Introduction of degradation modeling in qualification of the novel subsea technology

• Published in: Reliability engineering & system safety Vol. 216; p. 107956
• Main Authors: Srivastav, Himanshu, Lundteigen, Mary Ann, Barros, Anne
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.12.2021; Elsevier BV; Elsevier
• Subjects: Actuation; All-electric subsea production system; Control equipment; Control systems; Degradation; Degradation due to demands; Engineering Sciences; Failure analysis; Failure modes; Harmful testing; Hydraulic control; Markov processes; Modelling; Multiphase Markov process; Production controls; Reliability analysis; Reliability engineering; Safety; Safety performance assessment; Safety valves; Springs (elastic); Technology qualification; Time dependence; Upgrading; Valves; Degradation due to demands; Technology qualification; All-electric subsea production system; Safety performance assessment; Multiphase Markov process; Harmful testing; All-electric subsea production system; Degradation due to demands; Harmful testing; Multiphase Markov process; Safety performance assessment; Technology qualification
• ISSN: 0951-8320; 1879-0836
• DOI: 10.1016/j.ress.2021.107956

All-electric systems are the novel subsea technology that is an upgrade of widely deployed electro-hydraulic control systems. They promised more reliable equipment and a safer environment. An all-electric production system performs several functions related to hydrocarbon production control. It also performs safety functions by isolating the reservoir from the environment. Safety functions are performed by activation of safety valves. These safety valves include electric springs in their design instead of mechanical springs. Failure modes and effects analysis of these valves show that interruptions in the power supply appear as random demands to the safety valves, and experiencing such demands may deteriorate their performance. However, the current reliability assessment of safety valves does not consider any degradation phenomena. This paper’s main objective is to investigate the degradation modes caused by demands and their influence on the all-electric actuation system’s performance under different maintenance strategies. A degradation modeling framework based on the multiphase Markov process is proposed. The impact of demand is modeled by changing the initial condition or by increasing the transition rates between two degraded states. The amplitude of the increment depends on the condition at the time of the demand. Analytical formulae are developed for the time-dependent reliability assessment. •Degradation modeling of the safety valves of an all-electric actuation system.•Effect of demands, harmful tests, and various maintenance strategies on degradation process.•A multiphase-Markov-based framework is developed for assess reliability of the safety valves.•Analytical formulae are developed time-dependent unavailability and average unavailability.