Operating Capability of Big-foot Jack-up in China’s Offshore

There are some offshore oilfields that have comparatively low shear strength cohesive soils in China, which means very deep penetration for most of the jack-ups. To develop these fields more efficiently, a kind of big-foot jack-up is introduced. A larger spudcan may result in shallower penetration but larger extraction resistance, which may make the jack-ups difficult to pull out. To evaluate the operating capability of the big-foot jack-up, both the penetration and extraction capability at all well sites of offshore China are calculated. It is shown that larger spudcans enable the rig to penetrate much shallower in soft soils, and the possibility of punch-through in all fields is reduced too. To improve the extraction capability of the rig, the jetting system is redesigned based on finite element simulation and lab experiment. By investigating the structural strength with environmental data, it can be concluded that big-foot rig could be operated at most of China's offshore fields in moderate weather.