PDVSA finds PlantWeb a change for the better

Change can be both good and bad. Just ask Victor Yi Hung, instrumentation and automation advisor for the state-owned petroleum company Petroleos de Venezuela, S.A. (PDVSA). At its Jusepin complex in the 56-well Furrial oil field, PDVSA operates one of the world's largest installations to separate oil from gas.

An example of a bad change is a surge in liquid level from the wells, resulting in a gas pressure spike, which leads to the venting of gas. This has bad consequences both economically and environmentally.

An example of a good change, notes Yi, is Emerson Process Management's PlantWeb architecture with FOUNDATION fieldbus. PDVSA selected this powerful combination of new technologies to replace a traditional oil field automation system. This has lead to good consequences, something Yi appreciates.

PlantWeb is making many jobs much easier

"PlantWeb is making many jobs much easier," he says. One job that was made considerably easier and less expensive was installation. PDVSA selected the oldest of seven two-phase liquid-gas separator modules to upgrade from a supervisory control and data acquisition (SCADA) system to PlantWeb with fieldbus. Installation was done using existing wiring. Complicating matters, the upgrade involved zones where processes could not be stopped.

Based on prior experience with similar major instrument overhauls in the past that involved new technology, planners at PDVSA expected the installation to take five or six months. That, however, wasn't the case.

"Everything was installed, calibrated and commissioned completely in fifteen days," says Yi. "Total installation labor for all these tasks was reduced by a factor of at least ten."

Yi attributes these cost savings to two things. The first is that plug-and-play intelligent field instruments made installation much faster. The second is that the DeltaV system that's part of PlantWeb runs a familiar Windows-based operator interface. That reduces training and makes configuration a simple drag-and-drop operation for both the DeltaV and asset management software. Thus commissioning of the new system took place without tedious and drawn out point-to-point tests and loop-by-loop configuration and testing.

Beyond the initial savings, PDVSA also expects to reap other benefits from Latin America's first PlantWeb installation. These arise from the nature of the Furrial oil field.

Covering 22 square miles (57 square kilometers), the field produces 15 percent of Venezuela's oil. For efficiency and to minimize impact on agricultural activities, the Jusepin complex serves as a centralized processing point for the entire oil field. The daily processing capacity of the complex is 400,000 barrels of 28 API oil mixed with 95,000 barrels of water and 350 million standard cubic feet of gas.

During the separation process, sudden large slugs of liquid or gas cause surges in gas pressure. If these spikes are large enough, gas has to be vented and burned off through a flare system. That's bad enough. However, the natural variation can be made worse.

"When someone adjusts a controller incorrectly or walks away leaving it in manual operation, or if a valve became sluggish or stuck open or closed, the resulting upset can last a long time," remarks Yi. PlantWeb helps attack these problems. For example, when a valve or transmitter malfunctions, a maintenance crew can go directly to the problem source. Calibration of instruments can be done on an as needed basis, rather than according to an arbitrary schedule. These and other uses of field intelligence, says Yi, should double the effectiveness of labor and field maintenance.

Better process control also has reduced liquid level fluctuations. As a result, shutdowns of units or whole modules have decreased. There are other savings that should arise due to this improved better process control. Some of these changes may be hard to quantify, but they're still of the good variety.

Yi explains, "Less gas is flared and more liquid is recovered, with savings from an economic standpoint and in terms of environmental regulations."

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