Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Energy Sector Analysis

Background:

• Methane (CH4) is a potent greenhouse gas with significant emissions from the oil and gas (O&G) industry.
• Accurate estimation of O&G methane emissions is crucial for climate change mitigation strategies.
• Existing inventories may not fully capture the contribution of high-emission sources.

Purpose of the Study:

• To develop a spatially resolved methane emission inventory for the Barnett Shale region.
• To compare new emission estimates with existing inventories, including those from the EPA.
• To identify key O&G sources contributing to methane emissions.

Main Methods:

• Constructed a spatially resolved emission inventory for 18 source categories.
• Utilized empirical measurements from regional O&G sites and national data.
• Employed Monte Carlo simulations to calculate emission factors, accounting for fat-tail emission sites.
• Compiled spatially referenced activity data from federal and state databases.

Main Results:

• Total methane emissions in the Barnett Shale were estimated at 72,300 kg CH4 h(-1).
• Oil and gas (O&G) emissions were estimated at 46,200 kg CH4 h(-1), with 19% from fat-tail sites.
• The O&G emission estimate was 1.5 to 4.3 times higher than alternative inventories.

Conclusions:

• The developed inventory provides a more comprehensive estimate of O&G methane emissions in the Barnett Shale.
• Fat-tail sites represent a disproportionately large fraction of total O&G methane emissions.
• Gathering compressor stations were a major source of O&G emissions, with significant discrepancies compared to EPA data.