Breaking Down And Augmented Injection Research For Water Injection Wells In Panlong Oilfield

In the process of exploration and development of the oilfield, the permeability in the near-wellbore zone will decrease due to the plugging of injection wells, resulting in phenomenons such as increased injection pressure, weak water absorption capacity of the reservoir, and decline of oil production. This problem is particularly evident in low permeability oilfield. Based on the literature review, this paper systematically studied the typical geologic features of Chang 2 reservoir, which shows the typical ultra-low porosity and ultra-low permeability charateristics. The pore types of Chang 2 are mainly secondary intergranular pores and dissolved pores. According to the sensitivity evaluation experiments, the reservoir shows strong velocity sensitive, weak water sensitive, weak alkaline sensitive, weak salt sensitive, weak acid sensitive and so on. Based on the status quo of water flooding development, this paper also studies the types and causes of the plugging of water wells in Chang 2. Through reviewing and referencing a large number of documents, the causes of water injection pressure include water quality factors, geological factors, reservoir damage, etc. The study shows that the plugging of the target reservoir is mainly caused by incompliance water quality and reservoir velocity sensitivity.Conventional plugging in the target area of reservoir acidification is not complete, and the duration is short, easily leading to plugging again. To solve this problem, the PA, PB and PC slow acid systems were optimized according to the characteristics of target reservoirs, and the acidification and plugging effect was evaluated from acid system, reaction time and post-slug acidification effect. The results showed that the acid of three kinds of retarded acid systems have good plugging effect. Retarded acid system PC increased the core permeability of Chang 2 by 56 times, and acidification of pollutants shows a better role in removing plug. The acidified PC was used in wells feng 97-5 and Pan 2015, and the field test showed that PC slow acid had a good effect in the target well. The unblocking system can provide a reference for the exploitation of low permeability oilfield.