Prediction of the Minimum Depth of Setting for Conductor Anchor Node in Deep-Water Drilling

When deep-water oil-gas fields adopt the conductor anchor node(CAN) for surface well construction, the wellhead may suffer from collapse, or the formation is too hard to run it in place. On the basis of analyzing the running principle of the CAN, a bearing capacity model of the CAN considering the effects of installation effect was established. In view of the most dangerous working conditions during the second spud cementing, the formula of maximum wellhead load during drilling was derived, and a depth of setting model for the CAN based on the bearing capacity was established by considering the safety factor of the pile foundation. Through the calculation model of the setting depth, the minimum depth of the setting in mud of the CAN of Well X in the South China Sea was 10.56 m. On the basis of the environmental parameters of Well X in the South China Sea, a finite element model was established by ABAQUS software, and the vertical bearing capacity of the wellhead suction pile was calculated to be 8 593.22 kN. At the same depth of setting in mud, the bearing capacity was theoretically calculated to be 8 063.59 kN, with an error of 6.16%, which reflected a high accuracy. The research revealed that the depth of setting model for the CAN based on the ultimate bearing capacity could accurately predict the minimum depth of setting of the CAN and effectively improve the safety of the subsea wellhead during the installation and drilling stages.