Disulfide‐Bond Self‐Healing Polymer as Wellbore‐Stabilizing Agent for Water‐Based Drilling Fluids

Wellbore instability is a critical challenge in oil and gas drilling. Conventional LCMs adopt physical sealing with poor bonding efficiency, which restricts their wellbore strengthening performance. A novel self‐healing CKGB based on reversible covalent disulfide bonds was developed for drilling fluid wellbore stability enhancement. FT‐IR spectroscopy, DSC, and in situ FT‐IR spectroscopy verified its successful synthesis, thermal stability and dynamic reversible disulfide bond exchange (bulk bonding efficiency 75%, heat resistance up to 120°C). CKGB enhanced rock mechanical properties, increasing compressive strength of sandstone and shale by 395.3%/71.7%, respectively, and the rock cementation strength by 809.1%. CKGB also inhibited hydration swelling and maintained good performance under high temperature and high salinity. Drilling fluids modified with CKGB achieved a ≥ 68% reduction in HTHP fluid loss at 120°C–160°C, and low sand‐bed filtration and micro‐fracture leakage; SEM and EDS confirmed the formation of a dense pressure‐bearing sealing layer in pores and fractures, providing an effective solution for wellbore‐stability enhancement in unstable formations.