Abstract
Subsea pipelines carry oil or natural gas over long distances of the seabed, but fluid leakage due to a failure of the pipeline can culminate in huge environmental disasters. Scouring process may take place beneath pipelines due to current and/or wave action, causing pipeline suspension and leading to the risk of pipeline failure. The resulting morphological variations of the seabed propagate not only below and normally to the pipeline but also along the pipeline itself. Therefore, 3D scouring patterns need to be considered. Mainly based on the experimental works at laboratory scale by Cheng and coworkers, in this study, Artificial Intelligent (AI) techniques are employed to present new equations for predicting three dimensional current- and wave-induced scour rates around subsea pipelines. These equations are given in terms of key dimensionless parameters, among which are the Shields’ parameter, the Keulegan–Carpenter number, relative embedment depth, and wave/current angle of attach. Using various statistical benchmarks, the efficiency of AI-models-based regression equations is assessed. The proposed predictive models perform much better than the existing empirical equations from literature. Even more interestingly, they exhibit a clear physical consistence and allow for highlighting the relative importance of the key dimensionless variables governing the scouring patterns.
Highlights
Seabed pipelines are imperative to transport oil and gas from offshore platforms.Oil leakage due to failure of pipeline causes environmental disasters, which influence economic circumstances of nations
Three-dimensional scour rates depend on several factors, namely pipeline geometry, wave properties, embedded depth of pipeline compared to the initial level of seabed, and physical properties of seabed sediments (e.g., Cheng et al [6], Wu and Chiew [8], Cheng et al [9], Wu and Chiew [31])
This represents a limitation for the current available datasets, and further investigations on clear-water regime and various sediment beds would be of interest
Summary
Seabed pipelines are imperative to transport oil and gas from offshore platforms. Oil leakage due to failure of pipeline causes environmental disasters, which influence economic circumstances of nations. The scour hole grows longitudinally around the pipeline, the structure free is developed. Fully developed free are spans thereason main that reason that pipeput into failure In this the case, failure pipelines is due toisthe fact theythat are lines are aput into astate. Failure state.case, In this theoffailure of pipelines due tothat the fact moreare exposed to structural destructions corresponding to over-stressing circumstances They more exposed to structural destructions corresponding to over-stressing circumThe earliest experimental investigations proved that the formation of three-dimensional stances. Free spans can lead to natural self-burial into the scour hole formed pipeline. Free spans can lead to natural self-burial into the scour hole below the pipeline (Sumer and Fredsøe [2]).
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