Prediction of “Classic” and “Flow-Induced” Internal Pipeline Top-of-the-Line Corrosion (TLC) Mechanisms using ICPM : Model Prediction Confirmation and Applicability in Gas Condensate Pipeline Operations

This paper is an update of an ACA (Australasian Corrosion Association) paper on a recurring and complex degradation issues where internal top-of-the-line (TOL or TLC) corrosion problems in a mature Alberta, Canada gas field have been observed over many years.  An aging pipeline system  (40+ years) with persistent TLC issues have been prevalent for almost half of the operational life with the problem indiscriminately appearing at various locations.

Internal corrosion predictive modeling (ICPM) using a wet gas ICDA approach was performed on 17 pipeline regions and an associated 79 pipeline subregions in an attempt to unravel the nuances associated with several TLC problems scattered throughout a large gas production and gathering system.  The ICPM modeling platform utilized Broadsword’s proprietary model.  It became readily apparent from the early modeling; the pipeline system likely had other corrosion mechanisms occurring in the remaining pipe body which were inextricably linked by the operational dynamics of the system.  Specifically, the active corrosion mechanisms are derived from the fluid hydrodynamic and mass transfer interactions of the wet gas.  The bottom of the pipeline cannot be ignored in the context of TLC.  It was found that annual mist flow regimes exacerbate TLC "grooving" or "streaking".