The majority of the deepwater pipelines operating in the Gulf of Mexico (GoM) carry hydrocarbons at a high pressure and temperature resulting in the system's thermal expansion. In order to relieve the high stresses due to thermal expansion, these pipelines are designed to use buckle triggers in order to buckle laterally at pre-determined locations. Since these assets are expected to last a few decades, it is imperative that a robust long-term integrity management program is in place to effectively operate these pipelines, monitor their long term performance, verify design assumptions and thus, reduce any potential risks. As a part of BP's comprehensive In Water Integrity Management (IWIM) program, three pipelines were surveyed during a 2012 Multi-Beam Echosounder (MBES) survey campaign. The surveys checked for buckle initiation, buckle locations and obtained accurate buckle shapes to allow subsequent integrity assessments to be performed. Ten out of ten planned buckles formed across the three operational pipelines; a mixture of sleepers and buoyancy modules initiated these buckles at pre-determined locations. Smaller buckles were also observed at unplanned locations in the pipeline system. These pipelines terminate at subsea structures situated at the ends of the pipelines. In order to track the pipeline's long-term global movement; the end displacements at these structures were recorded as well. During its operation, a pipeline system will be shut-down and re-started multiple times, thus creating a series of thermal cyclic loadings. In order to ascertain the long-term performance of the pipelines under such sustained thermal loading cycles, a Finite Element (FE) model is built using the pipeline data, seabed bathymetry and other environmental conditions. The FE model is calibrated using the recorded 2012 MBES survey in-service pipeline lateral buckling profiles. The calibrated FE model generates axial stress ranges at critical locations (buckle crown); these stress ranges are subsequently used to perform fatigue analyses. The estimated fatigue damage is used to forecast the pipelines' long-term fatigue performance, which will determine the future inspection and monitoring plans. This paper presents an overview of the 2012 MBES Survey conducted on three of BP's operational pipelines as well as the subsequent FE and fatigue analyses performed to assess the long-term integrity within lateral buckles.
Integrity management (IM) is an ongoing lifecycle process for ensuring safe operation and fitness for service of offshore oil and gas production systems, including riser and flowlines. Riser and flowlines offer a means of transporting fluids between subsea wells and the host platform. A key component of the riser system is above water riser hull pipes. With their proximity to topside equipment and the people on the platform, these pipes are considered safety critical, and are therefore, subject to rigorous and frequent inspections followed by an engineering assessment of the findings. A thorough knowledge of the past and current conditions of these pipes is required to manage the risk to their integrity. Traditionally, these inspections are carried out by rope access technicians. Such activities are often limited by accessibility, weather, and/or Personnel on Board (POB) availability and involve risks to inspector's safety. This paper discusses the motivation and business driver for developing and implementing new robotic inspection technologies for above water riser inspection. The technology management process of robotic inspection tools is outlined. Comparison is made between traditional and new inspection technologies based on BP Gulf of Mexico (GoM) robotic inspection campaigns. Examples are presented to demonstrate the reduction of safety risks and improvement of inspection execution and effectiveness. The paper also discusses the potential areas of future development, which include methods for pipe wall thickness measurement and data analytics, such as automated recognition approach to characterize and quantify features in the images.
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