关键词: 输油管道, 油水两相流, 壁面剪切力, 流速, 含水率, CO₂腐蚀

Abstract:

At present, water injection is often used to extract oil, but CO₂ corrosion often occurs in water?bearing pipelines. Therefore, Computational Fluid Dynamics (CFD) was used to study the distribution of oil and water in straight pipes and bends at different water content (volume) and flow rates, to determine the conditions for the occurrence of CO₂ corrosion in oil pipelines, and the effect of flow rate and water content on the wall shear force was analyzed. The results show that the occurrence of CO₂ corrosion depends on the water content and flow rate in the pipeline. When the water content increases, oil infiltration in the inner wall of the pipe to prevent corrosion; when the water content decreases, the amount of water accumulation increases, resulting in serious CO₂ corrosion. When the flow rate increases, turbulence occurs in the pipeline, so it is difficult to form water accumulation, reducing the risk of corrosion. However, an increase in flow rate will lead to an increase in wall shear, which will destroy the corrosion product film and further accelerate the corrosion rate. In downward elbows, under the action of gravity, water often does not occur in the pipeline, and the risk of corrosion is low; in upward elbows, water is most likely to occur, and the risk of corrosion is high; affected by scouring, the elbow end is corroded seriously. The elbow end is susceptible to the interaction of corrosion and mechanics, so corrosion is serious. The research results have certain guiding significance for the safe operation of oilfield gathering pipelines.

Key words: Oil pipeline, Oil?water two?phase flow, Wall shear stress, Flow rate, Water content, CO₂ corrosion