US Patent 7630866 Method of dimensioning a drilling riser

The present invention relates to a method of dimensioning a riser assembly (1) intended for offshore drilling, connecting an underwater wellhead (2) to a floating support (7) comprising a main pipe (8), wherein the following stages are carried out:selecting a complete architecture for the riser assembly from specifications, notably by fixing the thickness of the main pipe and of the buoyancy means, and calculating the apparent weight of this assembly,determining the tension margin at the top of the 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 the assembly is suspended,in cases where the tension margin corresponds to a value close to a determined value, calculating the Von-Mises stresses in all the sections of the pipe, when connected to the wellhead,in cases where the stresses are close to a criterion determined in connection with the yield limit of the material of the pipe, checking by calculation the load on each component of the riser assembly and its fatigue under dynamic conditions.