Interwell channeling and sealing technology in Changqing CCUS block

Abstract In the Changqing Oilfield’s CCUS (Carbon Capture, Utilization, and Storage) project, a novel fracture-based inter-well gas migration sealing technology was developed to address the challenges of reduced production and even shutdown of oil and water wells due to inter-well migration. This was particularly crucial in the context of low fracture pressure-bearing capacity below 40 MPa, the absence of precedents in inter-well gas migration sealing techniques, and the difficulty in accurately estimating the fracture communication volume. The technology is grounded in multi-segment plug water blocking techniques, utilizing geological and well-network data to simulate the gas volume within fractures, thereby determining the precise quantity of plugging agent required. To meet the long-term sealing needs, the technology not only incorporates corrosion-resistant gel in the multi-segment plugs but also integrates water-dispersive cement slurry and CO 2 corrosion-resistant cement slurry to enhance the durability of the seal. The injection parameters were optimized based on the pressure-bearing characteristics of the formation to prevent pressure leakage. Field tests indicated that the injection pressure increased by 4 MPa after the application of this technology. Despite the occurrence of gas migration during the plugging process, the close approximation between the designed injection volume of 350 cubic meters and the actual required volume of 326 cubic meters suggests that the technique could achieve its intended effectiveness with further adjustments. This technology provides new insights for handling similar inter-well migration issues in CCUS projects and serves as a reference for other similar endeavors.