The Research Of S-Lay Method For Steel Catenary Risers

At the present, J-lay and S-lay are main methods used in the installation of steel catenary risers(SCR) in deepwater. The S-lay method is developed rapidly from shallow water to deep water for its high weld quality and lay speed. So the S-lay analysis of SCR is done in this paper by Orcaflex software which is applied wildly to analyse the strength,fatigue and installation of pipelines. The main contents and issure of this paper are as follow:(1) The main installation methods of SCR are introduced and the information,such as installation method,water depth ect, of real installation experience is concluded(2) The S-lay method is analysed with different conditions and the characteristics of risers in different stiger parameter,water depths and riser contents are discussed;(3) The influence coming with different riser contents are discussed in detail. In order to make the advantage of two installation states (flooded installed and empty installed) to the greatest degree, the partial flooded installed method is developped and analysed in this paper.(4) The conclusion summarized from the parper are as follow:(a) the reaction force between the riser and stinger is increasing with deeper water;(b) in order to avoid the stress/strain jump at the end section of stinger, the tension must be controlled to make the lift-off point of riser away from the stinger end point when the horizonal launch angle of stinger is small;(c) when the stinger is not suitable to use, the stinger length will be adjusted first rather than the launch angle which is larger enough;(d) the first roller reaction and the lift-off point roller reaction are more serious than the others, generally; (e) thinner riser thickness can be chosen that will cut the cost in a certain degree, and the stinger will be used more wildly(deeper water ect.) when the partial installed method is adopted.The innovations presented in this paper are: (i) the interaction between rollers of stinger and riser are modelled by linkers which can simulate the loading on risers well and be in agreement with the fact. (ii) the differences coming with the varying riser inner contents are shown. (iii) the partial flooded installed method is developped and analysed in this paper to avoid the disadvantage coming by empty installed and full flooded installed methods.