Study Of Corrosion And Protection Of Low-permeability Oilfield Gathering & Transporting Process In CO₂ Flooding

With oilfield development entered the high water-cut stage, increasing peripheral low permeability and low porosity block of exploration and development efforts have become more important in crude oil production, to realize the sustainable development of oilfield. According to the reservoir characteristics of low permeability reservoirs, CO2 flooding showing the unique advantages, the existing indoor experiment and field application show that CO2 flooding in low permeability oilfield development production efficiency has a good adaptability and development prospects.In oilfield development engineering ground underground integration background, compared with the traditional oil displacement technology, CO2 flooding to improve oil recovery technique in the surface gathering process reveal some new problems, among them with pipeline, gathering, processing, equipment corrosion problem of the most prominent, corrosion perforation phenomenon occurs frequently, directly affects the normal production operation of the gathering system.Then, this article in view of the low permeable oil fields of CO2 flooding produced liquid corrosion problem of surface gathering and processing facilities, as an object in daqing yushulin oil field, in the gathering and processing technology on the basis of the studies of the system, selection of appropriate node extraction liquid sampling analysis, through the indoor corrosion simulation experiment, the characteristics of produced liquid’s influence on the corrosion behavior was studied; In the transfer station to select heating and sedimentation separator the unity of partial node to carry out the dynamic coupon corrosion experiments.With energy spectrum analysis, electron microscope scanning and gas composition of chromatographic analysis of qualitative and quantitative characterization of the nature of the corrosion products, and the analysis of the corrosion mechanism of CO2 flooding produced fluid, the influence factors of the corrosion rate.Finally, in view of the low permeable oil fields of CO2 flooding produced fluid corrosion behavior, combined with field anti-corrosion technology application situation, proposed the CO2 flooding gathering facilities corrosion protection technique.The research results show that of CO2 corrosion of carbon steel material is mainly affected by temperature, concentration of Cl-, CO2 partial pressure, the influence of the corrosion rate increases with the increase of temperature, when the temperature is highter than 80℃ the corrosion rate showed a trend of decrease after due to the density of the formation of corrosion product film; With the increase of Cl-concentration, corrosion rate increases, and the pitting behavior is more serious;With the increase of CO2 partial pressure, corrosion rate showed a trend of increase, at the same time scale.The corrosion mechanism of CO2 flooding produced fluid mainly lies in the early stage of corrosion caused the electrochemical corrosion, along with the formation of the corrosion product film and corrosion scale, scale and corrosion is accelerated, resulting in serious pitting corrosion, pit corrosion, etc.Is given priority to with glass or carbon steel inner liner using nano coating in corrosion protection technology of CO2 flooding gathering facilities has good applicability and operability.The results of the study of CO2 flooding surface gathering process of corrosion protection work is of important guidance value, but also is beneficial to promote the further popularization of the technology of CO2 flooding of low permeability oilfield application.