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Pipeline in-line inspections (ILI) are one of the primary methods used to assess the integrity of operating oil and gas pipelines. Conventional ILI technology is based on ultrasonic testing (UT) or magnetic flux leakage (MFL) sensors. Although these technologies are suitable for most pipeline inspections, there remains an opportunity to expand ILI technology and application. ExxonMobil and Innospection Ltd. are working to develop a new ILI sensor technology based on a combination of Magnetic Eddy Current (MEC) and multi-differential eddy current. This new technology provides the potential to detect small volumetric features, inspect heavy wall gas pipelines, and inspect pipelines with corrosion resistant alloy (CRA) or non-metallic liners. Initial feasibility trials were conducted with a prototype ILI MEC tool. Tests were conducted on an 8.625” (219 mm) X65 carbon steel pipe lined with 0.118” (3 mm) of Inconel 825 pipe. Four types of defects were machined into the pipe to represent natural defects anticipated in service: • Metal loss features from 3 to 24 mm in diameter on the external surface of the carbon steel base pipe • Erosion on the internal layer of the CRA liner • Internal girth weld crack-like defects • Metal loss defects at the interface of the CRA and carbon steel Over 80 pull tests were conducted to determine the detection capabilities and speed sensitivities of the tool. Defects were detected by the sensors including the very small (<10 mm) pinhole-type features. Signals were analyzed by a preliminary sizing algorithm to demonstrate proof of concept. Detection performance was not affected at speeds up to 0.75 m/s. Since detection capabilities exceeded expectations, future development will continue based on the current prototype.

Pipeline in-line inspections (ILI) are one of the primary methods used to assess the integrity of operating oil and gas pipelines. These inspections can be complicated to conduct due to a variety of reasons ranging from operational limits (high/low flow velocity, wall thickness, pipeline extreme depth or pressure, etc.) to limits inherent to the inspection technology. Often these complexities are overcome with tools customized to a specific pipeline. Although this has been effective for singular pipeline inspections, a more industry-wide approach should be considered to develop broader solutions. This paper discusses the opportunities to enhance ILI and suggests a ranking of priorities for technology development.

TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractLarge diameter subsea pipelines are being used across the world for wet gas transportation over significant distances from offshore fields to onshore facilities. The ability to predict and control corrosion is necessary to ensure long term integrity of these pipelines. Large diameter wet gas lines operating in stratified flow pose unique challenges for top of the line corrosion which occurs when corrosive gases are found dissolved in condensed water at the top of the pipe. This paper will discuss a study undertaken by ExxonMobil 1 and RasGas to establish a mechanistic understanding of sour top of the line corrosion and the operational guidelines developed to control its occurrence.