No abstract

At present, offshore drilling operations often use buttress thread casing as surface casing. The design conception of buttress thread casing comes from the offshore drilling’s demands and this kind of casing is mainly used as surface casing. This paper has taken material mechanical experiment, numerical simulation analysis and field test, the research results show that the various parameters of buttress thread casing fully complies with the drilling design requirements and the offshore oilfield production demands. This product can reduce drilling cost effectively, improve working efficiency and safety, and realize manufacture domestically. Meanwhile, the development of this project will fill the blank of the ERW (Electrical Resistance Weld) casing in CNOOC (China National Offshore Oil Corporation), and have a broad prospect of application.

Both the method of engineering and nonlinear finite element method have been used to the analysis and optimum design of the 30 in. marine riser with the screw thread. Two load steps have been used in the finite element analysis including the processes of both assembling and applying the load of piling, and the nonlinear contact between marine risers has been considered in the simulation. Numerical results show that the stress in the marine riser increase rapidly when the magnitude of interference of the screw thread change slightly. By the way to change interferential magnitude of the screw thread, the maximum stress of Von Mises decrease from 681MPa to 381MPa and contact stress decrease from 238MPa to 122MPa. The engineering practice over 100 piles in offshore platform has shown that the numerical results are good.