Nav: Home

Researchers design coatings to prevent pipeline clogging

April 14, 2017

CAMBRIDGE, Mass. -- When the Deepwater Horizon oil rig suffered a catastrophic explosion and blowout on April 21, 2010, leading to the worst oil spill in the history of the petroleum industry, the well's operators thought they would be able to block the leak within a few weeks. On May 9 they succeeded in lowering a 125-ton containment dome over the broken wellhead. If that measure had worked, it would have funneled the leaking oil into a pipe that carried it to a tanker ship above, thus preventing the ongoing leakage that made the spill so devastating. Why didn't the containment work as expected?

The culprit was an icy mixture of frozen water and methane, called a methane clathrate. Because of the low temperatures and high pressure near the seafloor, the slushy mix built up inside the containment dome and blocked the outlet pipe, preventing it from redirecting the flow. If it hadn't been for that methane clathrate, the containment might have worked, and four months of unabated leakage and widespread ecological devastation might have been prevented.

Now, a team of researchers at MIT has come up with a solution that might prevent such a disastrous outcome the next time such a leak occurs. It may also prevent blockages inside oil and gas pipelines that can lead to expensive shutdowns to clear a pipe, or worse, to pipeline rupture from a buildup of pressure.

The new method of preventing the icy buildup is described in a paper in the journal ACS Applied Materials and Interfaces, in a paper by associate professor of mechanical engineering Kripa Varanasi, postdoc Arindam Das, and recent graduates Taylor Farnham SB '14 SM '16 and Srinivas Bengaluru Subramanyam PhD '16.

The key to the new system is coating the inside of the pipe with a layer of a material that promotes spreading of a water-barrier layer along the pipe's inner surface. This barrier layer, the team found, can effectively prevent the adhesion of any ice particles or water droplets to the wall and thus thwart the buildup of clathrates that could slow or block the flow.

Unlike previous methods, such as heating of the pipe walls, depressurization, or using chemical additives, which can be expensive and potentially polluting, the new method is completely passive -- that is, once in place it requires no further addition of energy or material. The coated surface attracts liquid hydrocarbons that are already present in the flowing petroleum, creating a thin surface layer that naturally repels water. This prevents the ices from ever attaching to the wall in the first place.

Existing prevention measures, known as flow assurance measures, "are expensive or environmentally unfriendly," says Varanasi, and currently the use of those measures "runs into the hundreds of millions of dollars" every year. Without those measures, hydrates can build up so that they reduce the flow rate, which can reduce revenues, and if they create blockages then that "can lead to catastrophic failure," Varanasi says. "It's a major problem for the industry, for both safety and reliability."

The problem could become even greater, says Das, the paper's lead author, because methane hydrates themselves, which are abundant in many locations such as continental shelves, are seen as a huge new potential fuel source, if methods can be devised to extract them. "The reserves themselves substantially overshadow all known reserves [of oil and natural gas] on land and in deep water," he says.

But such deposits would be even more vulnerable to freezing and plug formation than existing oil and gas wells. Preventing these icy buildups depends critically on stopping the very first particles of clathrate from adhering to the pipe: "Once they attach, they attract other particles" of clathrate, and the buildup takes off rapidly, says Farnham. "We wanted to see how we could minimize the initial adhesion on the pipe walls."

The approach is similar to that being used in a company Varanasi established to commercialize earlier work from his lab, which creates coatings for containers that prevent the contents -- anything from ketchup or honey to paint and agrochemicals -- from sticking to the container walls. That system involves two steps: first creating a textured coating on the container walls, and then adding a lubricant that gets trapped by the texture and prevents contents from adhering.

The new pipeline system is similar to that, Varanasi explains, but in this case "we are using the liquid that's in the environment itself," rather than applying a lubricant to the surface. The key characteristic in clathrate formation is the presence of water, he says, so as long as the water can be kept away from the pipe wall, clathrate buildup can be stopped. And the liquid hydrocarbons present in the petroleum, as long as they cling to the wall thanks to a chemical affinity of the surface coating, can effectively keep that water away.

"If the oil [in the pipeline] is made to spread more readily on the surface, then it forms a barrier film between the water and the wall," Varanasi says. In lab tests, which used a proxy chemical for the methane because the actual methane clathrates form under high-pressure conditions that are hard to reproduce in the lab, the system performed very effectively, the team says. "We didn't see any hydrates adhering to the substrates," Varanasi says.
-end-
The research was funded by the Italian energy company Eni S.p.A. through the MIT Energy Initiative.

ADDITIONAL BACKGROUND:

ARCHIVE: Kripa Varanasi: Innovating at interfaces http://news.mit.edu/2017/faculty-profile-kripa-varanasi-0119

ARCHIVE: Reducing runoff pollution by making spray droplets less bouncy http://news.mit.edu/2016/reducing-runoff-pollution-making-spray-droplets-less-bouncy-0830

ARCHIVE: LiquiGlide slides into consumer space http://news.mit.edu/2015/liquiglide-condiments-0630

Massachusetts Institute of Technology

Related Methane Articles:

Microbial fuel cell converts methane to electricity
Transporting methane from gas wellheads to market provides multiple opportunities for this greenhouse gas to leak into the atmosphere.
Methane seeps in the Canadian high Arctic
Cretaceous climate warming led to a significant methane release from the seafloor, indicating potential for similar destabilization of gas hydrates under modern global warming.
Methane emissions from trees
A new study from the University of Delaware is one of the first in the world to show that tree trunks in upland forests actually emit methane rather than store it, representing a new, previously unaccounted source of this powerful greenhouse gas.
Oil production releases more methane than previously thought
Emissions of methane and ethane from oil production have been substantially higher than previously estimated, particularly before 2005.
Bursts of methane may have warmed early Mars
The presence of water on ancient Mars is a paradox.
More Methane News and Methane Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.