Abstract

In a marginal and aging asset, ensuring the pipeline integrity plays an important role in order to maintain fluid transmission. Shutting off a single pipeline could jeopardize the overall asset operation. This paper presents a methodology for the identification, assessment and mitigation of dragged submerged pipelines.

As part of Pipeline Integrity Management, the inspection of an anchor-dragged submerged pipeline was carried out with the aid of a Remotely Operated Vehicle (ROV) equipped with pipe-tracker module. This enabled us to determine the extent of the pipeline alignment deviation, as well as to conduct a close visual inspection of the pipeline. With the information retrieved from the inspection, a fit-for-purpose pipeline drag analysis was performed to assess the pipeline integrity. The pipeline was simulated using the Finite Element Analysis (FEA) methodology which considered various axial and lateral soil friction factors to achieve the closest approximation of the pipeline's actual condition. Once the best-fit parameters were determined, code checks were performed in accordance with the DNVGL-ST-F101 [1] international standard to assess the acceptable pipeline operating envelops. This assessment results provide the inputs to develop the mitigation plans required to safely keep the pipeline in operation until the pipeline repairs can be executed.

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