Automation System Case Study of Coalbed-Methane Development
- Steve K. Robertson (Halliburton Energy Services) | Mike Pool (Halliburton Energy Services) | Michael J. Farrens (River Gas Corp.) | Tammie J. Butts (River Gas Corp.)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Facilities
- Publication Date
- May 2002
- Document Type
- Journal Paper
- 91 - 101
- 2002. Society of Petroleum Engineers
- 7.2.1 Risk, Uncertainty and Risk Assessment, 4.1.5 Processing Equipment, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 3.1.1 Beam and related pumping techniques, 4.1.6 Compressors, Engines and Turbines, 4.4.2 SCADA, 7.4.5 Future of energy/oil and gas, 4.2 Pipelines, Flowlines and Risers, 4.1.2 Separation and Treating, 3.3 Well & Reservoir Surveillance and Monitoring, 4.1.9 Heavy Oil Upgrading, 5.5.2 Core Analysis, 1.6 Drilling Operations, 5.5 Reservoir Simulation, 5.8.3 Coal Seam Gas
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Can an independent producer fulfill a vision to develop and produce a coalbed methane (CBM) gas field that covers 200 square miles in a remote desert plateau in the western United States? This paper will answer that question as well as provide answers to other pertinent questions, such as:
What tools would be available to the operator to efficiently and safely produce the wells?
Will the tools allow for future expansion and/or allow new technologies to be incorporated into the system in a cost-effective manner?
This case study will show how River Gas Corp. was able to successfully meet its needs with an automation system that was jointly developed with an engineering/manufacturing company. All phases of the project, from its inception in 1991 with a 13-well pilot project to a planned 600-well development, are discussed. Innovative solutions successfully answered the previous questions and allowed the system to evolve to meet the continuing changes in expansion and production needs.
River Gas Corp., a CBM producer from west Alabama, began evaluating a new CBM project in central Utah. Empowered with the knowledge and experience gained from its 535-well Black Warrior project, it decided to invest in a 13-well CBM pilot project in 1991. It named the project Drunkard's Wash after the local landmark. Before drilling, River Gas carefully considered how it was going to operate the wells with a minimal staff while maintaining a high degree of production-measurement accuracy. Other operational areas of concern and discussion included bad weather conditions, minimal environmental impact, and an increased degree of production safety.1,2 The evaluation and justification to invest fully in the development of this new field would depend upon how much gas could be safely and economically extracted.
When the Drunkard's Wash project was in its earliest stages of evaluation, River Gas determined that an electronics-based method of flow measurement was needed. Several factors helped form River Gas' decision.
Inherent inaccuracy of a chart recorder.
Added expense of chart integration.
Cheaper cost of electronic-based systems.
After considering the options, River Gas decided to install a simple, low-cost, solar-powered, electronic gas-flow computer at each well. These units would measure the three orifice-meter process variables (static pressure, differential pressure, and flow temperature) and calculate the gas flow rate and the daily gas volume. This simple, electronic gas-measurement (EGM) device introduced River Gas to the benefits of remote, electronic-based systems for field automation.
Once the Drunkard's Wash evaluation period ended successfully, River Gas realized the enormous potential for an automated CBM field. It would be able to maintain not only a minimal operations staff but also monitor the entire operation continually from a remote station. The evolution of this system is discussed by breaking it into the following segments.
Future expansion and development.
These segments illustrate how a simple gas-measurement system has evolved into a sophisticated, remote-measurement and -control system.
The Black Warrior project (535 wells) in Alabama provided the comparative basis for most of the decisions made concerning the Utah project. The Alabama CBM wells did not produce as much gas or water and, therefore, did not require large production components. The typical Alabama CBM well had the following components: beam pump, small gas scrubber, gas orifice meter, and turbine flowmeter. In a typical day, the operator would drive to each well and drain the liquids from the gas scrubber, check the chart recorder, and write down the daily production data. One production operator would typically be responsible for operating and maintaining 20 to 30 CBM wells during a normal work day.
The experience gained from the Black Warrior project prompted River Gas to research an electronic alternative to the standard circular chart recorder for gas measurement because the accuracy of the gas-measurement and calculation methods was critical for proper lease allocation. This need encouraged investigation of a simple EGM system for each of the Utah wells. The EGM system consisted of a solar-powered gas-flow computer (GFC), a static pressure transmitter, a differential pressure transmitter, and a temperature transmitter. In 1993, however, the decision was made to increase the pilot evaluation project to 33 wells.
This simple, yet effective, EGM method provided River Gas with an important introduction into production automation. River Gas quickly realized that through an automated system, it would be able to expand the number of wells without increasing the operational staff to a level comparable to their Alabama operation. Another anticipated result was the increased operator efficiency with an automated system.3,4 This benefit was based on the belief that if operations personnel were given the ability to target specific problems when organizing their work days instead of discovering problems only when inspecting the individual wellsites, the overall operator and production efficiency would be increased. Also, a decrease in "windshield time" has a positive effect on the bottom line by reducing overtime cost, vehicle maintenance, and expense, and by enhancing employee safety (by reducing the amount of time driving). With needs acquired from previous experience and by reviewing all technological suggestions, River Gas jointly formulated a conceptual automation system with the engineering/ manufacturing company. The original concept for the automation system was based on the following requirements.
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