Summary
Clean, inexpensive, and reliable on-site electric power generation for
remote wellsites is an emerging need. There is a growing demand for electric
power sources in the range of ½ to 1.5 kW to run pumping units and pumps on
liquid loaded gas wells. To understand one possible option, a pilot project
consisting of three 0.8-kW Stirling cycle electric generators was conducted in
Wyoming.
One generator was installed driving a conventional beam pump at the US
Department of Energy’s (DOE) Rocky Mountain Oilfield Testing Center (RMOTC).
Two generators were installed for telemetry power service on well pads in the
Wamsutter gas field. In addition to these two applications, small gas-fired
generators could provide power for cathodic protection, chemical dosing
systems, and other low-rate pumping requirements.
The pilot demonstrated that a Stirling cycle generator can pump a small well
and provide supervisory control and data acquisition (SCADA) power even in cold
weather conditions. A simple fuel-control and conditioning system provided
reliable operation when properly installed. Operations and maintenance
observations from the 1-year pilot are presented.
Stirling cycle engines are external combustion engines which offer some
advantages over traditional internal combustion engines: lower maintenance
cost, low NOx emissions, and the recovery of heat for process uses. In fact,
the current commercial equipment is best thought of as a ¾-kW cogeneration
unit.
Introduction
The combination of higher oil and gas prices over the past decade coupled
with increasing concern over greenhouse gas emissions has increased the
incentive for well operators to use electric-driven production equipment
located at the wellsite. In many cases, wells are located far from the
traditional electric utility and a remote power source is required. At this
time, there are few options to provide the electric power in the ½- to 1.5-kW
range at remote wellsites.
Services that can be improved using electric power at wellsites include beam
pumping, chemical injection, cathodic protection, and SCADA. In addition, there
are potential future services such as gas well deliquification (Dotson et al.
2006) or tank vapor recovery which could be enabled by electric power.
To investigate the potential of a small, low maintenance gas-fired electric
generator, three Stirling cycle electric generators were installed in
Wyoming.
This paper will outline the alternatives available for low power generation
at wellsites. This paper will also show how a gas-fired generator fits into the
mix, and why a Stirling cycle generator was selected for testing. The Stirling
cycle will be briefly described, followed by the design for power storage and
fuel gas supply for the Wyoming installations. The results from both SCADA and
well-pumping applications will be provided, along with the overall conclusions
from the test.
© 2008. Society of Petroleum Engineers
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History
- Original manuscript received:
7 April 2008
- Meeting paper published:
16 June 2008
- Revised manuscript received:
19 August 2008
- Manuscript approved:
20 August 2008
- Version of record:
15 December 2008
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