부산대학교 도서관

During cementing construction, H2S gas leak from micro-cracks of cement ring or cementing interface,seriously damaging wellbore integrity and shortening the life of wells. Therefore, microcrack selfhealingcement technology is of great significance for oil wells to maintain the durability of cement ringsand adapt to complex underground environments. Herein, acrylamide (AM), acrylonitrile (AN) and Nvinylformamide(NVF) were used as functional monomers, and laponite was added to prepareLaponite-poly(acrylamide-acrylonitrile-n-vinylformamide) nanocomposite hydrogel (L-PMAN) withexcellent mechanical strength as micro-crack repair agent for gas-triggered cementing cement sheath. Considering the difference of chemical environment in the process of wellbore cement slurry sealingand subsequent micro-fracture plugging, different structural units were selected to design amphotericstructure. The construction of zwitterionic structure makes it exhibit excellent swelling behavior in saltsolution while maintaining 80% of the original mechanical strength. More importantly, after adding LPMANpowder,cement stone (C1) can achieve good repair of microcracks under the trigger of H2S within3 days, and the maximum gas breakthrough pressure can reach 2.5 MPa, indicating the great potentials ofthe L-PMAN for plugging microcracks in cement sheath.