AUSTIN, TEXAS (April 19, 2004) — At the Loma la Lata gas field in Neuquen Province of western Argentina, Repsol YPF has retrofitted its main low-temperature separation (LTS) complex and much of the associated gathering system with PlantWeb® digital plant architecture from Emerson Process Management. PlantWeb is implemented using the DeltaV™ digital automation system with advanced control software, AMS™ Suite predictive maintenance software, and an Ethernet LAN that includes both fiber optic and wireless segments.
 PlantWeb automation architecture helps Repsol YPF minimize environmental impact on the sensitive Patagonian desert, where the LTS complex forms a landscaped oasis.  Digital valve controllers form the base of PlantWeb architecture. Fisher® FIELDVUE® Digital Valve Controllers, shown here on Fisher easy-e® control valves, communicate using FOUNDATION fieldbus. Editors: For high-resolution images, click here. |
The result is state-of-the-art integration of process controls in the separation complex with those of associated wells, field separators, and compressors as far away as 10 kilometers. The automation system embraces more than 4,000 field inputs and outputs—both continuous (analog) and discrete (switched)—and three control rooms.
More particularly, the DeltaV system replaced a 20-year-old distributed control system in one LTS plant of the separation complex and a PLC network in another, then was extended to a new amine sweetening plant. Constantly expanded, the system now includes DeltaV controllers and workstations at 14 distant compressor stations linked by wireless Ethernet. Remote terminal units at 60 wells and several primary separator units have been incorporated by conventional SCADA radio. Repsol YPF has also implemented separate DeltaV systems in two smaller gas plants in the field.
"One major benefit is better stewardship of the natural environment of the Patagonian desert," said Repsol YPF's Production Manager Miguel Sánchez. "That's especially important to the indigenous Mapuche communities who occupy big areas of the field. The DeltaV system and PlantWeb architecture are indispensable aids for managing emissions, preventing spills, improving safety, maintaining our ISO 14000 certification, and reducing worker presence in the field."
Considering the size of the field, that is a tall order. With 196 major wells and average daily production of 40 million standard cubic meters (1.41 billion standard cubic feet), Loma la Lata is the largest producing gas field in South America. The main separation complex, in turn, is the biggest in Argentina, having a capacity of 30 million standard cubic meters per day. This may be the world's most widely extended application of PlantWeb architecture.
The architecture of an automation system is the concept that governs apportionment of tasks among the elements of the system (operator stations, controllers, and field instruments) and interconnections among those elements. PlantWeb is Emerson's version of the latest generation of automation architecture, generally known as field-based or digital.
The preceding generation, that of conventional distributed control systems and PLC networks, was based on field instruments (transmitters and control valves) that used analog electronics and analog signals-typically 4-20 milliamps. PlantWeb architecture, by contrast, is based chiefly on "smart" or "intelligent" field instruments, which have become commonplace in the last five years. Smart instruments are those that employ computer circuitry and communicate by high-speed digital means such as FOUNDATION fieldbus or HART protocol.
A FOUNDATION fieldbus "H1" segment handles power and digital communication for as many as 16 instruments with one multidrop twisted-pair cable. HART protocol superimposes bi-directional digital pulses on a conventional 4-20 milliamp signal from a transmitter or to a control valve.
The DeltaV automation system, in turn, was designed primarily to implement PlantWeb architecture. It is characterized by modularity in the controllers through which field instruments communicate; open, interoperable standards such as Microsoft Windows and Ethernet; scalability from the smallest plants to the largest; and advanced modular software.
For instance, Emerson's AMS Suite: Intelligent Device Manager software works with intelligent field instruments to provide remote instrument configuration, calibration, diagnostics, and preventive maintenance. Acting through FOUNDATION fieldbus, AMS Device Manager enables Repsol technicians to resolve problems in smart transmitters and control valves at distant locations. Results include manpower savings, higher accuracy and reliability, tighter control, and greatly reduced intrusion into environmentally and culturally sensitive zones.
"One of the best things about the DeltaV system with PlantWeb architecture," said Instrumentation Project Engineer Luis Troncoso, "is that its flexibility and modularity accommodate growth of the plant complex and gathering system very efficiently. We can easily connect instruments that are 10 meters or 10 kilometers away, whether they communicate by FOUNDATION fieldbus, 4-20 milliamps, Modbus, or anything else."
"It's just a matter of providing the appropriate input-output modules for DeltaV controllers that can reach across great distances with wireless Ethernet," explained Troncoso. "We can configure every one of those field instruments with the same simple drag-and-drop tools. They form one seamless automation system, without having to use gateways or other clumsy things like that."
An important aspect of PlantWeb architecture is trouble-free compatibility with other automation systems, enterprise resource planning systems, and so forth. At Loma la Lata, for instance, Repsol YPF's DeltaV system is integrated with Halliburton Landmark's TOW/cs management solution for oil and gas production data.
"What PlantWeb has done for Repsol YPF," concluded Production Manager Sánchez, "is give us an automation system we can be confident in—one that can follow the growth of our complex without problems, and without increasing our payroll. I don't know of any other way to do that so well."
Emerson Process Management (www.emersonprocess.com), an Emerson business, is a leader in helping businesses automate their production, processing, and distribution in the chemical, oil and gas, refining, pulp and paper, power, food and beverage, pharmaceutical, and other industries. The company combines superior products and technology with industry-specific engineering, consulting, project management, and maintenance services. Emerson brands include PlantWeb®; Fisher®; Micro Motion®; Rosemount®; DeltaV™; Ovation®; and AMS™ Suite.
St. Louis-based Emerson (www.gotoemerson.com) is a global leader in bringing technology and engineering together to provide innovative solutions to customers in process control; electronics and telecommunications; industrial automation; heating, ventilating, and air conditioning; and appliance and tools. Sales in fiscal 2003 were $14 billion.
PlantWeb, DeltaV, FIELDVUE,
easy-e, Fisher, Micro Motion, Rosemount, Ovation and AMS Suite are marks of
Emerson Process Management. FOUNDATION is a mark of the Fieldbus Foundation.
HART is a mark of the HART Communications Foundation. Other marks are the
property of their respective owners.