Deep water drilling riser mechanical behavior analysis considering actual riser string configuration

Abstract

A dynamic analysis model considering the actual riser string configuration is established to analyze the mechanical behavior of a drilling riser. The riser in this model is regarded as a simply supported beam located in the vertical plane and is subjected to axial and lateral ocean environment loadings. The model is solved using the finite element method. The validity of the analysis model has been proved by a similar experiment conducted in a deep water basin and ANSYS. Riser lateral displacement, bending moment, and deflection of the deep water well considering actual riser string configuration in South China Sea are simulated. The effects of top tension, drilling platform drift distance, surface current speed, wave height, wave period, wave length, wind speed and damping coefficient on riser lateral displacement, bending moment, and deflection are also discussed. Results indicate that riser string configuration has a significant effect on riser mechanical behavior, particularly in the distribution of bending moment. Riser string configuration designing according to concrete ocean environment can significantly improve the riser’s mechanical behavior. The distribution of riser lateral displacement, bending moment, and deflection increases with the increase in surface current speed and drilling platform drift distance, whereas decreases with the increasing top tension and damping coefficient. The distribution of riser lateral displacement, bending moment, and deflection significantly increases with the increase in surface current speed and large current speed may lead to large lateral displacement, bending moment, and deflection. Increasing top tension can significantly decrease riser mechanical behavior parameters and avoid large lateral displacement, bending moment, and deflection when suffering extreme ocean environment conditions in deepwater drilling field. Drilling platform should avoid a large drift distance, which may result in the deflection over the flex joint working range and the enlargement of the riser bend moment.