Analysis on Deepwater Drilling Conductor-Soft Soil Interaction Characte ristics and Fatigue Effects Under Horizontal Load
In the process of deepwater drilling,the conductor is subjected to complex horizontal loads,the conductor-soft soil interaction characteristics need to be further studied,and the influence of soft soil action on pipe string fatigue is not yet clear.Therefore,the finite element software was used to build a numerical analysis model for the interaction between deepwater drilling conductor and soft soil,and study the influence of horizontal loads on the shear force and bending moment of drilling conductor in clay and sand ground models.Moreover,the fatigue life of drilling conductor was analyzed by considering 3 kinds of load forms:unidirectional cyclic load,bidirection-al asymmetric cyclic load and bidirectional symmetric cyclic load.The study results show that in clay ground,due to small soil reaction force,the conductor exhibits greater bending moment and shear force,and will suffer from severe fatigue damage under long-term cyclic stress;in sand ground,the fatigue damage of conductor only exists in shallow position,and the fatigue life is obviously longer than that of the conductor model in clay ground;when the subsea shallow formation is clay,measures need to be taken to reduce the horizontal load on the top of conductor and change the loading form to improve the fatigue life of the drilling conductor.The conclusions provide a basic guarantee for the safety and stability of the operation site.
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