Study On Lateral Buckling Behavior And Walking Mechanism Of HT/HP Subsea Pipelines

With the development of the offshore oil and gas resources, submarine pipeline has been widely used in the offshore oil and gas transportation. In order to meet the requirements of oil transportation technology, oil and gas must be transported in the condition of high pressure and temperature, which always leads to expansion of submarine pipelines to produce high axial force, and induces the occurrence of global buckling and walking phenonmenon. Thus, it is significant to study lateral buckling and walking mechanism of submarine. Numerical simulation method was applied in this paper to study the mechanism and analysis approaches of pipelines’ global lateral buckling and walking, and to explore the mechanism of interaction between the two phenonmenon. The main research contents are as follows:The theories of pipeline buckling was summarized in this paper and understand the research status of pipeline lateral buckling and the difficulties faced by the study. Based on this, a nonlinear finite element model with initial defection is established, which considered the pipeline geometric nonlinearity, material nonlinear and pipe-soil nonlinear interaction. The comparisons between analytical and numerical results validate finite element method suggested in the paper.For different initial geometric imperfections, pipe-soil interaction form and pipe cross-sectional shape of the pipeline, a nonlinear finite element model is established by using ABAQUS software. This paper introduces the improved Riks method to analyse the subsea pipeline lateral buckling characteristics, simulate pipeline buckling and post-buckling shape under different parameters, and consider the influence of internal pressure on the pipeline buckling characteristics.This paper establish the finite element model of a short and straight pipeline under nonlinear cyclic temperature load. And reveal the formation reasons of pipeline axial walking phenomenon and the law of development. It also focus on the effect of axial friction factors related to pipe-soil interaction and the pipe internal pressure. At last, this paper briefly deals with possible mitigation options to prevent pipeline walking.Interaction between pipe walking and lateral buckling is studied in this paper. Thus, a numerical model of pipelines on the flat seabed with initial defection is established by the finite element method. Analyse the effect of two different pipe-soil interaction model to the buckling characteristics of pipeline and the axial movement rate.