Design of degradable hybrid dual-crosslinked polymer for high-efficiency profile control in high temperature reservoirs

Abstract

Profile control and water plugging are key technologies to enhance oil and gas recovery. Traditional plugging materials, due to short gelation time, low mechanical strength, and difficulty in balancing plugging and protection, thus limiting application in high temperature reservoirs. Herein, a degradable hybrid dual-crosslinked polymer was prepared by employing a copolymerization - dual-grafting and physical adsorption design strategy. The dual-crosslinked process and reaction mechanism were analyzed using infrared spectroscopy and differential scanning calorimetry. The mechanical properties, water dilution resistance, aging stability and degradability of the dual cross-linked composite were also investigated. The solvation forces enable silica particles to exhibit excellent suspension stability in a PEG solvent. The temperature ranges from normal atmospheric temperature (20 °C) to reservoir temperature (140 °C), with the apparent viscosity falling within the range of 10–1200 mPa·s, meeting the requirements for mixing and injection. The combination of free radical copolymerization and click reaction is utilized to control the gelation time (2–10 h) in high temperature environment (140 °C), which is favorable for regulating the action position of the plugging agent in the reservoir. The cured material exhibits excellent mechanical strength owing to the presence of dual-crosslinking and inorganic hybridization, with a compressive strength of 0.221 MPa and a peak strain of 55.3 %. Furthermore, this composite material undergoes hydrolysis through an addition-elimination reaction, transitioning from a solid to a liquid state within 24 h, thereby aiding in the restoration of productivity in the temporarily shielded target layer. Compared to traditional materials, this dual-crosslinked composite system have the advantages of controllable gelation time, high mechanical strength, aging resistance, and degradability, making it suitable for profile control in high temperature reservoirs (140 ℃, 21.81×104 mg/L).