This paper performs series of parametric analysis, validated with Abaqus simulation, to establish optimum condition for deepwater drilling riser survivability in freestanding mode. Twelve parametric case studies are carried out on influencing parameters such as buoyancy can upthrust ratio (BCUR), buoyancy can (BC) position, and riser thickness. In the first four cases, results show a suitable BCUR which is used in subsequent cases. Results of the next five and the last three cases gave suitable BC position and thickness respectively. Results obtained from the overall cases are used to establish the optimum condition for survivability of the riser.


A freestanding drilling riser (FSDR) system serves as a means to combat the challenges, such as tediousness, time-consuming, and huge risk of untimely evacuation of personnel and facilities for safety, associated with the conventional practice of retrieving the whole length of drilling riser. Unlike the conventional drilling riser system, a FSDR system has principally additional two features which are the near surface disconnection package (NSDP) and buoyancy can (BC). It is disconnectable at the NSDP with the short riser section removed while the longer riser is supported by upthrust produced from the BC.

The concept and system have been put forward to provide a solution for the disadvantages of retrieving the whole length of drilling riser in the advance of a typhoon environment (Kogure et al., 1998, Bye et al., 2000, Nguyen et al., 2006, Lim et al., 2008, Abimbola et. al., 2020). A field trial of freestanding drilling riser system (Guo et al., 2015) have been introduced. The effect of typhoon generated swell on FSDR has been studied through finite element analysis (Yong et al., 2018). The parametric study has been carried out to understand the FSDR response under typhoon condition (Xu et al., 2019), the mechanical characteristics and operating envelope of FSDR has been studied (Wang and Gao, 2020), and the survivability study of deepwater drilling riser in freestanding mode has been presented (Abimbola et. al., 2021). Static and dynamic analysis of risers under various conditions, mathematical models, and numerical simulations have been put forward regarding the study of risers (Sattamini and Ferranti, 1993; Ju et al., 2011; Wang et al., 2014; Yang and Abimbola, 2022).

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