In this thesis, the time-domain analysis of dynamic positioning assisted single point mooring positioning capability of a drilling and oil-production vessel is studied. The vessel has a larger displacement than regular drillship for oil production and is also designed for drill and well repair. Therefore the vessel can be considered as combination of a drillship and FPSO, and three hypothetical positioning systems, the dynamic positioning system, single point mooring positioning system and dynamic positioning assisted single point mooring positioning system are proposed and their capacities at South China Sea are studied. The time-domain analysis of the vessel with three positioning systems is carried out, and the dynamic positioning assisted single point mooring positioning is recommended.
With the development of "shale gas revolution" in the United States, profound changes have taken place in the global energy pattern. The crude oil price has gone very low for a very long time before 2022. Therefore, the exploitation of offshore oil and gas resources has suffered tremendous cost pressure.
The drilling and oil-production vessel is a unit combining two functions of drilling and oil & gas production, which can be used for progressive development of successive oilfields without other drilling units. The vessel can carry out drilling operation meanwhile the oil & gas production does not need to be stopped, which makes incomparable economy performance compared with traditional offshore oil & gas resources exploitation units. Therefore, the drilling and oil-production vessel has become a very important developing equipment in the field of ocean engineering, and the related research is the frontier topic in the offshore industry.
At present, the drilling and oil-production vessel has only been successfully applied in the West African Sea area because of the mild environmental conditions, but its application in the South China Sea area has just started. The main reason is that the environmental conditions in the South China Sea are more complicated and stronger than those in West Africa, with far greater wave height and wind speed than those in West Africa. Also, the dominant environmental factors and dominant direction in the South China Sea change significantly with seasons. It is a severe challenge for positioning capability and development of the vessel.
