During the lifecycle, the operation of oil pipelines is associated with multiple inherent problems which include water and gas slugs forming at low and high points of the pipeline elevation profile. The multifactorial nature of the hydrodynamic interaction with the main flow makes the behavior of these structures difficult to predict, but at the same time they significantly affect the performance and safety of main pipelines increasing the pumping power consumption, hampering the operation of leak detection systems, causing oil metering issues, and corrosion-related risks. A rational way to avoid the complications associated with the water slugs is purging by pumped liquids since this method does not require the introduction of any additional equipment or chemical reagents in the internal cavity of the pipeline. The proper planning of these activities requires sufficient dependencies describing the conditions and intensity of water removal by the pumped fluid based on a solid scientific ground of carefully conducted experiments with qualified processing of the results. The problem of most studies in this area is that small-diameter pipelines are used for the experiments and additional justifications are required to scale up the results for industrial pipelines.
The article describes a unique test bench for studying behavior of water slugs in pipelines with variable profiles including DN100 pipe spools. Some experimental results from the test bench are presented. The computational fluid dynamics methods are proposed to simulate the processes of water slug removal by the flow of pumped liquid. Some equations applicable to the subject problem are also provided. The test runs of the resultant algorithms demonstrate a high level of agreement between the computed results and the data from the experimental studies on the test bench. The successful tests support the claim that the developed methodological basis is valid for scaling up experimental data to the existing oil pipelines.
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