Development of dual-crosslinked nanocomposite gel for water management in high-temperature reservoirs

Abstract

Due to their controllable gelation time and high gel strength, polymer gels are widely used in the oil and natural gas industry for sealing operations. Aiming at the problems of fast gelation time and poor stability of polymer gel when the temperature exceeds 120 °C, a dual-crosslinked nanocomposite gel for high-temperature reservoir water management was developed. Polymers, crosslinking agents, nanomaterials, and retarders were studied for the effects of the concentration of each component on the initial viscosity, gelation time, stability, and viscoelastic properties of the gel. The long-term stability and water-plugging adaptability were evaluated. FTIR and viscoelastic performance analyses clarified the mechanism of action. The gel strength and thermal stability enhancement mechanism was analyzed based on SEM. At 170 °C,the gelation time is 5 ∼ 10h after adding retarder and aging in formation water for 30 days resulted in dehydration rates within 10%. The injection volume of the plugging agent is 0.3 PV, and the plugging rate of sand-filled pipes with different permeability is above 97%. The elastic modulus of the terpolymer SAV333/phenol-formaldehyde system was increased by 10 times by resorcinol and SiO2. The enhancement mechanism is mainly due to the gel’s strong dendritic dual-crosslinked network structure and the dual role of hydrogen bonding and electrostatic attraction of SiO2. Dual-crosslinked nanocomposite gel (DCNG) has shown promising performance as sealing material in high-temperature and ultra-high-temperature reservoirs.