Patent ID: 7630866

Claim:
A method of dimensioning a riser assembly intended for offshore drilling, connecting an underwater wellhead to a floating support comprising a main pipe, wherein the following stages are carried out: a) selecting a complete architecture for the riser assembly from specifications, including by fixing the thickness of the main pipe and of buoyancy elements, and calculating the apparent weight of this assembly, b) determining the tension margin at the top of said assembly, when disconnected from the wellhead, considering the apparent weight and the tension amplified at the top by the motion of the floating support from which said assembly is suspended, c) in cases where said tension margin corresponds to an acceptable determined value, calculating the Von-Mises stresses in all the sections of the pipe, when connected to the wellhead and, in cases where said tension margin does not correspond to an acceptable determined value, modifying an aspect of the architecture for the riser assembly to approach an acceptable determined value and redetermining said tension margin, and, d) in cases where said stresses correspond to an acceptable criterion determined in connection with the yield limit of the material of the pipe, obtaining the architecture of the riser assembly and checking the compatibility of each component of the riser assembly at the maximum tension value, and the fatigue under dynamic conditions of said assembly, and, in cases where said stresses do not correspond to an acceptable criterion, modifying an aspect of the architecture for the riser assembly to approach an acceptable determined criterion and redetermining said stresses.