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The integrated stability analysis of offshore pipelines
Offshore Pipelines development is an extremely important topic in the energy industry as more oil and gas resources exist in deep, remote, offshore areas. Pipelines have proved to provide a cheap and reliable transport for these hydrocarbons. However, transporting hydrocarbons in extra-long offshore pipelines poses many challenges that must be considered when designing pipelines. These include stability of pipeline structures under the action of severe hydrodynamic loading of wave and current.
My research investigates the stability of the on-bottom pipeline under the action of wave and current loading using deterministic and statistical analysis methods. In statistical analysis approach the design evaluation accounts for the variability and uncertainty in the key parameters included in the pipeline stability analysis.
The objectives of my research are:
1-Develop software to calculate the hydrodynamic loads on an on-bottom pipeline. This will be included in a general software code, based in finite element package ABAQUS, to simulate the hydrodynamic-pipe-soil interaction behaviour of on-bottom pipeline.
2-Use the deterministic and statistical analysis approaches to address the probability response of pipeline to random variation in the soil, pipe and hydrodynamic loading parameters.
3- Specify quantitatively the most important variable(s) in the on-bottom pipelines analysis.
The commonly used approach in the pipeline design to overcome analysis simplification and variables uncertainty is by using safety factor. This has several limitations. It tends to be overly conservative for many practical situations and it does not provide any quantification of the design reliability. The former has obvious economic implications and the latter fails to deliver the needed input for the risk evaluation.
The results of my research are expected to lead to a better understanding of the complex hydrodynamic-pipe-soil interaction analysis with the presence of input parameters uncertainties. This aimed to help in forming an accurate pipelines design tool, achieving an economical design and maximizing the design reliability.