Evaluation of Wall Shear Stress in Multiphase Flow and Its Effect on FeCO? Removal

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Product Number: 51315-5922-SG

ISBN: 5922 2015 CP

Author: Wei Li

Publication Date: 2015

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Fluid transport through pipelines is a common operation in the oil and gas industry and fluctuations in production rates in these pipelines over time mean that the wall shear stress experienced by the internal walls of the pipeline will also vary with time. Multiphase flow in these pipelines i.e. slug flow is considered to be a highly turbulent flow regime and its effect on corrosion has been discussed for decades. However the effect of turbulence and particularly mechanical forces produced by flow on corrosion product layers and inhibitor films are not fully understood. Wall shear stress (WSS) is one of the most important parameters used to characterize flow conditions and to assess the influence of flow on corrosion. Under controlled laboratory conditions a wide range of flow regimes in water (single phase flow) and gas/water (stratified flow slug flow and annular flow) systems have been used to measure WSS using a direct WSS measurement probe pressure drop measurements and flow rate measurements including visual observations by a high speed camera. In addition atomic force microscopy (AFM) has been used to quantitatively study the force required to remove FeCO3 crystals from a pipeline steel.While the highest WSS measured was approximately 100 Pa in ambient pressure systems analytical measurements by AFM indicate that forces on the order of 10 MPa would be required to remove an iron carbonate precipitate from a mild steel surface. This is an important finding which indicates that the WSS from fluid flow in transport pipelines is not sufficient to damage FeCO3 layers which could lead to localized corrosion.Keywords: Two-phase flow; wall shear stress measurements; flow loop; slug flow; AFM.