Venezuela is home to the Western Hemisphere’s largest oil reserves. Its economy is extremely oil-dependent, accounting for roughly three-quarters of its total exports and approximately half of its government revenues. As the third largest oil exporter in the world, Petroleos de Venezuela, S.A.
(PDVSA), Venezuela’s national oil company, is constantly striving to remain competitive and profitable in the world energy scene.
In 1995, PDVSA conducted an analysis of their technology requirements for their oil production fields in Eastern Venezuela. The requirements identified included:
Because of its internationally recognized brand-name, the availability of future product support and its strong third party vendor/partners, Rockwell Automation was chosen to replace PDVSA’s legacy control
system with their 1771 PLC processors. This allowed PDVSA to incorporate technology from some of Rockwell Automation’s Encompass partners including ProSoft Technology, Inc.
In Eastern Venezuela PDVSA needed to add new tank farms, pipelines, pump and valve stations along with a SCADA system for control. Simply stated, petroleum produced at a well contains a mixture of oil, gas and water. This mixture is pumped from the pumping stations to the tank farms via a complex network of pipelines. It then undergoes field processing to separate the salable oil from the gas and water. Once the field processing is complete, 1.2 million barrels per day of crude oil are pumped through PDVSA’s 120-mile-long pipeline from the actuator network to the coast for shipment to refining facilities in the United States.
Tank Gauging, Electric Actuator and Motor Protection Relays
The SCADA system used by PDVSA communicates to many of its end devices via the Modbus protocol. The tank gauging systems monitor tank level. This data is transmitted to the A-B processor, which automatically opens and closes valves to and from the tank. The electric actuator network controls the influx of oil from the pumping stations to the main trunk line. PDVSA installed medium voltage soft starters for their control valves in order to reduce mechanical stress, starting current and hammering. ProSoft Technology’s 3100-MCM single-slot Modbus interface module was used in Allen-Bradley’s 1771 PLC processors to communicate with the tank gauging systems, the electricactuator, two-wire control systems and the motor protection relays.
Moving Heavy Crude
In 1999, PDVSA undertook a new venture in conjunction with Conoco called Petrozuata. A SCADA system was installed to control the movement of the heavy crude oil from 1500 wells in Eastern Venezuela to the coast for shipment to the U.S. for refining. Similar to the original control system PDVSA installed in 1995, this SCADA system also contained ProSoft’s 3100-MCM Modbus interface module.
HART Connectivity Needed
In March 2001, ProSoft’s sister company, ProLinx Communication Gateways, Inc. was contacted by Perez-Compac in Argentina and Rockwell Automation in Venezuela, requesting their help in communicating between Allen-Bradley’s ControlLogix using DF1 and numerous Rosemount end devices using the HART protocol. Representatives from three companies, Intelcon System, PDVSA and ProLinx Communication Gateways, worked together to test the ProLinx 4127-HART-DFCMgateway. Approximately 15 HART Multidrop modules uderwent extensive factory acceptance testing for control of PDVSA’s crude oil production units in eastern Venezuela.
“The ProLinx 4127 HART Multidrop module allows one DF1 port to connect to eight HART channels. It provides maximum efficiency for HART networks,” said Franco Melchiorre, Latin American Regional Sales Manager for ProLinx Communication Gateways, Inc. “This gateway allows full access to the digital configuration, diagnostics and maintenance information for up to 120 instruments. Since they are stand-alone, DIN-rail mounted modules, front access to all ports is quick and easy.”
The addition of the eight channel HART modules is part of a secondary recovery project for PDVSA in the largest oilfield in eastern Venezuela, Furrial Field, which produces approximately 450,000 barrels per day.
PDVSA was introduced to the ProLinx HART modules earlier this year, when they installed a four-channel version or the ProLinx module (4107-HART-DFCM) in the oil and gas production division in western Venezuela at Lake Maracaibo. In that instance, the ProLinx HART Multidrop module was connected to an Allen-Bradley Micrologix 1500, allowing HART devices such as Fisher-Rosemount Mass Flow Meters to communicate on channel one and intelligent transmitters on channel 2.
According to ProLinx Communication Gateways’ CEO, Doug Sharratt, the demand for a HART interface has been growing for a number of years. “HART is extremely popular in the process control industry,” said Sharratt. “Many businesses are seeing significant improvement in their information management systems, at a substantial cost savings by using the HART protocol. HART users needed an easily installed, fast and inexpensive interface to connect them to a variety of processors. The ProLinx modules provide that connectivity.”