Compound and Efficient Blockage-Removal Agent for Polymer Flooding Oilfield

Aiming at the problem of complex blockages in which polymers, inorganic scales and heavy oils are wrapped around each other after long-term polymer injection in the polymer flooding oilfield, resulting in serious blockage of the formation, a stable and efficient compound blockage-removal agent with 0.6% percarbonamide, 1% acetic acid, 0.3% OP-10, 1%DTPMP, and 1%HSJ-3 was prepared. And the properties of the compound blockage-removal agent were evaluated. The results showed that the agent can effectively degrade the simulated blockages under different temperature conditions. Under the condition of 80 ℃, the degradation rate of more than 90% can be reached in 4 h, with excellent degradation performance and temperature resistance. Placed at 80 ℃ for 1 h, the stability was maintained at 97%, with good stability performance and the corrosion rate was 0.9871 g·m⁻²·h⁻¹, which met the industry-level standard. When prepared with 15×10⁴ mg/L high salinity brine, the blockage-removal efficiency was basically not affected and the salinity resistance is excellent. The compound blockage removal agent can effectively solve the complex blockages formed in the process of polymer flooding through gradual stripping and continuous degradation. After injecting the composite blockage-removal agent, the core permeability increased from 0.244×10⁻³ μm² to 6.391×10⁻³ μm², and the permeability increased by a factor of 25.192. The compound block-removal agent can effectively solve the complex blockages.