Microwaved nanoribbons strengthen oil and gas wells

Rice University researchers have developed a method to treat composite materials of graphene nanoribbons and thermoset polymers with microwaves in a way that could dramatically reinforce wellbores for oil and gas production
According to researchers from Rice University, wellbores drilled to extract oil and gas can be dramatically reinforced with a small amount of modified graphene nanoribbons added to a polymer and microwaved.

Chemist James Tour and civil and environmental engineer Rouzbeh Shahsavari combined the nanoribbons with an oil-based thermoset polymer intended to make wells more stable and cut production costs. When cured in place with low-power microwaves emanating from the drill assembly, the composite plugs the microscopic fractures that allow drilling fluid to seep through and destabilise the walls.

The researchers said that in the past, drillers have tried to plug fractures with mica, calcium carbonate, gilsonite and asphalt to little effect as the particles are too large and the method is not efficient enough to stabilise the wellbore.

In lab tests, a polymer-nanoribbon mixture was placed on a sandstone block, similar to the rock that is encountered in many wells. The team found that rapidly heating the graphene nanoribbons to more than 200°C with a 30W microwave was enough to cause crosslinking in the polymer that had infiltrated the sandstone.

"This is a far more practical and cost-effective way to increase the stability of a well over a long period," Tour said.

In the lab, the nanoribbons were modified with polypropylene oxide to aid their dispersal in the polymer. Mechanical tests on composite-reinforced sandstone showed the process increased its average strength from 5.8 to 13.3megapascals, a 130% boost in this measurement of internal pressure.

"That indicates the composite can absorb about six times more energy before failure," Shahsavari said. "Mechanical testing at smaller scales via nanoindentation exhibited even more local enhancement, mainly due to the strong interaction between nanoribbons and the polymer. This, combined with the filling effect of the nanoribbon-polymer into the pore spaces of the sandstone, led to the observed enhancements."

Author
Tom Austin-Morgan

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