Geomimicry-Inspired Micro-Nano Concrete as Subsurface Hydraulic Barrier Materials: Learning from Shale Rocks as Best Geological Seals

Wellbore cement is the primary hydraulic barrier material used in wellbore construction, with properties similar to the formation rock. It serves multiple purposes such as providing mechanical support and zonal isolation, maintaining well performance, and restoring sealing barriers during the wellbore abandonment. However, Portland cement can have a brittle nature making it subject to mechanical failure at downhole conditions. To improve wellbore cement properties that impact it resistance to failure, three materials are explored as additives: (1) olivine to prevent chemical attack from CO₂-rich geofluids, (2) zeolite for its water storage and slow moisture release that can potentially prevent drying shrinkage, thus allowing secondary cement hydration and potentially promoting self-healing capabilities, and (3) graphene to increase strength and/or decrease tendency of the material to brittle fracture. Investigation of the mechanism for how each of these micro-nano aggregates contributes to the enhanced performance of the cement matrix indicates that all can have positive impact on cement properties that enable effective and resilient zonal isolation.