Search Results (5)

To bridge the gap in the research on the control and drive methods of the key equipment of the new subsea production control system, all-electric subsea gate valve actuator, and to solve the problems of the valve control and drive system in the traditional subsea production system, this paper proposed a full-featured and feasible electrical system of the all-electric subsea gate valve actuator containing the control system and the drive system. The key functions were realized, including status monitoring, redundant communication, redundant power supply, redundant drive, and low-power open-position holding. The electrical system is suitable for monitoring and controlling all-electric subsea gate valve actuators with various specifications and is highly integrated, open, efficient, and real-time. The electrical system prototype was developed and successfully tested for several functions. The results showed that the all-electric subsea gate valve actuator electrical system was capable of controlling and driving the actuator, monitoring the status information of the internal and external environment of the system, as well as the power output information of the drive system, and having redundancy features. Full article

Subsea oil and gas (O&G) exploration demands significantly high power to supply the electrical loads for extraction and pumping of the oil and gas. The energy demand is usually met by fossil fuel combustion-based platform generation, which releases a substantial volume of greenhouse gases including carbon dioxide (CO₂) and methane into the atmosphere. The severity of the resulting adverse environmental impact has increased the focus on more sustainable and environment-friendly power processing for deepwater O&G production. The most feasible way toward sustainable power processing lies in the complete electrification of subsea systems. This paper aims to dive deep into the technology trends that enable an all-electric subsea grid and the real-world challenges that hinder the proliferation of these technologies. Two main enabling technologies are the transmission of electrical power from the onshore electrical grid to the subsea petroleum installations or the integration of offshore renewable energy sources to form a microgrid to power the platform-based and subsea loads. This paper reviews the feasible power generation sources for interconnection with subsea oil installations. Next, this interconnection’s possible power transmission and distribution architectures are presented, including auxiliary power processing systems like subsea electric heating. As the electrical fault is one of the major challenges for DC systems, the fault protection topologies for the subsea HVDC architectures are also reviewed. A brief discussion and comparison of the reviewed technologies are presented. Finally, the critical findings are summarized in the conclusion section. Full article

Underwater pressure-bearing structures are produced in practice by means of pressure self-enhancement methods in order to improve the stress distribution and enhance the pressure-bearing performance. On the other hand, the pairs equation shows that stress is an important factor influencing the degradation of the structure. In fact, improving the stress distribution will not only improve the pressure-bearing performance, but will have an impact on the life degradation trend. Thus, pressure self-enhancement affects the structural life by changing the stress distribution. With this in mind, this paper considers the effect of pressure self-enhancement on the service time of subsea structures, and a Bayesian network (BN)-based method that can be used to predict the remaining useful life (RUL) of underwater self-enhanced structures is proposed. The method also takes into account the influence of multiple sources of structural factors in order to predict the RUL of the structure more accurately. The life degradation process of an all-electric Christmas tree valve actuator is used as a case study. The prediction results are compared with data in the literature to verify the validity of the method. The results have implications for guidance on the O&M assurance of underwater production systems. Full article

To bridge the gap that exists in the key equipment of the new subsea production control system, the all-electric subsea gate valve actuator, and exploit subsea oil and gas resources with high reliability and safety while saving energy, this paper proposes a novel concept prototype of an all-electric subsea gate valve actuator which has the key functions of a redundant drive, failsafe closing, auxiliary override, position indication, and low-power position holding. It satisfied the electrically-driven requirements of the subsea gate valves and achieved Safety Integrity Level 3. The prototype was developed and tested successfully. The all-electric subsea gate valve actuator is suitable for controlling subsea gate valves with various sizes and rated working pressures to minimize the power consumption for the purpose of keeping the valves open and safely closing them in the event of the electrical failure. An override and position-indicating mechanism is equipped for emergency operation and the visual indication of the status of subsea gate valves. Full article

The all-electric subsea gate valve actuator is one of the critical components of the all-electric subsea production control system. To bridge the gap of the low-power holding mechanism in the all-electric subsea gate valve actuator of the subsea production system, minimize the power consumption and cable number for control and improve the open-position keeping performance of all-electric subsea gate valve actuator, this paper proposed a novel low-power holding mechanism for the all-electric subsea gate valve actuator which can be applied to all-electric subsea gate valve actuators with various valve sizes and process pressure ratings. The proposed low-power holding mechanism uses an electromagnet as a driving element, combines the spiral transmission and the cam-like transmission, and only requires a holding force of approximately 2–7% of the maximum load of the closing spring to keep the valve open. The proposed low-power holding mechanism converts the axial force of the closing spring into the circumferential force, which substantially reduces the output force required for the driving element of the low-power holding mechanism and the number of the actuator’s control cables. Analytic models are created for the lockable maximum load of the closing spring and the permissible stroke of the locking tab with regard to the design variables. The parameter effects and the corresponding sensitivities are discussed by numerical analysis. The design parameters and the lockable maximum load of the closing spring of the low-power holding mechanism are obtained. Full article