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Schlumberger announced an award to OneSubsea by A/S Norske Shell of a frame agreement for an engineering, procurement, construction, and installation (EPCI) contract for the supply of a subsea multiphase compression system for the Ormen Lange Field in the Norwegian Sea. Through the EPCI contract, OneSubsea, the subsea technologies, production, and processing systems division of Schlumberger, and its Subsea Integration Alliance partner Subsea 7 will supply and install a subsea multiphase compression system that uses the industry's only subsea multiphase compression technology. OneSubsea will, in the first phase of the project, do the engineering and design of the complete system. Following the final investment decision by the license group, the complete scope of the EPCI will be executed. The compression system will be powered and controlled from the Nyhamna onshore gas processing plant, which is 120 km from the subsea location.
Kim, H. (Norwegian University of Science and Technology) | Lundteigen, M. A. (Norwegian University of Science and Technology) | Hafver, A. (DNV-GL, Oslo) | Pedersen, F. B. (DNV-GL, Oslo) | Skofteland, G. (Statoil)
Systems-Theoretic Process Analysis (STPA) is a recently developed hazard identification technique that is based on control and systems theory. Previous studies on STPA emphasize two major strengths of the method: (1) STPA provides a systematic top-down approach that enables early identification of system flaws, and (2) STPA covers a wider scope of hazards compared to traditional methods. Despite these advantages, there are only a limited number of studies that have applied the method to subsea systems. It is therefore of interest to investigate how STPA can be used to formulate new or verify existing requirements to safety-critical systems for subsea facilities. One example is the isolation of subsea wells initiated by the platform emergency shutdown (ESD) system. The purpose of this paper is to apply STPA to this function, and to discuss opportunities, challenges and possible implications of the results obtained from the analysis.
The paper starts with a thorough literature study and includes an analysis of the insights and recommendations made from other industry sectors and application areas. This review is followed by the STPA analysis of the proposed system, with focus on the identification of the unsafe control actions and safety constraints for subsea well isolation. It is investigated how STPA is able to address specific design philosophies and subsea operating conditions, like fail-safe function of subsea ESD valves, long distance between top-side control system and subsea valves, and dynamic behavior of the control structure. The paper concludes with discussions and suggestions on how the STPA procedure may be improved for application to subsea systems.
The use of batteries subsea has historically been limited to powering autonomous instrumentation for oceanographic applications with power capacities typically limited to less than a few hundred watt-hours. Over the past decade, engineering design and technology advances in subsea applications have led to an increased focus on battery technology, including increased capacity. In particular, the growth of the autonomous underwater vehicle (AUV) market in the early 2000's lead to regular use of batteries subsea with capacities of up to tens of kilowatt-hours (kWhr).
In order to enhance production and maximize reliability of offshore fields, focus has increased on placing traditional terrestrial equipment subsea and incorporating electrically powered process equipment. Some of these applications have led to the deployment of large battery and UPS modules for subsea deployment. Notable applications include the recent development of 165kWhr battery modules for the Marine Well Containment Company (MWCC) to allow subsea pumping of dispersant from bladder fields to an uncontrolled hydrocarbon leak, and uninterruptible power supplies that have been marinized for holdup of critical equipment on compressors being qualified now for installation on the Ormen Lange oilfield.
This paper focuses on a concept system being developed and qualified for military applications, similar to the MWCC battery system. The focus is on a marinized pressure compensated battery module of 150kWhr, which can be daisy-chained or arranged in a hub configuration for up to 1.5MWhr of holdup capacity. This paper details original analysis on the application of these battery power modules to provide a UPS for dedicated use with magnetic levitating bearings common on subsea compressors and motors on subsea production systems. By providing a localized UPS system to the magnetic levitating bearing controllers, it is possible to provide a redundant power source, mitigating risk from failure of the primary subsea power supply. Coast down times for the magnetic bearings typically take just a few minutes and fit well within the voltage, current, and power supply levels of the UPS design described in this paper. The distributed UPS system design discussed herein utilizes a modular design. The modules discussed can be configured to allow for expansion and enhanced redundancy to be integrated subsea without the need for a unique qualification program.
This paper discusses potential applications of the UPS within subsea production equipment, including interface points, recovery, discharging, charging, and monitoring.
Subsea processing is an enabling technology for deepwater-oilfield development. The primary technologies of interest are fluid separation and pumping. Subsea processing is a significant technology that presents and will continue to bring many challenges and opportunities to the industry. Can we safely and economically move traditional field-processing equipment from the surface to the ocean floor? There is a strong incentive to eliminate (or greatly reduce the size of) surface-supported processing facilities; they are expensive and heavy, they can certainly be the long-lead item on a schedule, and they are susceptible to environmental (weather) effects that will affect operations.
Most baby-boomers have some familiarity with the classical stigma surrounding aluminum conductors in residential and commercial applications: fire hazard. Mention aluminum wiring in a building or residence and, not surprisingly, a lot of folks will react as if the structure in question should be condemned. How did aluminum get this reputation? Was it deserved? Is it still a valid assumption with today's modern aluminum alloys?
Many of the historical stigmas associated with aluminum can be attributed to technical design problems of the older alloys that have now been overcome by higher quality materials and/or addressed by aluminum specific design considerations. This paper addresses the aforementioned issues and investigates the current status of aluminum conductor technology as applied to subsea power cables with a specific emphasis on the following:
The Element Aluminum;
Early History of Aluminum;
Aluminum (Al) versus Copper (Cu);
Aluminum Subsea Cable Experience.