Luteolin-bisphenol A epoxy double-walled self-healing microcapsules: Preparation and performance for deep formation wellbore stabilization in water-based drilling fluids

Deep hydrocarbon resources are recognized as a critical replacement domain for global oil and gas reserves. However, wellbore instability during the application of water-based drilling fluids represents a critical risk for cores, which severely constrains drilling efficiency and operational safety. Herein, a double-walled self-healing microparticles (MPSD) encapsulating epoxy monomer of bisphenol A and luteolin diglycidyl ether composite (BL-DGE) for wellbore stabilization was innovatively proposed and developed. MPSD exhibited a regular spherical morphology with a compact, dense surface, coupled with excellent thermal resistance and mechanical performance. After being immersed in an aqueous environment at 160–200 °C for 16 h, the shale slices treated with MPSD exhibit a shear strength of 634–707 kPa. Furthermore, under high-temperature immersion conditions, the shale cuttings are bonded into an integral structure by MPSD. The permeability of the artificial core treated with MPSD was reduced from 0.95 to 0.162 mD, with a plugging rate of 82.95%. The shell of the microparticles fracture under high-temperature conditions, releasing BL-DGE. By plugging the pores of the rock debris, the loose and fragmented rock is bonded into a dense and stable monolithic structure, significantly improving its mechanical properties and stability. This work provides an important theoretical foundation and technical solution for wellbore stabilization using water-based drilling fluids in deep fractured formations.