Methane Emissions from Marginal Conventional Well Sites in Colorado

Benjamin Aboagye1, Timothy Vaughn2

1Systems Engineering Department, 2CSU Energy Institute

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Background​

Marginal wells (wells that produce ≤15 barrels of oil per day or ≤90,000 cubic feet of natural gas per day) can emit disproportionately high methane levels compared to their production[1],[2].

The Colorado Methane Emissions Reduction Program (MERP) grant aims to provide federal funding to help well owners and operators detect and eliminate methane emissions from low-producing marginal wells by supporting their voluntary plugging and site reclamation.

The objectives of this study are to:

  • Select and survey a sample of marginal, conventional wells throughout the state.
  • Identify and measure methane emission sources observed on wellheads and other equipment at visited locations.
  • Understand factors that cause increased methane emissions for future prioritization efforts.

Methodology​

Reference Caption
Figure 1: Map of the 46 study sites visited, with point colors representing different operators or owners (left) and a wellhead screening with an OGI camera (right). Across all sites, 117 wellheads, 95 separators, 127 tanks, and 18 enclosed combustion devices were examined. Both the OGI camera and trace gas analyzers in a mobile lab were used together to detect and verify methane emission sources.
Reference caption

Equipment Emission Results

Equipment Emissions Count and Emission Rate with - count - wellhead, tank, separator, heater treater, ecd, pump jack engine, and compressor - Emission Rate (slpm)

Emission Correlations

Correlation Maxris with ch4_slpm, well_count, boe_perday, mcf_perday, age, eqp_count, ch4_slpm, well_count, boe_perday, mcf_perday, age, eqp_count

Comparison with Prior Study

Table 1: Bowers’ Colorado emission summary for separators, tanks, and wellheads

Equipment ScreenedEmission Source CountMeasured Source CountEmission Rate (slpm)
Separator86878294.78
Tank61131030.87
Wellhead919915.58

Table 2: This study’s Colorado emission summary for separators, tanks, and wellheads

Equipment ScreenedEmission Source CountMeasured Source CountEmission Rate (slpm)
Separator95512524.49
Tank12729423.15
Wellhead117116.97

Conclusions​

  • Separators were the most common source of emissions (51 sources out of 95 screened), while wellheads were the least common source (1 source out of 117 screened).
  • Only one emission source was identified on separators with controls, whereas 50 emission sources were observed on emissions without controls.
  • Emissions were found on 10% of controlled tanks (tanks equipped with ECDs) compared to 35% of uncontrolled tanks.
  • Regression analysis showed moderate correlations for well count and equipment count with methane emissions.
  • Weak correlations were observed between methane emissions and oil production, gas production, and well age.

Acknowledgements and Contact Information​

We gratefully acknowledge the generous support of the Colorado Energy and Carbon Management Commission for funding this project. We would also like to thank Weston Solutions for coordinating the program and engaging operators for their participation, which made this work possible.

Benjamin Aboagye
Graduate Student
Systems Engineering Department, Colorado State University
[email protected]

Timothy Vaughn, PhD
Research Scientist
CSU Energy Institute, Colorado State University
[email protected]


References​

[1] R. L. Bowers, “Quantification of Methane Emissions from Marginal (Low Production Rate) Oil and Natural Gas Wells,” GSI Environmental Inc., Austin, TX (United States), DOE-GSI-31702, Apr. 2022. doi: 10.2172/1865859.

[2] M. Omara, D. Zavala-Araiza, D. R. Lyon, B. Hmiel, K. A. Roberts, and S. P. Hamburg, “Methane emissions from US low production oil and natural gas well sites,” Nat. Commun., vol. 13, no. 1, p. 2085, Apr. 2022, doi: 10.1038/s41467-022-29709-3.

Equipment at the METEC Site