British Columbia University (UBC) researchers have proposed a new technique for improving the transportation of heavy oils.
According to the researchers, their new Viscoplastic Lubrication (VPL) technique helps stabilize the interface of multilayer flows for transportation.
During the past 20 years, the oil industry has been gradually transitioning away from light oils toward heavier oils.
Transporting heavy oils cost-effectively however remains a big challenge because they are viscous, which makes them a thick, sticky and semifluid mess.
Stabilizing the interface of multilayer flows for transportation is no easy task.
While several potential solutions have been proposed, no one-size-fits-all approach currently exists that works for all applications.
The UBC team is hoping to remedy that by focusing on multilayer flows – with special emphasis on lubricated pipeline flow.
In lubricated pipeline flow, a thin fluid, such as water, is used to lubricate the pipeline via core-annular flows.
This method however suffers from interfacial instabilities, which means the oil and water may mix and make it more difficult to separate downstream.
According to UBC professor Ian Frigaard, in multilayer flows, the interfaces between two fluids are highly unstable because of the differences between fluid properties.
Previous work by the researchers on yield stress fluids suggested a new configuration might prevent instabilities from growing.
Their VPL technique for instance places a layer of yield stress fluid between the heavy oil and the lubricant to form a flow stabilizing skin.
“Yield stress fluids – think toothpaste or hair gels – act as a solid if the applied stress is less than its yield stress,” notes Parisa Sarmadi, a doctoral candidate working with Frigaard.
“Our idea is to maintain this layer completely unyielded, so the interfacial layer of the fluid acts as a solid. This eliminates interfacial instabilities.”
Their study also focuses on interface shaping: “We can control the inlet flow rates in a way to shape the interface as we desire,” says Sarmadi.
“The shaped interface generates pressure within the outer layer, and these pressures act to counterbalance the core buoyancy to center the core fluid. Typically, the transported oil is less dense than the lubricating water.”
According to the researchers, the VPL technique can be optimized based on pump power, generated force and required yield stress.
Image and content: Getty Images via ExpressUK/University of British Columbia