Once you've found the best way to execute a project, it only makes sense to replicate those best practices the next time you do a similar project. Such is the reasoning behind a modular engineering methodology that Shell and Yokogawa developed for executing and delivering the automation and integration of subsea control systems, according to Shell's Zara Karkan, who described the joint effort at this week's Yokogawa User Group meeting in New Orleans.

The scope of the development effort included the master control station (MCS) and its integration with subsea control modules (SCM), topside processing units (TPU) and electrical power units (EPU). The MCS, based on Yokogawa's Centum VP automation platform, provides essential HMI and automation functionality for a set of subsea wells communicating with the SCM and instrumentation, such as pressure transmitters, temperature transmitters and sand detectors.

Motivation for the project included a desire by the Shell subsea control engineering group's internal customers to reduce programming and testing time. Standard templates across the company's global operations also were desired to enable easy transfer of operator experience from one subsea field to another. Other deliverables included alarm rationalization, as well as simpler troubleshooting and management of change (MoC) procedures.

Toward One Best Way

"The goal was to create a Subsea MCS Toolkit Design based on Yokogawa's subsea offering and relevant industry standards, such as ISO 13628-6," Karkan said. "We took advantage of advances in alarm management, subsea vendor technologies and other Yokogawa features."

To get things started, two design review workshops were conducted in March and August of 2011, including representation from various Shell stakeholders and from the subsea system vendor. The toolkit would need to comply with the Shell MAC Toolkit and include a proof-of-concept test to demonstrate Yokogawa-TPU connectivity and unit block functions, Karkan said. "But we also needed to review customer opinions and changing requirements."

In the end, the Subsea MCS Toolkit designated "one unit procedure for multiple wells," Karkan explained. A Subsea Unit Block, created in a control drawing and registered as a Centum Smart-Part, includes linked information. "This improved engineering efficiency and enhanced reliability because the parts are all tested and validated."

Efficiencies Delivered

"Engineering is now done in a single system. The toolkit uses generic templates, Smart-Parts and Link-Parts. Wells can be replicated easily, and programming expertise is not needed. The HMI and alarm philosophy can be the same for both topsides and subsea [units]," Karkan said. "Remote system access is now possible, and we have better quality, increased efficiency, more cost-effectiveness and safety."

"Generic programming, once tested for one well, can be easily proven for other wells, with one generic program applicable for all wells," she said. "Any modification or addition can be done once and applied to all wells. All of this saves time and effort, and provides improved quality. There's no necessity for expertise on multiple systems either. We found that we could reduce FAT time from six months on average to one month."

"We only have a single system to upgrade," she said. "In a standard system, renaming or renumbering a well can be a huge change, but in the new system, well addition or renumbering requires just a generic change resulting in significantly less engineering time and facility downtime."

Karkan added, "What we have accomplished is application standardization for control and monitoring of subsea well operations across the Yokogawa world. We netted a reduction in cost and engineering effort, since the toolkit will contain templates for programming, and a reduction in time spent during the design, implementation and testing phases. At the same time, we made troubleshooting easier, maintenance simpler and instituted a better MoC process. We can build, validate and test one well, and once it is proven right, we can efficiently replicate other wells, even multiple wells, maintaining quality of engineering," Karkan said.

"Since the original idea came from Yokogawa," she concluded, "we're going to use it everywhere we use a Yokogawa control system. If we use a different control system vendor, we are expecting them to follow this same template."