Development and Application of Non-acid Plugging Remover for Injection Wells

Jiangsu oilfield has entered the development stage of high water cut, and some water injection well formations have formed composite scales such as carbonate, sulfate, and oil sludge. Conventional acidification techniques are difficult to dissolve sulfate and organic scales, and the operating cost is high. Therefore, a non acid plugging agent is developed, which is mainly composed of ultra-low molecular weight polymers and added with auxiliary agents such as organic salts and non ionic surfactants. It is prepared using micro speed stirring and low-temperature synthesis. The experimental results show that: The non-acid plugging agent has good dissolution effect on marble, gypsum and mixed scale, and the dissolution rate is greater than 70% at 60℃ for 48h; At the same time, the dissolution rate of reservoir rock powder can reach 20%, which will not cause significant damage to the reservoir skeleton; The dissolution rate of reservoir rock powder can reach 20%, which will not cause obvious damage to the reservoir skeleton; The corrosion rate of N80 steel is 0.5g/(m2.h), which has good corrosion inhibition; In-door core damage removal rate is 90%. On site application of 6 wells, the average single well apparent water absorption index increased by 2m3/d MPa, the pressure reduction rate was 30%, the cumulative injection increased by 36000 cubic meters, and the validity period exceeded 400 days. This technology can effectively remove inorganic and organic blockages in the near wellbore zone, restore oil water permeability, improve water drive development effectiveness, and provide a new safe and low-cost means for increasing injection in oilfield water injection wells.