Application of crosslinked gel and cement slurry composite leak-sealing technology in deep salt mines

Abstract:

During the exploration and development of deep salt mineral resources， the frequent technical challenge of drilling fluid loss is characterized by complex formation mechanisms and significant sealing difficulties. Under the combined effects of tectonic stress， groundwater dissolution， and engineering disturbances， reservoirs and near-wellbore zones are prone to developing multi-scale fracture networks and even dissolution cavities， forming a multi-channel seepage system. A case in point is Well A from a brine extraction project in Hebei Province： leakage occurred at a depth of 2594m， which evolved into a total loss scenario with simultaneous influx and leakage in the same stratum at 2598m， severely impacting drilling efficiency. To address this leakage issue， this study employs crosslinked gel and cement slurry composite sealing technology. Leveraging the excellent water plugging capabilities and controllable crosslinking time of the gel， a network-like separation layer was formed to provide effective support for subsequent cement slurry consolidation. After two sealing operations， the drilling fluid return reached approximately 80% of the normal flow rate. This composite technology effectively overcomes the adaptability limitations of traditional single sealing materials and offers a novel solution for managing severe leakage in deep drilling engineering.