Abstract
Improved understanding of the character of an uncontrolled pipeline flow is critical for the estimation of the oil discharge and droplet size distribution both essential for evaluating oil spill impact. Measured oil and gas properties at the wellhead of the Macondo255 and detailed numerical modeling suggested that the flow within the pipe could have been “churn,” whereby oil and gas tumble violently within the pipe and is different from the bubbly flow commonly assumed for that release. The churn flow would have produced 5 times the energy loss in the pipe compared to bubbly flow, and its plume would have entrained 35% more water than that of the bubbly flow. Both findings suggest that the oil discharge in Deepwater Horizon could have been overestimated, by up to 200%. The resulting oil droplet size distribution of churn flow is likely smaller than that of bubbly flow.
Key Points
Existing studies of the DWH assumed bubbly flow in the well riser; we showed that the flow might have been churn, where oil and gas tumble within the pipe
Churn flow results in much larger energy dissipation, and if presented and neglected, could cause one to overestimate the oil discharge
Churn flow results in a smaller oil droplet size distribution and could impact applied dispersant effectiveness
