Recent regulatory and voluntary initiatives to address methane emissions from oil and gas operations will expand multi-scale methane measurements across the supply chain. Interpreting, aggregating, and reconciling these measurements can provide an up-to-date estimate of US methane emissions across multiple scales – site, region, basin, and national. The annual methane census tools project will develop frameworks to generate periodic measurement-based methane emission data and supply chain-specific emissions estimates. The work plan for 2023 will focus on creating the underlying software and data management infrastructure to be able to acquire, assess, integrate, anonymize, and publish up-to-date datasets on US methane emissions across different regions and supply chains. The following tasks will be completed by Q4 2023.

A unified framework for creating a US methane census using top-down estimates (satellites, aerial systems) will be developed. This framework will describe site- and basin-specific activity data structures, quality controls and completeness checks for emissions data, and methods to extrapolate emissions across a basin from representative facilities. In addition, data acquisition and integration methods will be developed to combine data across operators and technologies. Initial work will focus on oil and gas infrastructure in the Marcellus basin (includes both upstream and midstream infrastructure).

To illustrate the functionality and use of measurement-based US methane census, detailed emissions estimates using the methods developed in Task 1 for the Marcellus basin will be developed, subject to satisfying anonymization requirements.

Accurate and high-resolution gridded inventories of methane emissions are critical for a variety of applications. Existing public gridded inventories are not updated regularly, provide coarse spatial resolution (~0.1° x 0.1°), and are primarily driven by public activity data sets and emission factors. The aim of this task is to develop a framework to provide regularly updated, high spatial resolution, gridded methane emissions inventories that blend recent activity data with measurement-based emission estimates (see Projects 3-4). Initial work will focus on developing this framework using a small-scale case study in the Marcellus or Permian basin with expansions planned in Year-2 and beyond.

Reconciling inventory estimates with measurement-based estimates is key to bridge the gap between top-down and bottom-up emissions estimates. The long-term goal of the methane census tool is to reconcile measurements with US GHG emissions inventory. As more data are collected, the gap between top-down, measurement-based estimates and inventory is expected to reduce, due to improvements in the GHGRP and GHGI and more flexible reporting method currently being proposed. This task will establish initial standards for reporting and combining activity, measurement, and top-down estimate data. Using these standards, it is possible to generate GHGRP (or other) inventory estimates using data reported in a standardized format. In Year-1, a site-level inventory development tool will be prototyped that will digest reported data, develop GHGRP-compliant inventory estimates, and compare with measurement-based estimates at the equipment- and site-level. In combination with the methane census tool, this tool can provide effective comparisons at the site, operator, and basin scales for company reporting. Initial tool development will focus on upstream production facilities, demonstrated in one shale basin, with future years expanding scope and coverage. This GHGRP-based inventory generation tool will be integrated with the data interchange standards described in Project 4(c).