With the exploration and development of offshore oil fields, the offshore oil industry has developed rapidly. The offshore operation platform is developing in the direction of large-scale and intensive, and the overall weight of the offshore platform topside structure also increases. The rapid development of offshore oil and gas field development has put forward higher requirements for the installation technology and operation capability of offshore super large platforms. The traditional installation method of offshore platforms is facing unprecedented challenges, which has restricted the rapid development of China's marine resources exploration and exploitation.
The installation of traditional offshore structures mainly includes self installation and hoisting.
Self installation It means that the platform does not need to borrow external resources and equipment, but is installed in place in the predetermined sea area relying on its own equipment capacity. For example, China National Offshore Oil Corporation (hereinafter referred to as CNOOC) Bozhong 3-2 jack up production and storage platform, which uses its own pile legs and lifting devices to lift the ship to meet the operating requirements. This method does not need to borrow scarce resources such as floating cranes, and saves the installation cost of the platform. However, this method is greatly limited by water depth and oilfield productivity, and is suitable for small shallow water oilfields. Therefore, it is difficult for self installing platforms to be widely applied in deeper waters.
hoisting It is also divided into block hoisting and integral hoisting.
Block hoisting: divide the upper structure of the platform into several blocks and hoist them to the lower foundation for welding and fixation. The large platform module with a weight of nearly 10000 tons usually needs to be divided into five or six sub modules, which are built separately on land and hoisted and spliced separately on the sea. Due to the various interfaces and complex interfaces between the blocks, this kind of installation brings great inconvenience to the design, construction, connection and commissioning of the blocks, and the installation operation takes a long time. Generally, the offshore operation time of 10000 ton module lifting and installation is up to one and a half months, and the offshore commissioning time exceeds three months. The installation investment is huge and the production progress is affected.
The overall lifting requires the use of a large crane barge to lift the topside as a whole onto the substructure of the platform for welding and installation. Due to the limitations of floating crane's lifting capacity, structural strength and size of structures, the number of giant crane ships (few), operating costs and other factors, this method is difficult and costly to install large platform modules, and cannot be used for the overall lifting of super large modules. At present, the static lifting capacity of the world's largest crane ship is 14200 tons, and there are only two ships above 10000 tons, which are owned by foreign companies and operate abroad.
To accelerate the development of offshore oil, it is necessary to change the traditional oil field development mode and find a more economical and faster development plan. Therefore, the floating installation technology came into being, which is the best solution for the overall installation of 10000 ton module.
