With the beginning of the reporting year 2025 approaching, don’t get caught off guard by the future inventory emissions from the recent Subpart W revisions. Insightful planning today is crucial to effectively reducing future emissions in ways that fit within your operational objectives.
Subpart W revisions were enacted to address potential data gaps and suspected underreporting of emissions calculated using the originally published methodologies and emission factors. The update included adding previously overlooked emissions categories, applying stricter emissions factors, and implementing methodologies that rely on continuous real time data already being collected at many oil and gas facilities.
Here are some important summaries for our clients to consider:
New emission sources operators need to account for:
- Any Large Release Event captured and reported to the EPA (Super Emitter Program from OOOOb)
- Engine crankcase venting
- Produced water tanks
- Nitrogen Removal Units
- Mud degassing from drilling in oil producing zones
- Methane slip from combustion units
- Blowdown venting
Broader calculation methodologies to incorporate:
Equipment Type | New Methodology |
Pneumatic Devices | Direct emission measurement, Emission factors changed |
Pneumatic Pumps | Direct emission measurement |
Dehydrators | Measurement + engineering calculations |
Completions & Workover with hydraulic fracturing | Direct emission measurement |
Hydrocarbon liquids storage tanks | Measurement + engineering calculations |
Associated natural gas | Direct emission measurement |
Centrifugal compressors | Direct emission measurement |
Reciprocating compressors | Direct emission measurement |
Equipment leaks | Direct emission measurement, Measurement + engineering calculations Emission factors changed |
New uses of existing inspection data, particularly at oil and produced water tanks include:
- Refining open thief hatch data by using OGI inspection data to supplement AVO inspection observations and reduce the total estimated time open to atmosphere.
