Failure Characteristics and Numerical Simulation of Corrosion Control in Welding Seams and T-Zone of the Water Injection Pipeline

Abstract The water injection pipeline is the main facility of water injection development in oilfields. With the complexity of water injection mediums and the extension of service years, the frequency of pipeline corrosion failure increases year by year. Corrosion failures are particularly prevalent at welding seams and T-zones, but a comprehensive understanding of their corrosion characteristics and mechanisms remains limited. Therefore, this article studied corrosion failure behaviors of welding seams and T-zone in water injection pipelines under typical working conditions through laboratory experiments and numerical simulations and proposed the anticorrosion measure of the loose joint “blind pipes.” The results indicate that combined effects of solid particle erosion, galvanic corrosion, crack corrosion, and under-deposit corrosion cause different degrees of cracks in the corrosion product layer of the water injection pipeline, ultimately forming compounds such as Fe2O3 and Fe3O4. As flow velocity increases, flow field changes become more pronounced in welding seams and T-zone, exacerbating erosion and corrosion. However, compared with small-bore pipelines, the erosion and corrosion are alleviated with the increase in diameter. In addition to anticorrosion coating and adding fungicide to the injection medium, the application of loose joint “blind pipes” effectively stabilizes the flow field, thereby reducing both flow velocity and corrosion rates in the T-zone. When the length and diameter of the blind pipe meet L = 3D, the maximum flow velocity and corrosion rate decrease by 8.9% and 23.8%, respectively, which effectively helps to prevent and control corrosion perforation in high-pressure water injection pipelines.