Over the past few years a specific programme has focused on the development of subsea separators and a subsea water treatment and injection process composed of several modules and requiring a certain amount of new subsea technology (subsea barrier fluid-less water injection pumps, filters, special water analyzers, etc.). One of these technologies is the all-electric subsea control system. The all-electric versus the electro-hydraulic solution was selected for its inherent capability to:enable long step-out distances;run logics such as sequences and fast closed control loops involving subsea proportional valves;handle high frequency of simultaneous valve actuations;implement safety functions, including SIL certified, when required. Within the ongoing industrialization programme of the new technologies, a Joint Development Agreement has been put in place between two partners for the qualification of the open framework platform for the control of subsea processes. The development is pursued according to the API 17N and DNV RP-A203 requirements. The subsea control system is developed according to the approach to interface standardization, which is aimed at guaranteeing:–the interchangeability of modules coming from different vendors;–the reduction of physical interfaces;–the optimization of IMR intervention time. The technology mainly consists of:a qualified basic component platform to be used for project-based assembly;a complete set of tools such as web-server, condition monitoring server, integrated software development environment, etc.;a standard and user-friendly approach for software application development, based on P&ID graphic, in order to facilitate the sharing of software information between contractor and clients;standard industrial communication protocols (no proprietary protocols) accessible to all users, which are designed for easy interfacing of the control system with third party equipment. The JDA activity has concluded the Q1 qualification tests of electronic components and Q2 tests of electronic assemblies, pursuant to API 17F, as well as all the other qualification activities (tests and analyses) relevant to the non-electronic components (e.g. 40kVA subsea electrical transformer), according to the relevant technology qualification plan. Additional software packages have also been developed and successfully tested using the Test Driven Development (TDD) method. The qualification will be completed by Q1 2019 with integration tests of:–Topside Control System;–Subsea Power and Communication Distribution Manager;–Subsea Control Unit. The integration tests will allow to reach TRL 4 of the above subsea equipment, in accordance with API 17N.
This paper discusses the requirements for a "next-generation" subsea control system and provides a description of the proposed setup/architecture. Requirements for "next-generation" subsea control focuses on requirements for "digitalization" and Industry 4.0 capabilities. Existing subsea control systems today are intended for and used to control hydraulic valves in subsea production setups. The proposed "next-generation" subsea control system is specified, designed and built for an all-electric process control setup, with requirements for extensive usage of digitalization toolboxes. Primary requirements for the "next-generation" subsea control system would be deterministic behavior and latency in the millisecond range for the control of operations part/signals/objects, while at the same time generating large amounts of high quality and highly accurate time-stamped condition monitoring data to be used in the digitalization setup. The proposed concept integrates subsea control and historian systems directly into the existing topsides control and historian systems. Implementation of an anti-surge control system will be used as an example to illustrate the concept for control of operations, and the use of artificial intelligence (AI) and historical stored data would be used as examples for topside digitalization techniques used on subsea installed equipment. Removing boundaries between topsides and subsea automation as suggested in this paper provides options to use already available toolboxes for digitalization of topsides assets on similar subsea components. The proposed open architecture control system would also easily interface directly to any cloud-based solution with standard interfaces or well-defined application program interfaces (APIs). Economic benefits of implementing an open-architecture control system would include CAPEX and OPEX reductions, while at the same time creating a "future-proof" system that allows for the addition of digitalization options. Subsea data would be delivered and stored with higher quality, providing operators with the option to look retrospectively and evaluate historian data based on knowledge to be obtained in the future. Moreover, having one integrated control system provides better protection against cyberthreats, as it eliminates the requirement for several systems, which need to be updated and maintained during the lifetime of the installation. Various predictions and thoughts about the future of subsea controls beyond the proposed "next-generation" subsea control system will also be included in this paper.
Looking at statistics for subsea producing wells in North America, Brazil and Norway the numbers indicate that approximately 50% of these wells were installed before 2005. Most of them rely completely on copper based communication i.e. no fiber optics installed, or at least not used. No Standard communication standard do not exist for neither topside nor subsea in systems installed before 2005 and communication throughput tends to be in the lower range of kilobit pr. second. A large portion of existing wells are experiencing operational problems related to performance degradation in infrastructure and equipment, and are not capable of delivering communication interfaces for upgraded instrumentation and control requirements like multiphase meters, permanent reservoir monitoring and Subsea PowerGrids. This paper looks into solutions for increasing communication throughput while simultaneously mitigating problems due to degeneration of copper cable umbilcals in a cost efficient way. Increased throughput is utilized as expanded connectivity, delivering new standardized communication interfaces both subsea and topside, and at the same time being backwards compatible for already installed subsea equipment. The combination of being backwards compatible with the use of standardized communication interfaces gives extended lifetime for valuable communication infrastructure; umbilicals. Large benefits of the proposed solution are also achieved during upgrading of subsea installed equipment since not all subsea installed units must be upgraded at the same time as the topside-subsea communication link are upgraded. To be able to supply enough electrical power to new subsea units on an existing umbilical already almost fully utilized a transformer based solution are described. For umbilicals with very low IR (Insulation Resistance) values, a transformer setup for lifetime extension of the umbilical are also described.
This paper focuses on the benefits of removing existing control boundaries between subsea system components/parts and the automation setup located topsides on the platform (or onshore). The paper describes the communication architecture of existing subsea control systems used today and proposes a new architecture with boundaries removed. This new setup would utilize the same physical (i.e. fiber-optic) communication channels as present systems. For illustrative purposes, a use case for the proposed system will be presented on an anti-surge setup for a subsea pump/compressor. Existing subsea control systems today are intended for and used to control hydraulic valves in subsea production setups. The design and behavior of these systems make them not optimal for anti-surge control (among other applications). Interfaces and communication protocols used in the proposed use case are based on open industry standards, resulting in a vendor-agnostic system with no proprietary or company-specific solutions, and no boundary between the subsea and topside/onshore located parts. Potential benefits of the proposed system would include reduced latency, along with the combining of several measured values for increased accuracy over a larger scale, illustrated with an anti-surge example. This could enable operators to realize cost savings through optimization and increased production over the life of the installation. As the paper will describe, the system also has the potential to reduce both CAPEX and OPEX.
This paper discusses the requirements for a "next-generation" low power distribution for subsea control systems and provides a description of a proposed new setup/architecture. The future seems to be all-electric for seabed installed equipment, moving away from the usage of hydraulic power to operate valves on the seabed. The increasing usage of subsea drones are another subsea located device consuming electrical power for charging in between active work periods. Location and topology of future subsea field developments has presented the subsea industry with new challenges. Some of these challenges include increases in the step-out length between new subsea installations and existing or new surface facilities, as well as water depth increases. New subsea fields tend to be smaller in size and scattered over a larger area in between the larger already discovered and producing fields. These smaller subsea fields are usually connected to an existing surface located production facility, in a so-called subsea tieback solution. The existing surface setup could have limited physical space available and/or limited amount of potential individual connections for the new subsea installation. In an already existing FPSO (Floating Production Storage and Offloading) installation the swivel could be a bottleneck for future expansions regarding the amount of electrically operated subsea equipment.
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