Quasistatic Nonlinear Analysis of a Drill Pipe in Subsea Xmas Tree Installation

Abstract

To analyse the stress and deformation of a drill pipe during the lowering of a subsea Xmas tree, a mechanical analytical model and equation were established based on Euler-Bernoulli beam theory. The wave phase is selected as one of the variable parameters for analysis of the deformation and stress of the drill pipe. The research results indicate that the maximum response occurs at 0 radians in the scope of 0 to 2π, and the quasistatic nonlinear analysis is analysed at 0. In addition, Orcaflex software is applied for simulation, and the simulation results are compared with the results from proposed method, which demonstrate the model and the method accuracy. Factors that affect the installation process are discussed, such as current velocity, wave height, pipe size, and towing speed. The results show that all factors have remarkable effects on stress and deformation and that the wave height has a lesser effect on the deformation of the drill pipe. The viable towing speed is chosen by discussing the total stress of the drill pipe with various towing speeds and is notably useful for installation in the real sea state.