ANALYSIS INDICATES BENEFITS OF SUPERVISORY PUMP-OFF CONTROL

Todd A. Blackford, John R. Dunn, Randy R.Joseck
Amoco Production Co.
Houston

A pilot testing program of supervisory pump-off control (SPOC) systems on a commercial scale determined that this advanced technology could provide sufficient benefits to justify retrofit of analog pump-off controllers.

In addition, experiences of other operators were reviewed to augment the favorable pilot-test results.

The SPOC systems can provide engineering and operations personnel with a more complete well-surveillance package that includes diagnostic capabilities. When a lift-equipment failure or anomalous operating condition occurs, SPOC hardware can allow individual well site controllers to send alarm signals, digitized dynamometer cards, and other pertinent operating data to a host computer.

Besides providing for an immediate response to an upset well condition, the stored data allow for more accurate determination of the problem source. Effective lift design modifications can then be accurately developed.

PUMP-OFF CONTROL

For West Texas and eastern New Mexico producing areas, analog pump-off controllers are widely employed by numerous operators to optimize fluid recovery and reduce equipment failures for beam-pumped wells.

Beginning in the early 1970s, Amoco began experimenting with automation of oil field production operations. Due to significant reserve holdings and the desire to maximize recoveries by minimizing producing fluid levels and equipment downtime, the West Texas and eastern New Mexico producing areas were designated as priority areas for automation implementations.

By the early 1980s, the vast majority of production operations in these areas were automated. Pump-off controller installations were a portion of an overall lease automation strategy that included:

Automatic well testing
Injection well monitoring and control
Producing well monitoring
Production and injection facility surveillance
Operator alarm notifications.

With this experience, coupled with the desire to evaluate the profitability of the latest automation technologies, Amoco began exploring the benefits of SPOC system technology as a potential upgrade of existing analog pump-off controllers.

By using a portable analyzer, the analog pump-off controllers could provide a "live action pumping card" that allowed operations personnel to witness the well conditions and adjust set points for shutting down the beam pumps as well as determining if well bore fluids were pumped off.

But pumping cards, recorded during equipment failures, were not saved for future analysis. Also, pumping conditions were not transmitted to a central terminal.

With SPOC systems as shown in Fig. 1:

Live pumping conditions could be viewed at a centrally located terminal.
Dynamometer cards were saved for viewing following an equipment failure.
Diagnostic programs could be run to aid problem identification.
Trending packages could be used to monitor producing conditions and predict problems before they occurred.

SPOC ANALYSIS

It became evident that SPOC systems provide superior capabilities as compared to the analog controllers in use.

The problem became one of defining what benefits could be derived from the improved capabilities provided by the SPOC systems.

To begin addressing this problem, pilot testing was initiated for locations ranging in size from 1 to 10 wells.

The initial desire was to gain familiarity with the various systems commercially available.

Advantages and disadvantages of each system were documented as well as actual benefits perceived. In addition, tours of outside operated installations and vendor demonstrations/seminars were held to gain further knowledge on systems and operations.

At the conclusion of this data-gathering phase, the decision was made to proceed cautiously with SPOC system deployment.

Initial justification for these installations included:

Production increase of 1%
Lift-equipment failure frequency reduction of 10%
Power consumption savings of 2%.

These benefits were based upon documented results in the Permian basin area of West Texas by Shell Western E & P,l-4 and verified by pilot testing.

Following approximately 1 year of experience with SPOC systems for beam-pumped producers that were previously equipped with analog pump-off controllers, an appraisal was performed to identify average realized benefits. A total of 671 wells were involved in the post installation analysis.

These wells were distributed across eight distinct operating areas, and the appraisal was divided into two primary components. The first represented a statistical review of benefits obtained due to fluid production increases, energy consumption reductions, and equipment failure decreases.

To accomplish the statistical evaluation, data were compiled for previous operations using analog pump-off controllers and compared to similar data following SPOC system deployments.

The second component represented an operational review in which meetings were held with automation, operation, and supervisory personnel responsible for actual system use. These operational meetings were valuable in identifying other variables that may have impacted the statistical evaluation.

In addition, the operational appraisal fostered employee input that will be used to optimize future system designs.

STATISTICAL APPRAISAL

Table 1 summarizes the producing depths and type of recovery mechanisms (primary or waterflood) employed in each of the eight operating areas. Of the 671 available, 546 were included (Table 1) in the detailed statistical review.

A total of 125 beam-pumped producers were removed from the study because there was either a change in their producing well depth, there was a revision in lift equipment, they were shut in, or the wells were abandoned.

Removal of these wells assured comparison of like operating conditions before and after SPOC installation. Overall, 81% of the available wells were in the analyzed statistical population.

Table 2 compiles the failure data. Downhole pumprelated failures declined by 20%. Before SPOC the annual failures averaged 495; afterwards the average was 396.

Likewise, sucker rod-related failures declined by 5% overall, from 350 before to 332 after installation of spookiest.

Surprisingly, overall spokes frequency increased, on average, by 31% despite the fact that spokes frequencies for leases in the West Texas and eastern New Mexico producing areas had declined both in 1988 and 1989. Personnel in several locations credited the increase in workovers to improved data availability with the SPOC systems. Wells needing stimulation or repair could more readily be identified.

Increased failure frequencies for Areas B, E, and F were attributed primarily to lift-equipment fatigue. Recent budget restraints, due primarily to lower oil prices over the past few years, have led to more careful scrutinizing of the replacement of lift equipment.

Replacing lift equipment has become more difficult to justify economically. This has resulted in higher average equipment service life in some areas during the past few years, and has led to increased failure frequencies.

No attempt was made to adjust the failure data base to account for increased equipment service life.

Table 3 compares fluid production and run-time data for the eight areas studied. For analyzing SPOC benefits, these data were considered to be the most reliable data readily available from Amoco's central computing system.

In addition to before and after comparisons of these data, an artificial parameter of barrels of fluid produced per hour of unit run time was developed to measure electrical power consumption.

The effort required to rigorously record or define actual power consumption on a well-by-well basis for a survey of this size was cohsidered to be too extensive a task.

This artificial parameter provided an acceptable indication of actual improvements in efficiency obtained.

From the data contained in Table 3, an average fluid production increase of approximately 10% was identified with an overall increase in average run time of 2%.

Although these benefits are much greater than originally anticipated, the recommendation was made to justify further installations using a 3% production increase combined with previously detailed 14% decrease in equipment failure frequency.

Electrical power consumption reductions are not recommended for inclusion in future justifications because power use actually increased. This increase was due to increased fluid production, despite improvements in overall lifting efficiency.

As shown in Table 4, all of the eight areas surveyed experienced benefits of a magnitude sufficient to economically justify SPOC system deployment. On average, the benefits pay out the installation cost in less than 1 year.

Following SPOC system deployment, the capability to monitor, control, and optimize beam pumping continuously provided the primary operational changes that led to the cost saving. However, these systems increase the awareness and knowledge of the operations personnel as to lifting parameters. This also contributed to the level of benefits obtained.

OPERATIONAL APPRAISAL

To obtain comments on actual performance, eleven separate meetings were held at field operations offices. These meetings were attended by operations, engineering, automation, and supervisory personnel with responsibility for SPOC system operation.

At the time of these meetings, the systems in service were manufactured by Automated Controls Inc., Baker Lift Systems, and Delta X Corp.

Preliminary discussions on statistical appraisals were completed to assure sufficient understanding of tabulated results. Comments generated during these discussions resulted in the following items being prioritized as principal operational concerns:

Communications interface-Because the SPOC central host computing systems were purchased in conjunction with individual well site controllers, difficulty was encountered in linking host computer data to a separate Amoco automation computing system.
Although the decision was made to deploy SPOC systems prior to completely resolving the linking issue, operations personnel were sometimes found to be searching for desired data contained within one of the two systems.
Organizational impact - With enhanced troubleshooting and diagnostic capabilities, traditional roles of operations personnel shifted away from "checker" and more towards "well analyst" functions.
While this creates a more desirable and challenging position, some difficulty was encountered adjusting to the changed operational mode.
Maintenance concerns-The need for spare parts inventories was identified to assure minimal well downtime during controller or system repair.
In addition, assignment of the maintenance function to appropriate personnel became a concern, as with most automation systems, to assure optimum system performance.
Finally, a cost-monitoring system was requested to document maintenance costs for inclusion in future economic and purchase analyses.
Vendor service-Vendor support of the commercially available systems appeared to impact the speed upon which operational personnel began obtaining projected benefits.
Further training-Although initial training was provided, follow-up training at 3-6 month intervals was deemed necessary to assure maximum use of troubleshooting and diagnostic capabilities.
Equipment performance monitoring-Documentation of component failures was considered a necessity to assure that performance problems were corrected prior to incurring significant repair costs. In addition, adequate documentation assured that concerns about appropriate system design could be addressed for future applications.

As with other automation tools, the operational appraisal demonstrated that sufficient training, experience, and support are required to assure maximum benefits from deploying SPOC systems.

ANALYSIS RESULTS

The preceding analysis for future pump-off control system upgrades with SPOC system technology indicate that:

Production rates can be expected to increase by 3%, on average.
Lift-equipment failure frequencies can be expected to decrease by an average 14%.
Although energy consumption efficiencies can be expected to improve, overall reduction cannot be anticipated because of the increase, on average, of fluid production.
The impact of SPOC systems on operations should be evaluated to ensure that the full benefits are obtained. The technology is of maximum value when fully and efficiently utilized.
Based upon these results, Amoco will pursue future installation of SPOC systems wherever these benefits provide sufficient economic incentive.

ACKNOWLEDGMENTS

The authors take this opportunity to thank Amoco Production Co. for permission to publish this article. In addition, the efforts of all operations and engineering personnel associated with this work are also greatly appreciated.

REFERENCES

Dunham, C.L., "Supervisory Control of Beam Pumping Wells," SPE Paper No. 16216, SPE Production Operations Symposium, Oklahoma City, Mar. 8-10, 1987.
Jentsch, W.A. Jr., and Marrs, R.D.,"Computerized Automation of Oilfield Production Operations: An Extensive Five-Year Study Into the Costs and Benefits," SPE Paper No. 15392, SPE Technical Conference and Exhibition, New Orleans, Oct. 5-8, 1986.
Lindley, T.M., "Pumpoff Controller Qualifying Project: A Discussion of the Process and Results," Part VI of SPE Paper No. 19721, SPE Technical Conference and Exhibition, San Antonio, Oct. 8-11, 1989.
Neely, A.B., and Tolbert, H.E., "Experience with Pump-Off Control in the Permian Basin," SPE Paper No. 14345, SPE Technical Conference and Exhibition, Las Vegas, Sept. 22-25, 1985.