Global Buckling Of Subsea Pipelines And Pipe-Soil Interaction

Since the1970s, oil development in the deepwater is considered as an important frontier in the oil industry. In the Gulf of Mexico, Brazil and West Africa, oil development in the deepwater has made significant progress. In China, oil and gas fields of the East China Sea are developing currently, and rich oil and gas resources also have been discovered in the South China Sea at1000m depth. As the offshore oil industry promoting to the deepwater, the design temperature of subsea pipelines may exceed100℃, thus the pipeline tends to buckle laterally due to the high compressive force caused by thermal expansion. Such global buckling may cause damage of the pipeline, which is one of the main reasons for pipeline breakage.Thermal stability of the whole pipeline and modeling of the pipe-soil interaction process are the two important aspects related to the problem of global pipeline buckling, which are exactly the focus of this paper. In this paper, analytical solutions for global pipeline buckling have been extended, and the mechanism of pipe-soil interaction have been analyzed and discussed.From the above, the main contributions of this work include:1. An analytical model has been established for the problem of a single force to trigger global pipeline buckling, and the critical axial force as well as the critical temperature rise have been obtained under a given triggering force.2. The classical analytical solution of vertical pipeline buckling on a rigid seabed has been extended to a soft seabed, and the influence of seabed resistance on the whole buckling process has been analyzed and discussed.3. The required buoyancy force and sleeper height to trigger lateral buckles have been solved through analytical and FE methods respectively. And the influence of the lateral seabed stiffness on the required buoyancy force and sleeper height has been presented.4.The influences of the initial imperfection, seabed resistance and nonlinear of the pipeline material on the dynamic effects of global pipeline buckling have been investigated through FE method.5. The mechanism of pipe-soil interaction has been analyzed though FE method. The failure modes through the whole pipe-soil interaction process have been analyzed, and a new failure for lateral pipe-soil interaction has been presented. In the same time, limitations of existing pipe soil interaction models have been discussed.