The Road to Updated Emission Factors to Characterize Methane Emissions for Select Emission Sources in Natural Gas Systems

摘要

Natural gas production operations are rapidly expanding globally using advanced production techniques that are opening new areas to exploration and development. New production technologies and practices, including those involving hydraulic fracturing, have spurred growth in natural gas based power generation and industrial uses and is credited with reducing greenhouse gas (GHG) emissions with the co-benefit of improved air quality. At the same time, these emerging operating practices necessitate a thorough review of existing methane quantification methods for emissions associated with venting, flaring, and equipment leaks from natural gas systems and operations. To provide robust data for characterizing methane emissions from natural gas operations, the American Petroleum Institute (API) has been engaged in efforts to gather industry data and information from U.S. natural gas production companies and analyzing the extensive database being compiled in the U.S. under the national Greenhouse Gas Reporting Program (GHGRP). This paper describes industry’s efforts to derive new emission factors to characterize key sources of natural gas production operations, including hydraulically fractured completions and workovers and gas well liquids unloading. The results of the analysis will include a comparison of new methane emission factors derived by industry to those used for the U.S. National GHG Inventory. The discussion will focus on evaluating the contribution of key sources to overall methane emissions in an effort to inform the public debate on natural gas use and its role in mitigating overall GHG emissions.