Fundamental Studies on Fluids-Independent Regenerative Nanocomposite Hydrogels for Fracture Treatments of Conformance Control.

Abstract

Traditional granular hydrogels showed excellent injectivity, thermal integrity, and efficient remediation of heterogeneous reservoirs. However, granular hydrogels have demonstrated their inability to adapt to fractures due to the lack of sufficient interactions. Herein, we present new nanocomposite hydrogels consisting of cationic nanogelators and anionic granular hydrogels that can chemically in situ reform bulk hydrogels in the fractures. Interestingly, our granular hydrogels showed recross-linking independence on carrying fluids, contrary to prior reported fluid-dependent recross-linking granular hydrogels. The recross-linking of nanogelators and granular hydrogels can be accomplished from room temperature to 130 °C. The nanocomposite hydrogels displayed increased shear elastic moduli compared to pristine anionic granular hydrogels, probably due to the increased covalent cross-links formed by the homogeneous regenerative approach. We found that the granular hydrogels had high salinity tolerance even in the presence of 1000 ppm divalent ions of calcium (Ca2+) since Ca2+ ions often act as the cross-linker for partially hydrolyzed acrylamide-based hydrogels. Overall, we obtained new regenerative nanocomposite hydrogels based on cationic nanogelators and anionic granular hydrogels for fracture treatments.