This graphic shows how wellbores drilled to extract oil and gas can be reinforced with a mixture of graphene nanoribbons and a thermoset polymer. Image: Nam Dong Kim/Rice University.Wellbores drilled to extract oil and gas can be dramatically reinforced with a material produced by adding a small amount of modified graphene nanoribbons to a polymer and microwaving it, say researchers from Rice University.
The Rice labs of 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 to cut production costs. When cured in place with low-power microwaves emanating from the drill assembly, the composite could plug the microscopic fractures that can allow drilling fluid to seep through and destabilize the walls of the well. The results of this study are reported in a paper in ACS Applied Materials and Interfaces.
According to the researchers, drillers have in the past tried to plug fractures with various different materials, including mica, calcium carbonate, gilsonite and asphalt, but to little avail because the particles are too large and the method is not efficient enough to stabilize the wellbore.
When the researchers placed a solution of the polymer and nanoribbon on a sandstone block, similar to the rock encountered in many wells, it quickly soaked into the block through any cracks. The team then found that rapidly heating the graphene nanoribbons to more than 200°C with a 30-watt microwave caused crosslinking in the polymer that had infiltrated the sandstone. The microwave energy needed is just a fraction of that typically used by a kitchen appliance, Tour said.
"This is a far more practical and cost-effective way to increase the stability of a well over a long period," he added.
The nanoribbons were functionalized – or modified – with polypropylene oxide to aid their dispersal in the polymer. Mechanical tests on sandstone reinforced with the polymer-nanoribbon mixture showed the process increased its average strength from 5.8 megapascals to 13.3 megapascals. Similarly, the toughness of the reinforced sandstone increased by a factor of six.
"That indicates the composite can absorb about six times more energy before failure," Tour 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."
The researchers suggest that a low-power microwave attachment on the drill head would allow for in-well curing of the nanoribbon-polymer solution.
This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.