Subpart W feeds
EPA GHGRP Subpart W is the canonical methane + CO2 inventory for petroleum and natural gas systems. Most operators have this stood up since the 2024 revisions. SB 253 Scope 1 reads directly from the same equipment-level inputs.
The August 10, 2026 deadline · for upstream operators with California revenue exposure
California SB 253 for oil & gas operators. What it requires, who it applies to, and the data infrastructure underneath it.
California SB 253 (the Climate Corporate Data Accountability Act) requires U.S. companies with $1 billion or more in revenue doing business in California to file Scope 1 and Scope 2 greenhouse-gas emissions inventories by August 10, 2026, covering fiscal year 2025. Penalties for non-compliance run up to $500,000 per entity per year. The federal methane stack softened in March 2025 (WEC dormant via Congressional Review Act) and again in April 2026 (OOOOb/c rollback). The California disclosure regime did not. For upstream operators with California revenue exposure, SB 253 is now the binding piece.
CARB enforcement discretion for first-year filings · Subpart W is the data backbone · audit trail is the inventory
The compliance context
Why this matters now, even with the federal stack softening.
The federal methane regime softened twice between 2025 and 2026. Congressional Review Act disapproval of the Waste Emissions Charge implementing rule in March 2025 made the federal methane fee dormant. EPA finalized weakening of the OOOOb/c rule in April 2026, extending the emergency flaring window from 24 hours to 72 hours and other relaxations. Industry savings estimated by EPA at roughly $2.5 billion from 2024 to 2038.
The California disclosure regime did not soften. SB 253, signed in October 2023 and survived its constitutional challenges, requires annual public disclosure of Scope 1, Scope 2, and Scope 3 GHG emissions for U.S. companies with $1 billion or more in revenue doing business in California. CARB adopted the implementing regulation at its February 2026 Board hearing, setting the first reporting deadline at August 10, 2026, covering fiscal year 2025.
For mid-tier upstream operators with California revenue exposure, this is the binding piece of the 2026 disclosure regime. SB 261 (climate-related financial risk disclosure) is in legal limbo, Ninth Circuit injunction November 18, 2025, CARB non-enforcement December 1, 2025. SB 253 is unaffected and continues toward August 10.
Who it applies to
The doing-business-in-California test, applied to upstream.
SB 253 applies to U.S.-organized entities with annual revenue exceeding $1 billion that do business in California. The doing-business test is broad and follows California Revenue and Tax Code definitions. For an upstream operator, the most common qualifying connections look like:
- California marketing, trading, or commercial operations (a desk in Los Angeles, San Francisco, or Sacramento that contracts with California refineries or counterparties).
- California-domiciled subsidiaries or affiliates, even if the operating assets sit elsewhere.
- Crude or NGL sales delivered into California refineries, or product sales above the California-sourced revenue threshold.
- California-based investors or limited partners triggering the doing-business definition (private equity backed operators should check this carefully).
- Legacy California operating assets, retired or producing, including California-domiciled wells, gathering systems, or processing facilities.
The test is broader than most operators initially assume. If you are private and above $1 billion in revenue and you have any of the above connections, you are most likely in scope. Confirm with your tax counsel before August 10.
What you file
FY 2025 Scope 1 + Scope 2, in the GHG Protocol format, by August 10, 2026.
The first reporting cycle covers fiscal year 2025 emissions. CARB accepts data the reporting entity already possesses or already collects, which is the enforcement discretion the February 2026 Board adopted to support good-faith first-year filings.
Scope 1. Direct GHG emissions from sources owned or controlled by the entity. For upstream, this is the largest line item: methane and CO2 from petroleum and natural gas systems (Subpart W categories), CO2 from fuel combustion at generators and compressors, methane from pneumatic devices, vented and flared volumes, fugitive emissions from equipment leaks. The Subpart W inventory is the primary input.
Scope 2. Indirect GHG emissions from purchased electricity, purchased steam, purchased heat, or purchased cooling. Smaller for upstream than for refining or manufacturing, but required. The data lives in vendor invoices and chart-of-accounts entries.
Scope 3. All other indirect emissions in the value chain (purchased goods, transportation, end use of products). Reporting begins in 2027 (covering FY 2026), not August 2026. Operators should be building the data path to Scope 3 now, but the first deadline is Scope 1 + 2 only.
The reporting framework is the GHG Protocol Corporate Accounting and Reporting Standard. CARB has indicated alignment with that framework rather than building a California-specific methodology.
The data infrastructure underneath
A defensible Scope 1 inventory is reconciled across five data sources.
The reason an SB 253 readiness assessment usually surfaces gaps is that no single existing system holds all the inputs. The Scope 1 number lives across five places in the operator's stack, and reconciling them is the work.
SCADA flare and vent metering
High-frequency flare meter data and vent-event timestamps live in the historian (AVEVA PI, Ignition, Cygnet). Reconciling SCADA-measured volumes against Subpart W estimates catches the most common Scope 1 under-count.
Production accounting
Enertia, Quorum, Pak, IFS Merrick. The combustion side of Scope 1 (fuel-burning equipment, generators, compressors) lives partly here, partly in CMMS, partly in the chart of accounts. The reconciliation agent does the cross-walk.
CMMS + chemical inventories
Maximo, MaintainX, IFS, Pak. Process emissions and chemical-injection emissions live in chemical inventory records and equipment maintenance logs. Easy to miss in a spreadsheet build, harder to miss when the data layer is connected.
Power and gas purchase records
Scope 2 (purchased electricity, purchased steam, purchased gas) lives in vendor invoices and chart-of-accounts entries. Smaller line item for upstream operators than Scope 1, but still required under the GHG Protocol framework.
The 90-day path
From May 8 to August 10. Four phases.
For mid-tier operators not yet ready, this is the practical schedule between today and the deadline. Not a sales pitch, just the path.
May to early June 2026
Confirm scope + identify data gaps
Confirm with tax counsel whether the doing-business-in-California test applies to you. Inventory your existing data sources: Subpart W filings, production accounting, SCADA flare/vent metering, chemical inventories, fuel-burning equipment records. Identify the gaps where you don't have a defensible Scope 1 or Scope 2 number yet.
Mid June to early July 2026
Stand up the reconciliation layer
Connect the data sources read-only and reconcile against the GHG Protocol framework. For most upstream operators, the heavy lift is reconciling Subpart W (methane and CO2 from petroleum and natural gas systems) with operational data sources to catch under-counted vented emissions, fugitive sources, and combustion-equipment burn. The work that supports SB 253 also supports your ESG investor reporting and any future federal reinstatement.
Mid July to early August 2026
Generate the inventory + the audit trail
Generate the FY 2025 Scope 1 + Scope 2 inventory in the format CARB requires. The audit trail behind every number should be drillable to source: which SCADA tag, which Subpart W line item, which vendor invoice. The defensibility of the inventory is the inventory.
August 10, 2026
File
File the FY 2025 Scope 1 + Scope 2 GHG inventory with CARB. CARB has signaled enforcement discretion for first-year filings, but the statutory $500K/year exposure exists and compounds. The same data infrastructure will support FY 2026 filing in 2027 and the addition of Scope 3 reporting.
The three-question readiness check
Three questions. Five minutes. Honest answers.
If you answer yes to all three, you are likely ready for August 10. If you answer no to any one, the gap is data infrastructure, not policy. There is still time.
01
Can your CFO produce a defensible FY 2025 Scope 1 + Scope 2 number from existing systems in under 4 weeks?
If yes, you are ahead of the average mid-tier operator. If no, the gap is data infrastructure, not policy. The work between now and August 10 is closing that gap.
02
Is your Subpart W inventory reconciled against your SCADA flare and vent meters?
Most operators discover at least a 5-15% gap when this reconciliation runs for the first time. The gap is the audit-trail risk. CARB will not penalize a good-faith first filing, but the same data feeds your ESG investor disclosure and any future federal regime.
03
Do you have the audit trail drillable to source for every emissions number you would file?
A defensible inventory is one where every Scope 1 line item is traceable to a SCADA tag, a Subpart W entry, a vendor invoice, or a chemical inventory record. The defensibility is the inventory. Spreadsheet builds usually fail this test.
Where WorkSync fits, and where it doesn’t
Data Hub for the reconciliation, the audit trail as a byproduct.
WorkSync's Data Hub reads from your existing emissions data sources read-only: Subpart W reporting feeds, production accounting (Enertia, Quorum, Pak, IFS Merrick), SCADA flare and vent metering (Ignition, AVEVA PI, Cygnet, eLynX), and chemical inventories from CMMS (Maximo, MaintainX, IFS, Pak). The reconciliation agent normalizes these into a defensible Scope 1 + Scope 2 inventory under the GHG Protocol framework. Audit trail is generated as a byproduct of the daily work loop, not as a quarterly project.
For mid-tier operators with California revenue exposure who do not yet have a defensible August 10 filing, this is the fastest path to one. Land FREE with Data Hub for the integration phase. Most deployments produce a first reconcilable inventory inside 30 days, well within the window between today and the deadline.
Where WorkSync is not the right answer: if you have a mature ESG software stack already producing a defensible Scope 1 + Scope 2 inventory and a clean audit trail, you do not need WorkSync for SB 253. We are the answer for operators whose emissions data currently lives in five disconnected systems and a spreadsheet. We tell you that on the discovery call.
Who we are
WorkSync, the data infrastructure behind a defensible filing.
The company
WorkSync
WorkSync's mission is to leverage technology to drive efficiency and safety in field operations. We see a world where there are zero fatalities and engineers never spend time on data entry again.
Two AI products on one Data Hub. WellOPS for field operations. FlowSync for engineering. The Data Hub is the read-only integration backbone that connects to your existing SCADA, ERP, CMMS, GIS, and historian.
Common questions
Does SB 253 apply to my upstream operation?
SB 253 applies to U.S.-organized entities with global annual revenue exceeding $1 billion that do business in California. "Doing business" is interpreted broadly under California Revenue and Tax Code definitions: California-sourced sales above thresholds, California payroll, California property, or active California operations all qualify. For upstream oil and gas, the most common qualifying connections are: California marketing or trading offices, California-domiciled subsidiaries, crude or NGL sales delivered to California refineries, California-based investors triggering the doing-business definition, or California operations tied to legacy assets. If you are a private operator above $1 billion in revenue with any of those connections, you are most likely in scope. Confirm with your tax counsel.
What is the first-year deadline and what has to be filed?
CARB's implementing regulation, adopted at the February 2026 Board hearing, sets a first-year Scope 1 + Scope 2 reporting deadline of August 10, 2026, covering fiscal year 2025. Scope 3 reporting begins in 2027. The reporting framework is the GHG Protocol Corporate Accounting and Reporting Standard. CARB has indicated it will exercise enforcement discretion for the first reporting cycle, accepting Scope 1 + 2 emissions data the entity already possesses or already collects, rather than requiring a from-scratch inventory build for August 2026.
What are the penalties for non-compliance?
CARB has authority to impose administrative penalties up to $500,000 per reporting entity per reporting year for non-filing, late filing, or other failures to comply. The first-year discretion posture suggests CARB will focus on supporting compliance rather than penalizing initial good-faith filings, but the statutory exposure is real and compounds annually.
What about SB 261?
SB 261 (climate-related financial risk disclosure) is the litigated cousin of SB 253. The U.S. Court of Appeals for the Ninth Circuit granted an injunction against SB 261 enforcement on November 18, 2025. CARB confirmed in a December 1, 2025 enforcement advisory that it would not enforce SB 261 against entities for failing to post and submit climate-related financial risk reports by the January 1, 2026 statutory deadline. SB 261 status is unsettled. SB 253 is not affected by the SB 261 litigation and continues toward August 10, 2026.
How does SB 253 interact with EPA Subpart W and the Waste Emissions Charge?
EPA GHGRP Subpart W (greenhouse gas emissions from petroleum and natural gas systems) is the data backbone underneath both the now-dormant federal Waste Emissions Charge (WEC) and the live California SB 253 Scope 1 inventory for upstream operators. Subpart W reporting is still required regardless of WEC status (the implementing rule was disapproved via Congressional Review Act in March 2025; the underlying statute remains). For SB 253 Scope 1, your Subpart W inventory is the primary input. Operators who stood up WEC tracking in 2024 already have most of the data infrastructure needed. The work that survives is the work SB 253 now requires.
What about the OOOOb/c rollback in April 2026?
EPA finalized weakening of the 2024 OOOO methane rule on April 6, 2026, including extending the emergency flaring window from 24 hours to 72 hours and other relaxations. This affects federal methane regulation, not the SB 253 reporting requirement. The federal compliance floor softened; the California disclosure regime did not. For operators with California revenue exposure, the SB 253 obligation is independent of OOOOb/c status and continues toward the August 10 deadline.
How does WorkSync fit into SB 253 readiness?
WorkSync's Data Hub reads from your existing emissions data sources read-only: Subpart W reporting feeds, production accounting (Enertia, Quorum, Pak, IFS Merrick), SCADA flare and vent metering (Ignition, AVEVA PI, Cygnet, eLynX), and chemical inventories from CMMS. The reconciliation agent normalizes the data into a defensible Scope 1 inventory using the GHG Protocol framework. Audit trail is generated as a byproduct of the daily work loop, not as a quarterly project. Land FREE with Data Hub for the integration phase. For mid-tier operators with California exposure who don't yet have a defensible August 10 filing, this is the fastest path to one.
August 10, 2026 · 94 days from May 8
The deadline is fixed. The data infrastructure is the variable.
Land FREE with Data Hub for the integration and reconciliation phase. Most deployments produce a first reconcilable Scope 1 inventory inside 30 days. The same data layer feeds your ESG investor reporting, your existing Subpart W obligations, and any future federal regime that returns.
24-hour reply · 4-week scope + pricing · no procurement committee for the entry tier