Can bismuth prevent oil leaks and save Norwegians billions?

Over the following 25 years, because the world shifts away from fossil fuels, the oil and gasoline wells which have sustained the fossil gasoline age should be plugged.

No huge deal, you may assume, drilling these wells was the onerous half. Plugging them must be no downside. However assume once more.

The Norwegian Continental Shelf, for instance, is punctured by greater than 2,000 wells. Harald Linga, heart director for SWIPA, a Middle for Analysis Based mostly Innovation based mostly at SINTEF, Scandinavia’s largest impartial analysis institute, estimates that plugging them utilizing right this moment’s know-how will price upwards of NOK 800 billion—that is USD 73 billion.

And whereas oil companies are answerable for plugging the wells, Norwegian taxpayers should shoulder 78% of those prices.

And that is simply Norway. The entire variety of oil wells throughout the globe may quantity within the tens of millions, all of which at a while should be plugged.

A seek for options

Right now’s know-how entails utilizing a cement plug that may be between 50–100 meters lengthy. These plugs, it seems, aren’t that nice. They will develop leaks over the long term, for a lot of completely different causes, says Lewaa Hmadeh, a Ph.D. candidate on the Norwegian College of Science and Expertise (NTNU’s) Division of Geoscience and Petroleum who can also be affiliated with SWIPA. One of the troubling issues is that leaking deserted petroleum wells is usually a important supply of greenhouse gasoline emissions, he stated.

“Every year, the Norwegian Oil and Gas Association sets a roadmap for new plugging and abandonment technologies needed to solve problems faced by the industry, and ever since 2015, finding an alternative to cement has always been there,” Hmadeh stated.

However there’s hope in sight.

Hmadeh’s Ph.D. analysis entails learning using bismuth instead and/or additive for plugging wells. He is one among many scientists throughout the globe looking for a greater answer for this problem. And if his preliminary outcomes are any indication, a mixture of bismuth and tin may provide the petroleum trade a safer and cheaper answer to properly plugging than cement.

The issue

To start with, it is necessary to keep in mind that plugging an oil properly is an expense that’s simply that—by definition, it is achieved on the finish of the lifetime of the properly, so it’s a price for which there isn’t any revenue.

“There’s no revenue,” Hmadeh stated. “You are literally burying the money there in the ground.”

Cement has change into the trade normal, partly as a result of the substance itself is comparatively low-cost, and its properties are well-known. However over time, the issues with a cement plug—which underneath Norwegian laws, must be between 50–100 meters lengthy—have come clear, Hmadeh stated.

“They are highly vulnerable to corrosion,” and to CO₂or hydrogen sulfide, each of that are present in subsea properly environments, he stated. The plugs even have to face up to large variations in strain above the plug and under.

They will crack or lose their seal within the high pressureexcessive temperature environments which might be typical of wells. And maybe most significantly, cement additionally shrinks because it cures, which causes the formation of little pores.

“These can be paths for hydrocarbons to migrate to the surface,” Hmadeh stated.

The trade has experimented with completely different options, various from including substances to cement and testing different substances, together with bismuth. That is the place Hmadeh’s work is available in.

Why bismuth?

Bismuth alloys are impermeable, which suggests there isn’t any probability for there to be leaks by means of the plug, Hmadeh says.

And in contrast to cement, which shrinks because it solidifies, bismuth alloys increase as they solidify.

“They also maintain their integrity over the long term, because they are not affected by corrosion, or by CO₂ or hydrogen sulfide. And they also have a reduced installation time due to the rapid hardening of the alloy,” Hmadeh stated.

This final might be an necessary issue on the Norwegian Continental Shelf, the place sea situations might be difficult, and the much less time wanted to put in the plug, the higher, he stated.

“Reduced installation time reduces the rig time, which in turn reduces costs,” Hmadeh stated. “One other aspect of bismuth alloy plugs is that they have the potential to be deployed riglessly, meaning that without the necessity of having a rig in place. This will in turn cut on costs drastically, as most of the costs offshore come from the ‘rig-rental’ costs.”

Within the lab

Hmadeh’s laboratory experiments have in contrast the efficiency of bismuth alloys to cement plugs. In a single examine, he performed a leak check in metal pipes, akin to an oil properly, with a 185 mm cement plug and a 121 mm bismuth-tin alloy plug.

When Hmadeh performed hydraulic “push-out” assessments and leakage assessments with nitrogen gasoline, he discovered that bismuth alloy plugs had larger resistance to utilized strain and diminished gasoline migration in comparison with cementwhich meant the bismuth alloy makes a greater seal.

However Hmadeh cautions that it is a great distance from the lab bench to precise wellbores, a lot extra work is required.

“Our team at NTNU is doing a great job making extensive knowledge about this new technology public and accessible for everyone,” he stated. “It is too early to attract conclusions. However this plug has nice potential. We have now to upscale it to see the way it will behave at completely different lengths,” which can take some years.