Collision Risk Analysis In FPSO Tandem Offloading Operation

In the 21 first centuary,people started putting their eyes on the field of ocean pretroleum exploitation,and all kinds of ocean oil drilling platforms have thus been well developed.FPSO(Floating Production Storage and Offloading)is the primary focus in all the platforms due to the advantages of adapation of wide range water depth,strong resistance to enviromnental forces,etc.A shuttle tanker is needed to carry the oil to the shore after oil offloading from the FPSO.During process of oil offloading operation,there might be occurance of some risk accidents,and the most typical one is collision.FPSO-Shutter collision accidents were evaluated with quantitive and semi-quantitive methods in this thesis with a FPSO and a shuttle tanker operating on the sea being selected as research objects.Based on extensive literatures review,an FPSO-shuttle tandem offloading collision assessment index system was established and mutiple methods such as Emperial Formula,Extreme-type Theory,Grey Clustering,Fuzzy Logics and Fuzzy Bayesias were used to carry out the evaluation,and the risk reduction measures were also suggested.The main contents of this paper are as follows:(1)Emperial formula was used to calculate the probabilities of dynamic collision and drifting collision for the FPSO-Shuttle tanker system;then the three-dimension model of FPSO and a shuttle Tanker was established in CATIA and exported to AQWA for simulation in different loading conditions and operating conditions.The data obtained was used to conduct the extreme type I distribution assessment and thus the probability of relative excessive surging movements was calculated for the comparison of the previous probability results.(2)A group of risk factors were seleted from the established risk index system and a semi-quantitive assessment was conducted based on the grey clustering method in combination with Analytic Hiararchy Process.The collision risk level was reached and risk input factors that influence the risk level most was also located by sensitive analysis.(3)Another semi-quantitive assessment was performed based on fuzzy logics.There exists a cosistency between the result and that reached by the previous method.(4)Fuzzy Bayesias method was employed to carry out the collision posterior possibilities relied on the input factors.It was found out that the misconduct of the supporting vessels has a great impact on collision.Then the empirical formula was used to calculate the probability of collision led by supporting vessel misconducts,thus the soundness of the Fuzzy Bayesias method.A risk evaluation management system was proposed to lower the risk level,which can be applied in the established risk assessment system in this thesis.The research results and conclusions provide reference for the real-case FPSO-Shutter tanker operation and guidance for the personnel working on site.