3D mechanical analysis of subsea manifold installation by drill pipe in deep water

Taking the vessel's RAO (response amplitude operator), wave and lowering velocity into consideration, a 3D mechanical analysis of a manifold installation by a drill pipe in deep water is presented in this paper. On the basis of the small-deformation bending theory, the theoretical formulas of displacements, axial tension, bending moment and inclination along the drill pipe are derived by finite-element discretisation. The key results obtained from the proposed method are compared with the ones achieved from the finite-element model using OrcaFlex and the results are in good consistency. A series of sensitivity analyses are also presented to highlight the most influencing parameters in the installation. The proposed method is useful for the feasibility study of the manifold installation.