Novel Resin–Gel Composite for Multistage Water Shut‐Off in Fractured Tight Reservoirs: Mechanistic Insights and Performance Evaluation

The development of fractured tight oil reservoirs is challenged by early water breakthrough and inefficient sweep efficiency. This study presents a novel resin–gel composite (composed of thermosetting phenolic resin, xanthan gum, bentonite, and sodium metasilicate) for multistage conformance control. The composite forms through a three‐stage mechanism: (1) dispersion at room temperature (involving xanthan hydration and bentonite charge neutralization), (2) dual cross‐linking at 70°C (via silanization‐derived Si–O–C covalent bonds and Na + ‐mediated “bentonite–xanthan” ionic bridges), and (3) three‐dimensional curing through resin self‐condensation. With an optimized xanthan gum concentration of 0.2 wt%, the composite exhibits injectable viscosity (68.57 mPa s) and rapid curing (curing time decreases from 56 to 16 h as temperature increases from 50°C to 90°C). Physical simulations demonstrate outstanding plugging strength (24.32 MPa m −1 in 0.5‐mm capillaries) and preferential migration into large fractures, enabling sequential fracture blocking. Fractured core flooding experiments confirm an incremental oil recovery of 12.56% through two‐stage treatments, validating the composite's effectiveness in fractured reservoirs.