Frames Flow Control & Safeguarding creates fully autonomous wellsite skids thanks to PlantPAx DCS


Leading oil and gas equipment supplier develops fully integrated process and safety solution on single solar-powered skid

The Frames Group describes itself as providing the vital link between the well and the pipeline in the international oil and gas industry. It designs, builds and delivers separation technology, oil and gas treatment, flow control and safeguarding systems and modules and integrated solutions, such as total plants, working directly with its customers to optimise upstream, onshore and offshore processes.

Headquartered in Alphen aan den Rijn in The Netherlands, Frames has more than 500 employees working in offices worldwide and comprises six strategic business units, each focused on a specific range of systems & solutions.

Frames Flow Control & Safeguarding is playing a vital role at the Nawara oil field in Tunisia, for which it designed, assembled and installed nine fully autonomous well-site skids, which offer both process control and a comprehensive safety system near the head of each well.

For the Integrated Control and Safety Solution on the skids, Frames opted for the Rockwell Automation® PlantPAx® distributed control system (DCS) in conjunction with its distributed and scalable AADvance® control system for the process safety solution. The AADvance application was created in collaboration with a Rockwell Automation Global Process Technical Consultant and solution architects, who advised on development and system configuration.

The skids may be located in the vicinity of the well sites, but they are some distance from the central processing facility (CPF) to which they feed not just the gas – for separation into condensate and dew-pointed gas – but also a myriad of control signals and production and safety data that help maintain optimum operation of each of the well sites.

The control system on the well-site skids needs to be able to monitor and activate all of the various valves on the ‘Christmas tree’ (an assembly of pipes, valves, spools and fittings) at the head of the wells. It subsequently communicates with a remote terminal unit (RTU), which then forwards any signals to a DCS at the CPF.

Due to the remote nature of this installation and the requirement for an integrated control and safety solution, Frames needed to deploy an industry-proven solution that would not only operate effectively out in the field with minimal operator interaction, but would also address the demanding performance criteria laid down by the international oil and gas industry.

Strict lead times and the large variety of third-party systems deployed on the well-sites also added complexity to the project and additional challenges to the control and safety solution.

The skids supplied by Frames are, due to their remote location, solar-powered and autonomous, providing wellhead control panels, chemical injection systems, flowlines through which the gas is transferred and choke valves that are used to regulate the flow. The control system is divided into the basic process control system (BPCS) and safety (SIS).

The PlantPAx DCS chosen by Frames for the Nawara project seamlessly integrates safety with critical process control to help protect all assets and personnel. Based on more than 40 years of expertise in safety and critical control solutions for the oil and gas industry, PlantPAx offers a solution for multiple oil and gas applications, including subsea, ESD, F&G, Turbine and Compressor, Blow Out Preventers, HIPPS, Combustion Control and CPC solutions.

For the BPCS (process control) elements of the skids, Frames deployed a Rockwell Automation solution – comprising multiple ATEX-certified products and components – and implemented a scalable PlantPAx DCS in conjunction with I/O modules. Primary control and monitoring is provided by a Panel PC, with multiple dedicated high-end HMIs running PlantPAx Operator Workstations (OWS) that delivers an operator interface with advanced diagnostics and process faceplates for pumps, valves, etc. Communication is via a Layer-2 managed Ethernet switch.

To address the safety demands and for seamless integration into the PlantPAx environment, Frames utilised AADvance programmable safety controllers to fully take care of the emergency shut down (ESD) system, which is installed on the skid. A truly distributed, scalable architecture, AADvance comprises both a hardware controller and a software environment, allowing users to specify the level of safety integrity and availability needed throughout their application.

A key feature of the AADvance system is its versatility with respect to size, safety and availability. AADvance provides an effective solution, whether the I/O count is small or large. AADvance suits non-safety applications, as well as protective systems, whether failsafe normally de-energized. Architecture is flexible, ranging from simplex, for non-critical applications, to triplicated, where very high availability is essential. AADvance is certified for safety applications up to SIL 3 and is an integral part of the Rockwell Automation PlantPAx integrated control system.

According to Dwayne de Wit, Project Engineer for the Nawara project at Frames Flow Control & Safeguarding: “The main reason why there is the need for a comprehensive safety solution on the skid is due to several ESD scenarios, which are instigated after a dedicated button is activated on the skid. When the ESD button (installed on the control cabinet) is pressed, the ‘Christmas tree’ valves have to shut down in a certain sequence to prevent over pressurisation and other potentially dangerous scenarios.

“The AADvance controllers in this application,” he continues, “are SIL 2 certified with redundant CPUs and simplex I/Os. They communicate using hardwires to the third-party ESD system, which communicates over standard EtherNet/IP™ to the PlantPAx controller using a redundant Ethernet port embedded on the AADvance system.”

“We chose Rockwell Automation due to its common understanding of industry practices and the existing relationship we have,” de Wit explains. “The major advantage of this solution is that it combines several technologies – which would normally have been split over several skids – into one compact integrated skid. As well as addressing ‘real-estate’ issues, this also has significant cost-saving implications.

“It was the Rockwell Automation PlantPAx DCS and Library of Process Objects that not only made programing far easier,” he continues, “but also provided us with the necessary means to make the skids autonomous. Coupled to the hardware, support and programming, the skids can actually upgrade themselves out in the field.

“The integrated control and safety system from Rockwell Automation for both basic process control and comprehensive safety system work really well together,” de Wit elaborates, “and make installation easier. Indeed the wellsite skids are effectively plug-and-play. You simply install the skid, connect the flow line, make sure the communications are in place with the DCS and control system and they just run.

“We did initially speak with other suppliers during the bid stage,” de Wit concludes, “but very soon found out that from the start Rockwell Automation offered exactly what we needed. Couple this to our previous experiences and common understanding, combined with the knowledge at Rockwell Automation and we were confident that we had a system that was fully optimised for this type of application!”

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