Title Position-moored drilling vessel in level ice by control of riser end angles
Author Nguyen, D.H.; Nguyen, D.T.; Quek, S.T.; Sorensen, A.J.
Author Affil Nguyen, D.H., National University of Singapore, Department of Civil Engineering, Singapore, Singapore. Other: Marine Cybernetics, Norway; Norwegian University of Science and Technology, Norway
Source Cold Regions Science and Technology, 66(2-3), p.65-74, . Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0165- 232X
Publication Date May 2011
Notes In English. Based on Publisher- supplied data GeoRef Acc. No: 309726
Index Terms anchors; drilling; loading; models; piers; simulation; stability; stresses; thickness; controls; level ice; marine installations; stress
Abstract This paper focuses on the control of marine riser of a position-moored drilling vessel operating under level ice regime with different ice thicknesses. The strategy is to ensure that the riser end angles (REAs) are within the safe limits for drilling and work- over operations by keeping the vessel at an appropriate position. Using a control criterion based on REAs, the desired vessel position is computed to counteract the environmental disturbances. An optimal set- point chasing algorithm is used to control the mooring lines by adjusting their lengths to bring the vessel to the desired position. The ice load model of Nguyen et al. (2009) was used to simulate the vessel-ice interaction. Numerical simulation results of a moored drilling vessel first exposed to open water and then to level ice of different thicknesses indicated that the proposed control strategy performs satisfactorily in level ice regime. The riser end angles and bending stresses along the riser are reduced considerably when in automatic control mode.
URL http://hdl.handle.net/10.1016/j.coldregions.2011.01.007
Publication Type journal article
Record ID 65006375