Challenges with Developing a Measurement-Based Basin Methane Intensity Estimate

Methane intensity, the emissions relative to production, has been a focus in recent regulations on fossil fuel imports and domestic production globally, given the climate benefits of methane emission reductions. Methodological frameworks to create annual measurement-based emissions inventory estimates and calculate methane intensity using snapshot measurements have been developed. However, there are still multiple decision points within these frameworks, including several affecting methane intensity calculations, whose impact may be underappreciated. These include uncertainty in the underlying facility population and associated production in purview.

In this work, we discuss the development of a comprehensive measurement-based inventory for the dry gas Haynesville Shale Basin, located in northwest Louisiana and northeast Texas in the United States. The inventory was developed using Bridger Photonics LiDAR data. From a measurement dataset covering 7% of all facilities, we estimate annual basin total emissions of 1,030 [710, 1,530] Gg/year and a methane intensity of 1.13% [0.78%, 1.68%] (95% confidence intervals), in agreement with previous studies in the region. We then show that using different facility population data and applying different basin definitions result in a ~15% and ~75% change in the methane intensity, respectively. As such, this work demonstrates the importance of considering all aspects of the methodology to generate comparable methane intensity estimates.