Research On Mechanical Modle Of Deepwater SCR Installation Based On Pipe-Soil Interaction In TDP

With China having entered a substantive development stage for oil and gas resource, Steel Catenary Riser (SCR) as major equipment for development of deepwater oil and gas resources, its installation technology research has been attached more and more importance. Supported by national 863 "deepwater submarine pipeline laying technology" program, based on obtaining an approximate analytical expression of mechanical model for deepwater SCR installation, the prediction formula of pipe-soil interaction force considering the velocity parameter is proposed in this paper by the pipe-soil interaction test, and the deepwater SCR installation mechanical model that considered the Touch Down Point (TDP) pipe-soil interaction is then studied. Finally, a model test investigation on deepwater SCR installation process using hybrid model testing is attempted.Main innovations of this paper are summarized as follows:(1) The shape control for deepwater SCR in the installation process is crucial for the safety of SCR. For the problems and challenges of the small deformation beam theory and catenary theory during the riser installation analysis, riser mechanical model based on large deformation beam is proposed, simulating the deep-water SCR installation process more accurately. And the approximate analytical expression based on the homotopy analysis method is obtained. This form of the approximate analytical expression is relatively simple, providing a new approach for the calculation of deepwater SCR installation.(2) It is difficult to simulate the complex nonlinear pipe-soil interaction accurately. A simple pipe-soil interaction test system is established in this paper. The test system can simulate the pipe-soil interaction in vertical and lateral direction. Based on the experiment research, the backbone curve prediction formula and adsorption prediction formula considering the riser velocity factoris is proposed, and the mechanical model of SCR installation that cosnsidering the pipe-soil interaction is proposed, which has great importance for simulating the pipe-soil interaction at TDP accurately.(3) For the linear spring and rigid seabed is difficult to meet the precise simulation requirements, a new mechanical model is established using the pipe-soil interaction model in this paper, and the SCR shape and bending moment in different types of soil properties are analyzed. (4) For the problems and challenges encountered in the model test of deepwater SCR installation, the active truncated test method for deep-water SCR installation is proposed, and a deep-water SCR installation simulation system is developed. Through the testing research, the accuracy of the test method is verified. This research provides a new way for deepwater SCR installation test research.