A53M-3391:
Measurements of Point Source Methane Emissions in the Barnett Shale and Eagle Ford Basins
Friday, 19 December 2014
Tegan Noel Lavoie1, Paul B Shepson1, Maria Obiminda L Cambaliza1, Anna Karion2,3, Colm Sweeney2,3, Eric A Kort4, Bill Hirst5, Sonja Wolter2,3, Stephen A Conley6, Ian C Faloona7, David Lyon8 and Ramon Alvarez8, (1)Purdue University, West Lafayette, IN, United States, (2)University of Colorado at Boulder, CIRES, Boulder, CO, United States, (3)NOAA/Earth System Research Lab, Boulder, CO, United States, (4)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (5)Shell Global Solutions International B.V., The Hague, Netherlands, (6)University of California Davis, Davis, CA, United States, (7)Univ California, Davis, Davis, CA, United States, (8)Environmental Defense Fund, Austin, TX, United States
Abstract:
The global average temperature is rising as a result of anthropogenic emissions of greenhouse gases. The two organic carbon gases that contribute most to this warming are carbon dioxide (CO2) and methane (CH4). CH4, however, is 34 times more potent as a greenhouse gas than CO2 on a 100-year timescale, and 86 times more potent on a 20-year timescale. The ~12 year lifetime of CH4 means that measures to control methane emissions on the near-term time scale may have a relatively large climate benefit. The past decade has witnessed a dramatic increase in the reliance on natural gas (NG) to meet the energy needs of the U.S. To enable informed greenhouse gas policy and mitigation efforts, a comprehensive understanding of the nature and magnitude of CH4 emissions for various related NG technologies and engineering practices is required. Here we report results of our recent studies of the CH4 emission rate observed at eight different biogenic and NG point sources in the Barnett shale basin and a dozen well pads in the Eagle Ford shale region of Texas. We compare our field measurements to reported inventory estimates from the Greenhouse Gas Reporting Program (GHGRP). Using an aircraft-based mass balance approach, we found that the summed observed CH4 emission rates for our study sites were a factor of 2.5 to 4.5 greater than the GHGRP-based estimates, for the 8 sources we investigated in the Barnett shale region. The sum of the 5 Barnett NG sources we quantified had on average CH4 emissions 17.5X higher than the GHGRP inventory indicates. The sum of the 3 landfill emission rates were on average 1.5X greater than the inventory values. In the Eagle Ford shale region, high variability was observed in repeated measurements at the same well pads, highlighting the difficulty of assessing the character and statistics of the distribution of emissions from individual pads. These results indicate a need for better methods of emissions monitoring and reporting and highlight the continuing importance of effectively connecting bottom up and top down methods.
