Hydrogel could green up fracking

Hydrogel could green up fracking

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A research team led by Carlos. Fernandez, at Pacific Northwest National Laboratory, US, created a hydraulic fluid that transforms into an expandable hydrogel on interacting with carbon dioxide and the expansion process produces enough force to fracture rock. The hydrogel could reduce the amount of water and chemical additives required for hydraulic fracturing used to generate underground reservoirs for geothermal energy production or for oil and natural gas extraction. They published their findings in the journal Green Chemistry. The team developed the process, which involved pumping an aqueous solution of polyallylamine into the ground followed by CO2. The CO2 interacted with the polymer’s amine groups and water to form a hydrogel that expands to more than twice its volume, creating pressure for fracking.Fernandez et al., tested the polyallylamine in rock cores in the lab and found that as well as expanding in seconds, the gelling process is completely reversible, through carbon dioxide depressurisation or the use of dilute acid. The new fluid would use only a fraction of the water typically required for fracking and it can be recovered and reused. It is stable at temperatures up to 400°C, making it suitable for use in enhanced geothermal systems (EGS). This switchable fluid builds on a range of green chemical systems developed over the past decade in which CO2 toggles the properties of solvents, surfactants, or catalysts back and forth to facilitate reactions and separations. In addition, the polymer has low toxicity and the amine groups function as a built-in biocide and corrosion inhibitor, which would reduce the number of additives normally included in fracking fluids.