This paper presents the rational analysis method and its successful application in the floatover installation of the JZ9–3 topsides for a central production platform in a water depth of 8.9 meters in China Bohai Bay. Some limited model test results are available for a comparison. A parametric sensitivity study was performed with variations of different barge drafts, different wave direction, etc.This parametric study is conducted to investigate the shallow water effect.This comparative study not only ensures the integrity of the shallow exit analysis, but also benefits safe floatover operations by calibrating the numerical modeling of the T-shaped barge in the floatover simulations of future topside installations.
The JZ9–3 Oil Field is located in the northern of Bohai Liaodong Bay, the People's Republic of China, with east longitude of 121°24' ∼121°37' and north latitude of 40°37' ∼40°42'. JZ9–3 Oil Field infill development project is an upgrading project to existing installed facilities. The CEPD platform, as a key part of the overall JZ9–3 Oil Field infill development, is a combined drilling and production platform with 24 well slots, and was successfully installed on Sep 16, 2014.
A T-shaped launch barge was successfully used with a high-deck floatover scheme to install 10,500Te integrated topsides onto a preinstalled jacket standing at a water depth of 8.9 meters in JZ9–3 Oil Field. Nonlinear time-domain simulations were performed to investigate the three typical installation stages including docking and undocking operations at three different entry and exit positions, as well as various stages of the mating process. A parametric sensitivity study was performed with variations of different barge drafts, different wave direction, etc.
This paper describes the nonlinear simulations of this challenging floatover installation performed to analyze rubber material nonlinearity, fender geometric nonlinearity, and complex contact mechanics during docking, mating, undocking operations, as well as hydrodynamic effects of the T-shaped floatover barge. Refer to He et al. (2011) for details. A linear diffraction analysis is conducted in frequency domain by using WADAM to calculate the first-order motions, wave drift forces, as well as hydrodynamic characteristics of the T-shaped barge, thus generating hydrodynamic database for the nonlinear time-domain simulations. The SESAM family software SIMO is then used for the nonlinear time-domain simulations to extract the impact loads and motion time series for the selected sea states. Various coupling elements are applied to simulate the nonlinear contact mechanics, including two sway fenders, two jacket entry guides, two surge fenders/longitudinal stoppers, 8 leg mating units (LMUs), 8 deck support units (DSUs), etc. The numerical findings of the time-domain simulations are used to properly define the limiting environmental conditions, the dynamic behavior of the floatover barge, the movement of mating cones, as well as guide the design of LMUs, DSUs, the fender system, the gap between fenders and jacket legs, etc.
