Study Is First to Examine How Oil and Gas Tumbling Inside Pipe Affects Released Oil Estimations
October 17, 2018
Scientists analyzed visual observations and computer simulations of the Deepwater Horizon oil flow to better understand the characteristics of an uncontrolled pipeline flow and how they affect the amount of oil discharge and droplet size distribution, which are critical for effective response decisions. The study suggests that spill’s plume was likely not from a bubbly flow but rather from a more dynamic churn where oil and gas tumble within the pipe. Compared with a bubbly flow, a churn flow could potentially produce five times the energy loss in the pipe, and its plume could entrain 35% more water. Not accounting for this larger energy dissipation caused by a churn flow could result in an overestimation of discharged oil, perhaps by more than 200%. The significant implications of churn versus bubbly flow demonstrates the need to evaluate both types when assessing subsea blowouts.
The researchers published their findings in Geophysical Research Letters: Was the Deepwater Horizon well discharge churn flow? Implications on the estimation of the oil discharge and droplet size distribution.
The petroleum industry pumps crude oil out of below-seafloor geological reservoirs through pipelines so that it can ultimately be refined for end users. A controlled pipeline flow can range from streamlined to stratified to turbulent. Complicating the oil flow is its multiphase nature, where gas, additives, methane hydrates, and other gases and condensates can also be transported. During Deepwater Horizon, various groups implemented formidable efforts to estimate the oil flow rate, and all but one estimate assumed a bubbly flow. However, the video of oil coming out from the riser (provided by the Natural Resource Damage Assessment) suggested a behavior closer to churn, which has a more dynamic flow with significantly different hydrodynamics than a bubbly flow.