Floating non-traditional manufacture of floating drilling storage and offloading units—study on modeling and optimization method for the underwater rotating technology

The purpose of this study is to find proper modeling and optimization method for the underwater rotating technology used in floating non-traditional manufacture of FPSOs. The underwater rotating technology includes the block division in the FPSO bottom and the underwater rotating angle of the uncompleted bottom. The model contains many practical requirements, such as the size of the semi-submersible barge, the area required for drilling oil and gas, the mass of the unit area in the FPSO bottom, the lifting capacity of the factory and the operation space for workers. The model of the underwater technology in the paper would first minimize the number of the rings in the bottom, second minimize the number of the block in each ring, and finally find the maximum underwater rotating angle. The Sevan Driller FDSO manufactured by COSCO (Nantong) Shipyard Co., Ltd in China is employed as number examples in the paper, and the results show the model proposed in the paper is correct and valid, which could provide a theoretical basis for the promotion of floating non-traditional manufacture.

► We propose floating non-traditional manufacture (FNTM) of FPSOs.
► We model the underwater rotating technology used in FNTM.
► The first part of the model is the block division in the bottom.
► The second part of the model is the underwater rotating angle.
► The model is successfully applied to Seven Driller FDSO.