UNION PACIFIC INSTALLS AUTOMATED WELLHEAD SYSTEMS

Union Pacific Resources Co. (UPRC), Fort Worth, is installing automated wellhead systems on company operated wells, mostly in Texas and Wyoming. At yearend 1992, UPRC had installed remote terminal units (RTUs) on about 320 wells to monitor operating parameters, measure gas production, and control wellhead chokes. The total includes 44 wells in a successful $1 million pilot project completed last year in Stratton field of South Texas, about 40 miles southwest of Corpus Christi.

Jan. 26, 1993

5 min read

Union Pacific Resources Co. (UPRC), Fort Worth, is installing automated wellhead systems on company operated wells, mostly in Texas and Wyoming.

At yearend 1992, UPRC had installed remote terminal units (RTUs) on about 320 wells to monitor operating parameters, measure gas production, and control wellhead chokes. The total includes 44 wells in a successful $1 million pilot project completed last year in Stratton field of South Texas, about 40 miles southwest of Corpus Christi.

If installations proceed as expected, UPRC by yearend 1994 will be operating about 1,290 of 2,200 oil and gas wells by way of RTU based automated wellhead equipment. Cost of the program is estimated at $16 million, but UPRC could extend it to more wellsites.

UPRC expects savings from more efficient automated operations to more than offset installation expense. The automation program is not affecting company reserves but is improving operating efficiency and speeding the rate at which UPRC expects to produce the reserves.

Preliminary calculations show automating wellhead functions company wide could increase gas production by 5%, reduce well downtime 5-10%, and cut contract labor costs by 10%.

Results of the 44 well Phase I pilot show UPRC could recover the cost of installing Stratton field systems in as little as 2 1/2 years. Stratton Phase II automation is to include RTU installations by yearend 1994 on 397 wells at 272 locations.

POINTS OF SAVINGS

Jack L. Messman, UPRC president and chief executive officer, said declining personal computer costs allow oil and gas producers to tap additional reserves in old fields by applying new technology.

Messman estimates computing costs have dropped to as little as $400-500/million instructions/sec (MIS) from about $57,000/MIS.

UPRC said Stratton field, with cumulative production of 2.5 tcf of gas at yearend 1992, was the best place to begin its field automation program. With individual wellhead flows ranging from 50 Mcfd to 2 MMcfd, the field's combined production accounts for about 14% of UPRC's 608 MMcfd of gas production. About 80% of UPRC reserves is made up of gas.

UPRC figures it spent about $24,000/well in the Stratton pilot to buy and install system components. The company expects Phase II spending to average about $15,000/well. In some cases, one RTU will be able to control as many as four wells.

Of the 1,290 wells it expects to automate by yearend 1994, UPRC has completed installations at about 100 wells in the Carthage area of East Texas, 120 Austin chalk wells in South Texas, 40 wells in Bruff and Wamsutter fields near Rock Springs, Wyo., and 10 in the Denver area. UPRC also has automated wells on seven platforms in the Gulf of Mexico.

In addition to the 397 Stratton wells to be automated during the next 2 years, UPRC has approved installations on 400 wells in the Carthage area, 80 in the Austin chalk, 50 Wamsutter wells, and 44 Bruff wells.

SYSTEMS DESCRIPTIONS

UPRC is installing automated wellhead systems provided by different companies in different fields.

Systems on Stratton wells are based on Siemens hardware provided by Praxis Instruments Inc., Houston. Austin chalk wells use equipment provided by Remote Operating Systems, San Antonio, and Carthage area wells use electronic flow computers provided by Applied Automation, Bartlesville, Okla.

For wells in Stratton field and around Rock Springs, Praxis created the software needed to control system hardware within specifications developed by UPRC. The software allows UPRC to monitor each well's intermitter, plunger lift, safety valves, gas lift, choke, or flow control to determine production rates accurately and instantly. Praxis also configured UPRC's host software and installed all hardware in Stratton field.

Automated system components installed at the wellhead typically include the RTU, an adjustable choke with electric actuator, and four 90 amp batteries and a solar panel for recharging. RTUs are housed in protective enclosures and batteries in separate steel, weatherproof boxes. A 20 ft antenna relays wellhead pressure, static pressure, differential pressure, and temperature to production offices.

Production office monitoring and control instrumentation includes a 486/50 megahertz host personal computer with software, a master radio, and a 50 ft antenna to allow production office workers to query RTUs within the office broadcast radius.

BENEFITS OF AUTOMATING

The automated production systems reduce the need for a pumper to visit wellsites to gather production information or change well operating parameters, UPRC said.

On wells that haven't been automated, UPRC measures gas production with familiar circular chart recorders. Pumpers collect the charts and send them to third party integrators, who then provide production numbers by modem for capture by UPRC's mainframe computer. The cost, including manpower, employee benefits, and vehicle expenses, runs about $70/chart/reading.

In addition, about 10 days typically elapse before UPRC's mainframe receives the production data, during which time the company must rely on pumpers' daily estimates of produced volumes to avoid exceeding allowables or underproducing.

By contrast, operating speeds of the RTUs selected by UPRC for the automation program are measured in milliseconds.

For control functions, each installed RTU is assigned a set point that allows UPRC pumpers with the press of a key to remotely control gas wells better and faster than is possible by daily visits to each location.

UPRC has developed optimization routines and added chokes on some wellheads to prevent problems such as overloading of produced water. When a well begins loading up with liquids, UPRC technicians immediately can begin choking the flow to capture the energy of the well to keep tubing clear.