Oil‐Absorbing Swelling Pellet P( MMA ‐ AM ‐ DVB ) for Enhancing the Sealing Performance and Wall Stability of Oil‐Based Drilling Fluids

ABSTRACT To achieve efficient plugging in oil‐based drilling fluid and enhance wellbore stability, P(MMA‐AM‐DVB) oil‐absorbing expandable particles with excellent oil absorption and high‐temperature resistance were prepared. Methyl methacrylate (MMA) and acrylamide (AM) served as monomers, and divinylbenzene (DVB) as a crosslinking agent, with the optimal formula obtained via molecular structure design. The particles were characterized using FTIR, SEM, TGA‐DSC, contact angle analysis, oil absorption tests, and drilling fluid performance evaluation. The results demonstrated the successful synthesis of P(MMA‐AM‐DVB) with a well‐defined three‐dimensional network structure. The thermal decomposition temperature of P(MMA‐AM‐DVB) was as high as 500°C, indicating excellent thermal stability, and the contact angle between the particles and water was greater than 85°. Oil absorption stabilized within 10 min (with an oil absorption rate > 4.5 g/g) with increased particle size after absorption, demonstrating significant stability and excellent oil absorption capacity. The particles had little impact on the rheology of oil‐based drilling fluid at different aging temperatures; they were able to complete oil absorption, expansion, deformation, and compaction within 30 min before entering formation fractures, thereby achieving effective plugging, thus realizing efficient plugging and supporting wellbore stability.