A traditional multi-leg jack-up can become uneconomical because of increasing water depth and risky due to leg punch-through in very soft foundation. To overcome these difficulties, a novel jack-up concept is introduced. A Mono Column Platform (MCP), is a multipurpose, mat- supported jack-up with only one Leg (Column Structure). To predict the structural behavior of the first MCP unit in extreme environmental condition and in operating condition, a global in-place analysis is performed through finite element analysis. Design specifications are established and detailed models are built to evaluate the unit's structural responses. Static/dynamic structural analysis and overturning stability analysis are performed. Structural responses obtained by static and dynamic methodologies are compared. The results suggest that it is insufficient to only perform static structural analysis under the dynamic environmental loadings, and dynamic response analysis with computational efficiency and accuracy is necessary. The structural integrity of the column structure is verified through code checks and the adequate safety margin is observed. The results of this study provide useful information for the design of the MCP family.
Jack-up drilling rigs are widely used in offshore oil and gas exploration industry. It is originally designed for use in shallow waters; there is growing demand for their use in deeper water depth and harsher environmental conditions. However, a traditional jack-up design can become uneconomical in these conditions. A typical multi-truss-leg jack-up is fitted with 9-16 jacking units and the legs themselves become a major source of steel consumption, meanwhile, positioning the legs at the corner of the deck inevitably reduces the effective usable deck area, hence some of the equipment may have to be installed inside the hull, which creates a congested working environment and difficult accessible spaces. A traditional jack-up is known for its ability to find oil, however, to produce it, a fixed platform is required to be designed, fabricated, transport and installed according to the specific field environment, which takes a long time with high-rise costs before the production of the first oil. Moreover, with spudcan mounted at the legs' bottom, the application of multiple leg jack-up in regions with soft seabed can be challenging due to potential risks of punch through effect.
