Submit your papersSubmit Now
For Enquiries: [email protected]
IIARD LogoIIARD

Distribution-free Survival Analysis for Reliability Evaluation of Subsea Distribution Units

Ezebuchi Akandu, Godstime U Ugwulashi

Abstract

Subsea Distribution Units (SDUs) are critical components in offshore production systems, responsible for routing hydraulic, chemical, and electrical services to subsea wells. Failures in SDUs cause costly downtime, complex interventions, and safety/environmental risks. Reliability analysis is often hindered by limited and censored failure data, making parametric lifetime models unreliable. This study applies distribution-free survival analysis using the Kaplan–Meier estimator and Nelson–Aalen cumulative hazard method to evaluate SDU component reliability. Survival curves, hazard functions, and failure rankings are generated for major subsystems based on operational field data (41,902 units, 392 failures). Results highlight Power/Signal Couplers and Hydraulic/Chemical Jumpers as the most failure-prone subsystems, with elevated cumulative hazards. This work demonstrates the value of non-parametric survival methods for offshore reliability studies where distributional assumptions are uncertain.

Keywords

Subsea Distribution Unit (SDU)Kaplan–MeierNelson–AalenReliabilitySurvival

References

Abdelaty, I. F. (2024). Technology focus: Reliability challenges in subsea control systems. Journal of Petroleum Technology Bureau of Safety and Environmental Enforcement. (2019). Well control rule and deepwater operations. Washington, DC: U.S. Department of the Interior. Cordes, E. E., Jones, D. O. B., Schlacher, T. A., Amon, D. J., Bernardino, A. F., Brooke, S., … Young, C. M. (2016). Environmental impacts of the deep-water oil and gas industry: A review to guide management strategies. Frontiers in Environmental Science, 4(58), 1–26. https://doi.org/10.3389/fenvs.2016.00058 Kaplan, E. L., & Meier, P. (1958). Nonparametric estimation from incomplete observations. Journal of the American Statistical Association, 53(282), 457–481. Li, X., Chen, Y., Ren, Z., & Wang, J. (2024). Advances in flow assurance for subsea production systems. Journal of Natural Gas Science and Engineering, 120, https://doi.org/10.1016/j.jngse.2023.104239 Mahmoudi, A., Gao, Y., & Wang, J. (2021). Integrity and reliability assessment of subsea pipelines and umbilicals under harsh environments. Ocean Engineering, 239, 109830. https://doi.org/10.1016/j.oceaneng.2021.109830 MDPI (2024). Reliability-based preventive maintenance strategy for subsea control systems. Processes, 12(4), 761. Nelson, W. (1972). Theory and applications of hazard plotting for censored failure data. Technometrics, 14(4), 945–966. OREDA. (2015). Offshore Reliability Data Handbook (6th ed.). SINTEF. Rao, R. S., Naikan, V. N. A., & Reddy, Y. V. (2015). Comparison of reliability techniques of parametric and nonparametric methods. Engineering Science and Technology, 18(3), 412– Yasseri, S. F., & Bahai, H. (2018). Availability assessment of subsea distribution systems at the architectural level. Ocean Engineering, 151, 206–215.

More Articles from INTERNATIONAL JOURNAL OF ENGINEERING AND MODERN TECHNOLOGY