Study on a heat resistant and salts tolerant instant gel plugging agent suitable for offshore oilfield

In view of the problems of long dissolution time, poor stability in high temperature and high salinity reservoir of conventional gel plugging agent, a heat resistant and salts tolerant instant gel plugging agent is developed composed of emulsion polymer, monomer crosslinker and stabilizer applicable to offshore oilfields. Through lab static evaluation experiments, the formula of gel plugging agent at 130 ℃ is optimized: 2.0%-3.0% emulsion polymer +0.6%-1.2% crosslinker +2.0%-3% stabilizer PE. The dissolution time of the gel system is about 20 mins at 30 ℃, its gelling time can be controlled from 4-11 hours, and the gelling strength grade can be adjusted from D to F. The experimental results show that the gel system is not dehydrated after 90 days of aging time in the conditions of high temperature (130 ℃) and high salinity (33 351 mg/L salinity, and the Ca2+ & Mg2+ concentration being up to 1 613 mg/L), showing favorable heat resistance, salt tolerance and shear resistance. The lab plugging and scouring resistance experiment of the typical gel plugging agent indicates that the plugging rate of the optimized gel formula is more than 96%, and the plugging effect of the gel is good, and the gel has good erosion resistance.