Effects of Buoy size on the frequency and time response in catenary mooring system of the semi-submersible platform

Due to the depletion of shallow water resources, the development of exploration and production has shifted towards the deep and ultra-deep water region. The types of floating platforms are all need to be moored when they are working as production platforms. Applying buoys to the catenary mooring system in deep water may reduce part of the weight and radius of a mooring. In this article, Dynamic responses of the Amirkabir semi-submersible platform was obtained under the combination of wind and wave loads in frequency domain and time domain simulation calculated. The JONSWAP wave spectrum and API wind spectrum are considered as environmental conditions .and also the effects of buoy size on the semisubmersible motion response is investigated. Dynamic responses of the semi-submersible platform determine by using the Morison equation and diffracting theory in AQWA ANSYS software and each dynamic mooring line is modeled as a chain of Morison-type elements subjected to various external forces. The obtained result from AQWA ANSYS in time and frequency domain shows that increasing buoy size, could increase motions of the semisubmersible platform but instead could decreasing the mooring line tension.