During a risk assessment of Chevron’s oil fields in Bakersfield, Calif., the company learned that several key facility control systems were obsolete and had a high risk of unplanned shutdown. The facilities process the oil, water, and gas production for Chevron’s field sites in that area. To remedy its obsolete PLC problem, Chevron decided to update its PLC hardware and programming.
Because any project to upgrade the at-risk systems would involve around 10 sites, there was a great deal of concern that a shutdown of any operation could result in millions of dollars of lost revenue for each facility. Since this level of loss was not an option for Chevron, the upgrade project parameters required zero programming errors and no lost production. Additional metrics for the project included project schedule management, cost considerations, safety and environmental metrics (emissions), and commissioning time.
To ensure program parameters were met in this multi-year upgrade project, Chevron decided to incorporate dynamic simulation into the project to verify programming code integrity and test functionality during Factory Acceptance Testing (FAT) before deployment of the new control systems to ensure a seamless switchover. This use of dynamic simulation was particularly important in addressing Chevron’s established practice of using checkout code during PLC commissioning in the field. The traditional checkout practice, however, provided no opportunity to test the response of critical safety systems to the new PLCs. Software-based dynamic process simulator for code checkout addressed this problem by providing a controlled test environment. It could also be used to train operators.
Using Schneider Electric’s DYNSIM simulation for the project resulted in marked improvements in safety, no lost production, and improved commissioning times for the facilities, said Trevor Ault, automation and process control engineer for Chevron’s San Joaquin Valley Business Unit.
Ault says that specific benefits of using DYNSIM software on this control system upgrade project could be measured in six areas:
- Safety. “Safety is first and most important for Chevron,” Ault said. Because PLC programming errors were caught before deployment with SimSci DYNSIM, there was no need for field programming—and the errors that often accompany it—on this project.
- Commissioning time improved. “For a roughly 300 I/0 point facility, the estimated improvement of commissioning time was 2-3 weeks,” said Ault, “which is about half of what is usually required, saving Chevron about $840,000.” The time savings were a result of catching errors in programming and loop tuning using simulation.
- Lowered training time and commissioning time. Schneider Electric was able to organize training in conjunction with acceptance testing of simulation. “Training typically takes long periods of time,” Ault said. “Operator training with simulation organized by Schneider Electric cut long, drawn out training from months to weeks, saving about four weeks of time over the course of the project.”
- Quality improvement metrics. With zero PLC programming errors ensured through the use of simulation, Ault estimates the project experienced a 20 percent reduction in field commissioning time for instrument technicians and system integrators.
- Production & Capacity. Simulation resulted in increased production by limiting any lost production during cutover, Ault said. “It also increased production capacity by testing control strategies to debottleneck the facilities. For example, one plant was in manual control but, using simulation, we tested new control strategies resulting in capacity increases of 20 percent,” he said.
- Qualitative Improvements. The DYNSIM approach was “very well received by operators in the field,” said Ault, “because it was used as a training platform to orient operators to the new controls system and graphics. Also, the operators could test out screens before startup.”
Ault added that Chevron is now using DYNSIM for all its projects, “not just the big ones. It’s now part of the lifecycle for PLC programming and system design,” he said. “We’re also using it to optimize the plant after commissioning.”
Schneider Electric has “changed the game for us,” Ault added, “DYNSIM software allows us to coordinate with operators to make sure what they wanted was put into the program and that it matches the real-world results.” Prior to using dynamic simulation, “we trusted PLC programming, but with DYNSIM we can confirm the PLC programming was done correctly.”