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This paper identifies a field with challenging well operating conditions for OCTG Corrosion logging in gas well that include pressure, temperature, carbon dioxide (CO2), hydrogen sulphide (H2S) and well completed with high Ni corrosion resistant alloys (CRA). This case study, describes how periodic well interventions to measure the wall thickness of various strings, required specialised technologies in gas well to the high chromium and nickel content in the tubing which reduces the magnetic properties of the string(s). All well interventions require careful tool selection, planning and implementation, however when the conditions are extreme and present HSE related issues, the planning must reflect a greater level of detail and understanding. Additionally, the logging and interpretation process required for high end CRA tubulars is more detailed and sophisticated and little public domain data is available to assist in the well programme implementation. The Operator required logging tools to be fitted with highly sensitive and fast responding sensors, housed in titanium casings and run in memory mode with a slickline conveyance. In this case study two wells were logged with multibarrier corrosion logging tools combined with multi-finger calipers, to determine tubing and casing thickness status of three tubular barriers. The flow wetted areas were completed with high end chrome/nickel tubulars with potential challenges for data acquisition and subsequent analysis. However, pre-logging planning was supported and bench marked by yard testing where identical composition materials had been used. On retrieval, the data package showed provided a composite set of data, throughout the well and log interpretation clearly identified the well status to be positive. This provides excellent support for the applied logging technology. Pre-logging data searches within SPE and other locations for academic papers describing similar scenario could not be found and this paper is understood to be the one of first kind. These specialized principles and procedures likely to provide with much needed BASE CASE guideline for such future corrosion monitoring logging in similar field conditions. |
