Poly(N-acryloyl glycine) based temperature/pH-responsive hydrogels reinforced with montmorillonite for plugging of damaged oil pipeline

Hydrogel as a temporary plugging material provides an efficient strategy to replace locally damaged oil pipelines. However, the poor mechanical properties and incomplete gel-breaking severely limit the practical application of this strategy. Herein, a temperature and pH-responsive hydrogel P(ACG-co-AM)-MMT was prepared by copolymerizing a natural amino acid derivative monomer N-acryloyl glycine (ACG) and acrylamide (AM) with montmorillonite (MMT) as filling material. Hydrogen bonding is the main driving force in hydrogel formation, as confirmed by infrared spectroscopy. The introduction of MMT plays a key role in enhancing the mechanical properties of hydrogels. This successfully overcame the issues of inadequate mechanical properties-rapid degradation trade-off in hydrogel temporary plugging materials. The results show that the hydrogel can withstand the pipeline pressure up to 84 kPa and effectively plug the pipeline. Due to the reversibility of hydrogen bonds, the hydrogel can realize the transformation of sol-gel-sol under temperature stimulation. The plugged area of the pipeline is removed by injecting thermal-produced water. When the hot water temperature is 85 ℃, the pipeline changes to the dredging state only 21 min, dramatically simplifying the operation time. P(ACG-co-AM)-MMT hydrogel has great potential as a temporary plugging material in replacing partially damaged oil pipeline plugging operations.