Greater Kittiwake Area (GKA) well KA-15, while not a significant oil producer anymore, provides large amounts of hot produced water which assists the field's first stage separation process. Historically, there have been numerous records of significant metal loss in the carbon steel flowline, especially at bends and welds, attributed to the line's convoluted configuration, flow rates and associated potential for erosion-corrosion effects.
This paper outlines the investigation process and corresponding findings. For fluid velocity calculations, computational fluid dynamics (CFD) was employed to allow highly accurate determination of the fluid velocity profile as well as the magnitude of localised wall shear stress. This was so as to assess the efficiency of the applied corrosion inhibitor and to provide a means of well management to avoid exceeding erosional velocities. In addition, a thorough review of the input parameters used for the corrosion inhibitor selection was performed; this revealed that erroneous inputs and inadequate testing were used for laboratory qualification of the chemical, with detrimental consequences for the flowline's integrity.
The study eventually concluded that the original material selection for the flowline was not appropriate for at least the current operating conditions and chemical testing was performed on unverified assumptions. This highlights the importance of using accurate methodology to validate inputs and that of periodic in-depth system reviews to ensure that new field parameters are re-evaluated correctly.