Natural Gas Gathering and Boosting Stations Are Ripe for Mitigation of Emissions

Abstract

As an operator of 30,000 miles of natural gas pipeline systems, including gathering and boosting (G&B) facilities, Williams is taking steps to further mitigate greenhouse gas (GHG) associated with its operations (see sidebar). The US Environmental Protection Agency (EPA) compiled data for GHG quantities as metric tons of CO2 equivalent (CO2e) based on self-reported data from the facilities as of 4 August 2019. Among the results are 13 of Williams’ onshore gathering and boosting facilities (Table 1). While this is a snapshot of one segment of a company’s operations, it illustrates the importance of mitigation throughout the natural gas value chain. Leak detection and equipment upgrades play a significant role in the mitigation of methane and carbon dioxide emissions. Various equipment components involved in G&B systems such as compressors, tanks, dehydrators, acid-gas-removal units, separators, and yard piping are recognized emitters. An EPA report issued in April, Inventory of US Greenhouse Gas Emissions and Sinks 1990-2018, (https://www. epa.gov/sites/production/files/2020-04/documents/us-ghg-inventory-2020- main-text.pdf) identified the sources of GHG emissions from G&B systems as the G&B stations and gathering pipelines. G&B stations receive natural gas from production sites and transfer it via gathering pipelines to transmission pipelines or processing facilities. Boosting processes include compression, dehydration, and transport of gas to a processing facility or pipeline. The EPA identified five major segments of the natural gas system: exploration, production (including G&B), processing, transmission and storage, and distribution. It categorized “production” as beginning at the withdrawing of raw gas at the wellsite. Emissions arise from the wells themselves and from wellsite equipment and activities such as pneumatic controllers, tanks and separators, and liquids unloading. The EPA included G&B emission sources within the production sector. In 2018, emissions from production (including G&B) accounted for 58% of methane emissions and 27% of carbon dioxide emissions from natural gas systems. Within the production data, G&B sources took the top position for the most emissions in several categories.