Experimental investigation on mating operation during float-over installation of a large topside in waves

Abstract

In this study, a series of model tests were carried out to evaluate the mating operation during a float-over installation in waves. Three experimental models, which include a DTV (Deck Transportation Vessel), a topside and a jacket platform, were introduced. There are various interface items such as LMU(Leg Mating Unit)s, DSU(Deck Support Unit)s, fenders, tethers and moorings. The model tests were performed at Ocean Engineering Basin of KRISO. In the test, three mating stages of 10%, 40%, 70% load transfers were considered. Irregular and white noise waves were tested under three different wave headings. Focus is on the dynamic forces acing on the interface items and motion responses of the DTV. The experimental data are directly compared with the numerical simulation results. The mating performances are suggested with respect to the maximum impact forces acting on the LMUs and DSUs. It can be seen that the characteristics of the impact forces are closely related to the motion responses of the DTV. Discussions were made on the effects of wave headings, load transfers and topside center of gravity on the impact forces of LMUs and DSUs. In a fixed offshore structure installed in shallow depths, the topside, including the oil production platform and excavation equipment, is placed on a jacket structure fixed to the sea floor. Copyright ？ 2017 by the International Society of Offshore and Polar Engineers (ISOPE).