In response to continued interest about consistent greenhouse gas (GHG) emissions estimation, the American Petroleum Inst. (API) developed a Compendium of Greenhouse Gas Emissions Estimation Methodologies for the Oil and Gas Industry. To enhance the real-world application of the compendium, methodologies were examined to assess emission reductions from specific projects. This study illustrates the use of the compendium and identifies potential methodological issues. The full-length paper details technical considerations associated with estimating pre- and post-project emissions for a variety of emission reduction scenarios.