundings. This heat transfer is necessary to be considered, to ensure the proper flow of petroleum fluids. While conventional equivalent heat transfer models are easier to compute, they are not accurate enough to reflect the changes that would occur within a fluid due to different multiphase flow regimes and proportions. The objective of this paper is to develop a low dimensional and low computational equivalent thermal model of subsea fluids, which can predict two-phase fluid temperatures along insulated subsea pipelines. The developed heat transfer model combines the application of two-phase heat transfer coefficient model with fluid properties obtained from a low dimensional fluid model developed by our group. The presented model shows the effect of heat transfer in subsea pipelines for two-phase fluids for normal operating and shut-down conditions. This model, when compared with industry standard software, showed that results were obtained with similar accuracy with approximately 1000 times less computational time.