The Research On Marine Riser Design Criteria

The Marine riser is a key structure that connects the underwater production system with the floating platform.During the exploitation of offshore oil and gas,the Marine riser should not only meet its own work requirements,but also be subjected to the bad Marine environment and floating motion.So the design of riser is full of challenges.Since there is short of related specification about the riser design in China,the relevant research is needed to be carried out immediately.The differences and similarities among the kinds of foreign standards are analyzed in this paper.The contents are as followings:(1)Some problems,such as application area,ultimate state,working condition definition,design method,strength checking and other contents of DNV,API and ABS are compared and analyzed in this paper.(2)Ten vertical pipe cases are calculated and compared with the results of different specifications.The results are verified from the perspective of reliability calculation.(3)Combined load checking criteria is analyzed in the riser specification.At the same time,several vertical pipe cases and the utilization coefficients of different specifications under different conditions are calculated.The requirements of each specification are also compared.(4)Several problems in reliability calculation are studied in this paper,including performance function,probabilistic characteristics of random variables and random processes,load conversion,and corresponding uncertain random variables.At the same time,an improved second order moment(FORM)method is used to calculate the dynamic reliability of the Rises.(5)By means of probability analysis,the resistance and load factor coefficients results of the target reliability are obtained,and the criteria for the assessment of vertical pipe strength under combined loads are established.