New Rules of Methane Accountability: Subpart W and OGMP 2.0 Converge

Methane management in the oil and gas sector now depends on verification rather than estimation. Regulators and global reporting initiatives increasingly expect operators to support emissions inventories with measurement-backed data that reflects real operating conditions, fundamentally changing how methane programs are designed, implemented and evaluated.

Two frameworks are driving this shift. The first is the U.S. Environmental Protection Agency’s (EPA) revised Subpart W of the Greenhouse Gas Reporting Program, which expands methane monitoring requirements and provides the data foundation for the federal Waste Emissions Charge. The second is the Oil and Gas Methane Partnership 2.0 (OGMP 2.0), a voluntary global initiative led by the United Nations Environment Programme that requires measurement-informed inventories and reconciliation between source-level and site-level emissions data.

Together, these frameworks are redefining how methane inventories are built, measured and defended.
Operators now face a practical question: How to develop one monitoring strategy that supports regulatory compliance under Subpart W and credible OGMP 2.0 Gold Standard reporting?

Congress directed EPA, through the Inflation Reduction Act, to update methane reporting and establish a charge on excess emissions from certain oil and gas facilities. Subpart W now serves two roles:

• Improve accuracy and completeness of methane reporting
• Provide emissions data that underpin the federal Waste Emissions Charge

Beginning in Reporting Year 2025, operators had to be compliant with revised monitoring requirements, inclusive of two significant structural changes:

• Inclusion of emission sources that were previously unreported or estimated differently
• Expanded use of empirical, measurement-based methods to quantify emissions

This shift mirrors the trajectory of OGMP 2.0, which centers on Level 4 quantification and at Gold Standard, reconciliation with site-level measurements. Combined, measurement has moved from a niche technical exercise to the operating system of methane compliance.

Both frameworks emphasize empirical data over generalized emission factors and recognize that site-specific conditions drive real emissions. Yet their structures differ in flexibility and scope.

Measurement philosophy

OGMP 2.0

• Requires Level 4 source-level quantification for material sources
• Allows direct measurement or engineering calculations using site-specific data
• Does not prescribe specific technologies or frequencies, provided methods are fit for purpose
• Requires both source-level and site-level measurement, plus reconciliation, for Gold Standard

Subpart W

• Allows multiple methodologies per source category, including direct measurement, engineering calculations and emission factors
• Specifies monitoring requirements for direct measurement approaches
• Requires consistent technology use across a wellsite or reporting facility in most cases
• Focuses primarily on source-level data, with limited use of site-level monitoring for “other large release events”

The practical implication is clear: Subpart W sets minimum regulatory requirements with defined technical parameters. OGMP 2.0 sets up a performance-based framework that rewards comprehensive measurement and reconciliation. For operators already investing in measurement, the overlap creates a clear strategic opportunity.

Understanding the philosophical alignment between Subpart W and OGMP 2.0 clarifies how the frameworks interact. Each OGMP 2.0 emission source category maps directly to at least one Subpart W reporting category, including: pneumatic devices, equipment leaks, reciprocating and centrifugal compressors, hydrocarbon liquid storage tanks, glycol dehydrators, flares, liquids unloading and completions and workovers.

A well-designed Subpart W monitoring program provides the technical backbone for OGMP 2.0 implementation. However, achieving alignment requires a deliberate monitoring program design and a broader shift toward measurement-informed methane management.

For operators, accurate measurement delivers value beyond regulatory reporting. It enables identification of high-emitting assets, prioritization of capital investments, reduction of product loss, and greater transparency for regulators, investors and stakeholders.

Designing methane monitoring programs with both frameworks in mind transforms inventories from compliance records into operational decision tools that strengthen emissions visibility, credibility and long-term performance.

Measurement campaigns consistently show that a small number of source categories often dominate methane inventories. Strategic decisions in these areas shape both compliance cost and credibility.

Subpart W allows three approaches:

• Component counts with default emission factors
• Leak surveys with technology-specific default “leaker” factors
• Source-level measurement using high-volume samplers or approved technologies, with the option to develop facility-specific emission factors based on 50 equivalent source types

OGMP 2.0 Level 4 allows for the development of basin-specific emission factors based on representative sampling defined by the operator. The strategic decision you must answer is whether to remain factor-based or transition to measurement-derived factors. Measurement requires greater upfront effort but significantly reduces uncertainty, particularly in basins with high variability.

Subpart W offers default factors based on equipment counts, measurement during normal actuation over a 15-minute period, and annual two-minute monitoring per device to determine malfunction rates.

OGMP 2.0 accepts malfunction-based and direct measurement approaches but favors combined methods that quantify both malfunction frequency and emissions during normal operation.

Integrating malfunction detection with direct emission quantification will improve inventory accuracy and inform maintenance priorities.

Subpart W permits a default of 92% destruction and removal efficiency (DRE). Higher DRE claims of 95% or 98% require compliance-grade monitoring under other rules. Direct measurement technologies may justify efficiencies above 98% with approval.

OGMP 2.0 traditionally treats direct DRE measurements, such as Video Imaging Spectro-Radiometry (VISR), as meeting Level 4 requirements.

For operators with variable flare performance, direct measurement provides operational insight, not just reporting compliance. This approach reveals combustion efficiency under real wind, flow and composition conditions.

Subpart W requires use of site-specific stack testing data if available. If not, operators may rely on default factors or manufacturer data.

OGMP 2.0 considers only direct measurement, through continuous monitoring systems or stack testing, as Level 4-compliant.

Where methane slip represents a material portion of emissions, relying solely on default factors may understate variability. Continuous monitoring exposes operational inefficiencies that would otherwise remain hidden.

Subpart W defines “other large releases” narrowly, focusing on confirmed super-emitter events under New Source Performance Standards Subpart OOOOb. Engineering calculations or site-level monitoring may be used.

OGMP 2.0 defines this category more broadly, covering all unintended releases. It also requires separation between technologies used for source-level and site-level reconciliation under Gold Standard.

Operators pursuing Gold Standard must design monitoring architectures that avoid technological overlap and maintain data integrity.

Organizations that treat Subpart W as a narrow compliance obligation meet regulatory requirements, but they risk building monitoring programs that must be redesigned as expectations evolve. Companies that invest in robust, measurement-informed inventories today position themselves to navigate regulatory change, reduce emissions and demonstrate true leadership in methane transparency.