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“Hydrate-phobic” surface coatings to keep oil and gas pipes flowing

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April 11, 2012

'Hydrate-phobic' surface coatings could prevent blockages on deep-sea gas and oil wells (P...

'Hydrate-phobic' surface coatings could prevent blockages on deep-sea gas and oil wells (Photo: Shutterstock)

As the world’s appetite for oil and gas continues to increase while access to easily accessible reserves decreases, deep-sea oil and gas wells are being positioned in ever-deeper waters. The dangers and difficulties faced in such operations were highlighted in 2010 with the Deepwater Horizon oil spill. While placing a containment dome over a leak and piping the oil to a surface storage vessel had worked on leaks in shallower water, the attempt to do the same on the Deepwater Horizon’s largest leak failed when the formation of methane hydrate crystals blocked the opening at the top of the dome. Now researchers at MIT have developed surface coatings that can inhibit the buildup of these methane hydrates and keep the gas and oil flowing.

Methane hydrate is a solid cage-like compound – or clathrate – that forms under very high pressure in which a large amount of methane is trapped within a crystal structure of water to form an ice-like solid. Although it was originally thought to only occur in the outer reaches of the solar system, it is now estimated that total amount of methane contained in hydrates in the world’s seafloor is much greater than the total known reserves of all other fossil fuels combined.

Much like the buildup of grease on the inside of a kitchen drain or sewer, the buildup of methane hydrates - which can form when methane comes into contact with cold water in the depths of the ocean - inside a well casing or on the inner walls of pipes that carry oil or gas from the ocean depths can restrict or even block the flow of gas or oil. It was this kind of blocking that caused the failure of the containment dome technique attempt on the Deepwater Horizon leak.

Current techniques to prevent this happening include the heating or insulation of the pipes – which is expensive - or adding methanol into the flow of gas or oil – which can harm the environment if it escapes.

An MIT team led by associate professor of mechanical engineering Kripa Varanasi had been looking for a solution to this problem even before the Deepwater Horizon spill and now say they have found it. Having already studied the use of superhydrophobic surfaces to prevent the buildup of ordinary ice on things such as aircraft wings, the team decided to examine whether similar surfaces could be used to keep pipe walls clear of methane hydrates.

Using a simple “hydrate-phobic” coating, Varanasi and his colleagues were able to reduce the adhesion of hydrates in a pipe to one-quarter the amount compared to untreated surfaces.

“The oil and gas industries currently spend at least $200 million a year just on chemicals” to prevent methane hydrate buildups, Varanasi says. However, the total figure for prevention and lost production due to hydrates would be much, much higher. Using passive coatings on the insides of pipes would be much cheaper than current prevention techniques and allow the use of containment domes to capture flows from leaks in much deeper waters than is currently possible.

Additionally, the team says the test system they devised provides a simple and inexpensive way to search for even more effective inhibitors. They say their findings are also applicable to other adhesive solids, such as solder adhering to a circuit board, or calcite deposits inside plumbing lines. The testing methods developed by the researchers could also be used to evaluate coatings for a variety of commercial and industrial processes.

The team’s findings are detailed in a paper published in the journal Physical Chemistry Chemical Physics.

Source: MIT

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
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3 Comments

Relating the blockage of a pipeline by hydrates to the blocking of an artery by fatty deposits is an unfortunate comparison, as it is inaccurate, and perpetuates that medical myth.

Arteries do NOT block up because of elevated levels of 'cholesterol' (LDL, VLDL, or any other DL) or triglycerides flowing in our bloodstream, and randomly sticking to the artery walls. Arteries block up as the artery wall becomes inflamed and expands. As Cholesterol is the body's building and repair material, cholesterol-rich plaques accumulate WITHIN the artery wall, in an attempt to repair the damage. This additional cholesterol remains underneath the endothilium, which bulges out and constricts the artery. This occurs in specific locations, and does not necesarily affect the artery over a significant length, as hydrates can.

While practically both provide a flow restriction, the difference is non-trivial in terms of the implied casuation. Its the reason why artheriosclerosis is still highly prevelant - we have been misinformed as to what causes it, and the supposed solution. The low-fat diet, and targeting saturated fat as the 'baddie', is not helping the problem, its causing the problem. The problem is complex, and can include consumption of trans fat & industrially extracted polyunsaturated fat (vegetable oil in all its forms). These have replaced most natural animal fats & tropical fats in our diet, with disastrous health results. Targeting of 'cholesterol' using statin or other drugs is lining drug company pockets to the tune of Billions, and killing (or at very least, harming) us to boot. (refer to work by Dr Mary Enig & Dr Uffe Ravnskov).

Chronic stress has also been indicated as causing artheriosclerosis, due to elevated cortisol (see work by Dr Malcolm Kendrick).

Apologies for a medical rant on a technology website, but as you should see, the actual issue at stake is non-trivial, and I think, justifies it. Need to get the message out there.

BTW, I do know something about hydrates too, I'm in the industry.

Pipeliner
16th April, 2012 @ 03:56 am PDT

Good points Pipeliner. We've updated the article using the analogy of the buildup of grease on the inside of a kitchen drain or sewer as you suggested.

editor
16th April, 2012 @ 07:45 am PDT

Great reply Pipeliner, very informative.

I keep imagining teflon, i wonder if they are similar. Hey, both non-stick lol.

Calvin k
17th April, 2012 @ 07:01 am PDT
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