Objective In order to solve the problem that traditional polymer water plugging gel is difficult to adapt to high temperature and high salt environment, a temperature and salt-resistant water-plugging gel is prepared from phenylpropane lignin by amination modification and crosslinking curing.

Method The effects of amination modification degree of lignin, amount of crosslinking agent, the content of lignin amine and curing temperature on the physical strength of the gel were investigated; the aging-resistance of lignin amine water-plugging gel was evaluated, and the water-plugging application experiment was carried out in the field.

Result  The results showed that when the mass ratio of lignin to amine was 1∶2, the dosage of polyethylene glycol diglycidyl ether (PEGDGE) was 20 wt%, content of lignin amine was 15 wt% and the temperature was 150 ℃, the curing time was 5 h; the compression stress of cured gel block was 597 kPa after aging for 90 days with 210×10³ mg/L mineralized salt water, and the volume retention rate of gel was 89.7%. The on-site application results showed that when the lignin amine water-plugging system with optimal ratio was injected into the formation environment with 140 ℃ and 210×10³ mg/L mineralization, the water content of the oil recovery decreased from 99.0% before injection to 58.5% after injection, and the maximum daily crude oil production was 13.8 t. The adequate action time could reach 90 days.

Conclusion As a waste material, lignin has potential application prospects in high-temperature and high-salt oil fields after modification.