The wellbore downhole strings corrosion has attracted extensive interest as most of the oilfields in China enter the high water-cut period. Injection of corrosion inhibitors, one of the most effective corrosion protection methods, is employed to mitigate the wellbore corrosion. Nevertheless, its wider application suffers from insufficient knowledge regarding the distribution of corrosion inhibitors inside the tubing, particularly with different inhibitor injection cycles. Thus, in this study, the computational fluid dynamics (CFD) method was first attempted to investigate the hydrodynamics in a tubing and the interactions between the corrosion inhibitor and produced fluid with high water-cut. Key factors including the time, wellbore heights, injection rates, oil phase velocities and corrosion inhibitor viscosities were discussed in detail as regards how they affect the corrosion inhibitor distribution inside the tubing. Feasible formulas were established for predicting the volume fraction of the corrosion inhibitor at different wellbore heights, which showed good agreement with the simulation results. It is noted that the determination of the corrosion inhibitor injection rate depends on both the film quality of the corrosion inhibitor and the stability of the annular flow. Based on the interphase diffusion effect, a new method for determining the intermittent injection cycle of corrosion inhibitor was proposed to maintain the integrity of corrosion inhibitor film at the tubing inner wall.
The corrosion behaviour of J55 steel in typical high-water-cut oil wells and the inhibition effects of different types of corrosion inhibitors were investigated. Using electrochemical experiments, the effects of temperature, Cl−, HCO3−, Ca2+, Mg2+ and pH on the corrosion of J55 steel were studied. Under experimental conditions, the corrosion rate slowed with increasing pH value when the temperature increased from 35 °C to 70 °C. The corrosion rate also increased first and then decreased with increasing Cl−, Ca2+ and Mg2+ ion concentrations, which notably affected the distribution of corrosion pits on the surfaces of the steel. The protection performances of various corrosion inhibitors and corrosion products were evaluated through electrochemical measurements. The results showed that the CT-2, UT2-2 and YC-2 inhibitors had obvious effects on the corrosion prevention of the J55 steel. In particular, the corrosion inhibition efficiencies of the three kinds of carbon steel were remarkable and exceeded 84% when the UT2-2 concentration reached 0.18 g/L.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.