On December 2, 2023, the U.S. Environmental Protection Agency (EPA) announced the final rulemaking regarding methane (CH4) and volatile organic compounds (VOC) emissions from oil and natural gas industries. The new final rules cover:
- 40 CFR 60 Subpart OOOOb—Standards of Performance for Crude Oil and Natural Gas Facilities for which Construction, Modification or Reconstruction Commenced After November 15, 2021 (NSPS OOOOb)
- 40 CFR 60 Subpart OOOOc—Emissions Guidelines for Greenhouse Gas Emissions from Existing Crude Oil and Natural Gas Facilities (EG OOOOc)
The NSPS OOOOb rules will become effective after 60 days of publication in the Federal Register.
Although the OOOOb rules will become effective in early 2024, they apply to wells and facilities that were constructed after December 6, 2022.
NSPS OOOOb are federal emission regulations meant to reduce VOCs and CH4 emission from new onshore oil and natural gas facilities.
EG OOOOc are guidelines that states must implement in their state air quality regulations for existing oil and natural gas facilities. States have 2 years to submit their plans to EPA. The states’ OOOOc rules must make existing facilities comply within 3 years of EPA approval. So, it could take 5 years to implement OOOOc rules in a state.
This discussion addresses the proposed rules in NSPS OOOOb.
Below are the OOOO rules and applicability dates.
OOOOb Expands Reach: New and Old Sources
The following emission sources are included in OOOOb.
- Associated gas from oil wells
- Completions of hydraulically fractured wells
- Centrifugal compressors
- Wet seals
- Dry seals – new OOOOb source
- Reciprocating compressors
- Fugitive emissions from equipment leaks
- Liquids unloading – new OOOOb source
- Pneumatic controllers using natural gas
- Pneumatic pumps using natural gas
- Storage vessels aggregation at tank battery
- Super-emitters of methane – new OOOOb source
- Sweetening units
- Well closure requirements – new OOOOb requirement
Tank Battery Control: New Group Rules
The OOOOb limits for storage tanks apply to the combined emissions from the group of tanks at a tank battery.
This is a major change from NSPS OOOO and OOOOa that applies the emission standards on an individual tank basis.
OOOOb imposes a limit on CH4 emissions from tank batteries.
The following are the emission limitations on storage vessels at a tank battery:
- 6 ton per year (tpy) of VOCs
- 20 tpy CH4 (approximately 945,885 standard cubic feet of methane per year)
A tank battery is defined as a group of all storage vessels that are manifolded together for liquid transfer. A tank battery consists of one or more tanks.
Tank batteries emitting equal to or greater than 6 tpy VOCs or 20 tpy CH4 must use a control device to reduce VOC and CH4 emissions by 95% or greater.
Tank Battery Legally and Practical Emission (LPE) Limits
Tank battery facilities with emissions less than 6 tons VOC per year (tpy) or less than 20 tpy of CH4 can avoid OOOOb applicability if they comply with an air permit with legally and practicably enforceable (LPE) limits. For OOOOb, EPA expanded the requirements for air permits to have valid LPE limits on storage tank PTE emissions. NSPS OOOO and OOOOa do not have these stringent requirements.
To qualify for LPE under OOOOb, the air permit must include production limits (e.g., barrels oil per year) performance testing of emission controls, ongoing monitoring, recordkeeping and reporting to demonstrate compliance.
By securing LPE limits for their tank batteries, operators can significantly reduce their regulatory burden, exempting themselves from the complex emission controls, testing, monitoring, and reporting demands of NSPS OOOOb.
State air permits will need to be updated to include the OOOOb legally and practicably enforceable limits.
Storage Tank Modification Trigger
If a storage tank battery triggers a modification under OOOOb, then all the tanks must comply with OOOOb requirements for emission controls, testing, monitoring, recordkeeping, and reporting. The following triggers an OOOOb modification for storage tanks.
- A storage tank is added to an existing tank battery.
- Replacement of one or more tanks increases total storage capacity (bbls) of a tank battery.
- A new well or new operation increases production (including wells hydraulic fractured or refractured)
- For compressor stations and gas processing facilities, the tank battery throughput exceeds the amount estimated in most determination of potential VOC and methane emissions.
Storage Tank Reconstruction Trigger
If a storage tank battery triggers reconstruction under OOOOb, then all the tanks must comply with OOOOb requirements for emission controls, testing, monitoring, recordkeeping, and reporting. The following triggers reconstruction for storage tanks:
- One half or more of storage tanks are replaced in an existing tank battery that consists of more than one storage tank.
- The fixed capital cost of the new tanks exceeds 50% of the fixed capital cost required to construct a new tank battery and it is technologically and economically feasible to meet the applicable standards (ref: 60.15).
Vapor Recovery Unit (VRU)
OOOOb specifically lists vapor recovery units (VRUs) as emission control devices that venting from natural gas driven pneumatic pumps can use to make the devices a zero-emission source.
Methane emissions from storage tanks that are recovered by a VRU are not included in the PTE determination for whether OOOOb applies to the tank battery. This requires the tanks to be equipped with covers (e.g., hatches, pressure relief, etc.) and use of closed vent system piping to send vent gas to the control device. The covers and closed vent system must meet OOOOb requirements.
Flares can be used as emission controls for associated gas, storage tanks, compressor seal leaks, glycol reboiler vents, natural gas pneumatic devices and facility blowdowns.
The requirements for flares used as emission controls to comply with OOOOb have been expanded.
Some of the requirements for flares in the proposed rule includes:
- Comply with 40 CFR 60.18(b).
- Monitoring to ensure that a pilot flame always burns.
- Meet specified net heating values (BTU/scf) of gas combusted – depending on the type of flare.
- Operate with no visible emissions
- Use a continuous burning pilot flame
Enclosed Combustion Devices
Enclosed combustion devices (ECD) are another control device used for associated gas, storage tanks, compressor seal leaks, glycol reboiler vents, natural gas pneumatic devices and facility blowdowns.
To comply with OOOOb, facilities can use ECDs models that have been performance tested by the manufacturer using OOOOb prescribed methods.
If an ECD model is used to comply with OOOOb and the model is not OOOOb tested by the manufacturer, the operator must conduct and initial and periodic (every 60 months) or to establish a new operating limit) performance test at the facility to prove compliance with the control efficiency.
Some of the requirements for ECDs in the rule include:
- Operate the ECD with no visible emissions
- Use a continuous burning pilot flame
- Monitoring to ensure a pilot flame always burns
- Operate at a minimum temperature of 760°C, if the control device demonstrated, during the performance test, that the combustion zone temperature indicates destruction efficiency.
- Meet specific net heating values (e.g., BTU/scf) of vent gas combusted.
Super-Emitters of Methane Tracked – New Emission Concern
Super-emitters of methane (CH4) are a new category of targeted emissions in OOOOb. A super-emitter event is defined as emissions of 100 kg/hr or more of CH4 from an oil and gas facility that is detected using remote detection methods.
Emissions of 100 kg/hr of methane equal about 5,213 scf/hr of methane.
For this effort, EPA is collaborating with third-party notifiers who have technical expertise in remote methane detection. These notifiers will use satellite detection, remote-sensing equipment on aircraft, and mobile monitoring platforms to monitor and report on super-emitter events.
The general procedure appears to involve:
- Third-party notifiers that detect super-emitter events will report data to the EPA.
- EPA will review the data from reported event and decide whether to notify the company that operates the subject facility.
- If the notified company does not have an oil and gas facility within 50 meters of the latitude and longitude of the event, the company will inform the EPA and that will end the investigation for the company.
- If the notified company has an oil and gas facility within 50 meters of the latitude and longitude of the event, the company must investigate to determine the source of the event, corrective actions taken, and conduct surveys to demonstrate super-emitter event has been corrected.
- The company must submit its findings to the EPA using the EPA’s Super-Emitter Program Portal within the prescribed timeline in OOOOb.
Super-emitter reports will be publicly available on the USEPA Super-Emitter website.
Well Closures Targeted– New Emission Source
The EPA has identified abandoned and unplugged wells as a significant source of CH4 emissions. To reduce CH4 emissions, the rule requires a well closure plan be submitted to the EPA. The plan will include steps to plug the wells, documentation of financial assurance for well closure and a schedule for closure activities.
After a well is closed, the operator must perform a leak survey using Optical Gas Imaging (OGI) to confirm that there are no emissions. If any emissions are detected, corrective actions must be taken to stop them.
The OOOOb standards for well completions are like the existing NSPS OOOO and OOOOa.
Well Liquids Unloading Practices – New Emission Source
The rule adds liquids unloading vent gas to the list of emission sources.
The rule requires use the specified best management practices to minimize venting of methane and VOC emissions. If best management practices are not used, then reduce unloading methane and VOC emissions by 95%.
Cimarron has portable and permanent flares and enclosed combustion devices that can be used as emission control devices for well liquids unloading venting. This includes equipment for sale or rent.
Associated Gas from Oil Wells – New Emission Source
The rule requires associated gas from oil wells to be sent to a sales pipeline, fuel gas system or reinjected into a well. There is no definition of an oil well in the regulation. Most operators classify their wells (oil, natural gas) based on the state oil and gas mineral regulator definition.
If these options are demonstrated to be infeasible, the gas must be sent to a control device (e.g., ECD, flare) with at least 95% control efficiency. A professional engineer or other qualified individual must certify the technical or safety reasons for the infeasibility.
The rule gives approximately 2 years to comply.
Wet Seal Centrifugal Compressors
OOOOb requires wet seal centrifugal compressors to capture and route emissions from the wet seal fluid degassing system to a control device or to a process.
Self-contained wet seal centrifugal compressors vent rate must not exceed 3 standard cubic feet per minute (scfm) per seal. Self-contained wet seal compressors, in general, send their gas back to the system process. If the leak exceeds 3 scfm per seal, the seal must be repaired. A confirmatory leak measurement is required after repair.
The wet seal flow rate must be measured on or before 8760 hours of operation.
Flow rate measurements can use a temporary or permanent flow meter or a high-volume sampler.
Centrifugal compressors located at a well site are exempt from these rules.
Dry Seal Centrifugal Compressors – New Emission Source
Dry seal centrifugal compressors are a new emission source regulated by OOOOb. Dry seal centrifugal compressor gas vent flow rate must not exceed 10 scfm per seal. If the leak exceeds 10 scfm per seal, the seal must be repaired. A confirmatory leak measurement is required after repair.
Dry seal compressor flow rate must be measured on or before 8760 hours of operation. Flow rate measurements can use a temporary or permanent flow meter or a high-volume sampler.
Dry seal compressors can elect to capture and route emissions with a control device that is at least 95% efficient (e.g., ECD or flare).
Centrifugal compressors located at a well site are exempt from these rules.
Reciprocating compressors rod packing leaks cannot exceed 2 scfm per individual cylinder. If the leak exceeds 2 scfm per cylinder, the rod packing must be replaced or repaired. A confirmatory leak measurement is required after repair. Follow up measurement of the rod packing seal required after repair/replacement.
As an alternative to periodic measurement, the rod packing seal can be sent to a closed vent system to a process (e.g., fuel gas system) or to an emission control device that is at least 95 efficient (e.g., ECD or flare).
Annual flowrate monitoring of rod packing seal leaks is required. Seal flow rate measurements must be conducted on or before 8760 hours of operation. A temporary meter or high-volume sampler may be used to quantify leak rates.
Reciprocating compressors located at a well site are exempt from these rules.
Leak Detection and Repair (LDAR) – Well Sites
The rule expands requirements for leak detection and repair (LDAR) of fugitive emissions from equipment leaks.
The new rule includes procedures to obtain approval of alternate leak monitoring systems and for continuous monitoring systems for leaks. At a later date, broadly applicable methods and approval letters will be posted at: https://www.epa.gov/emc/oil-andgas-approved-alternative-test-methods-approvals.
The following tables show leak monitoring proposed for new and modified sites that use traditional LDAR methods (e.g., OGI camera, Method 21).
Well sites and compressor stations on the Alaska North Slope would be subject to annual monitoring using OGI.
Optical Gas Imaging (OGI) EPA Protocol – Appendix K
The rule includes final updates to the protocol using optical gas imaging (OGI) for LDAR monitoring for methane and VOC leaks. The protocol is called Appendix K to 40 CFR part 60, “Determination of Volatile Organic Compound and Greenhouse Gas Leaks Using Optical Gas Imaging.” The procedure has requirements for performance of IR camera, operator training and audits, monitoring plans, recordkeeping, and development of response factors.
Currently, the use of Appendix K for leak monitoring only applies to gas processing facilities. The EPA has stated that other facility types may be required to use Appendix K in the future.
Cimarron’s VOC detection via continuous visual automation meet the requirements of Appendix K for OGI LDAR monitoring.
Natural Gas Pneumatic Controllers
The rules apply to the collection of natural gas-driven pneumatic controllers at a facility. OOOO and OOOOa lists each natural gas-driven pneumatic controller as an affected emission source.
OOOOb requires all new pneumatic controllers to have zero methane and VOC emissions, except for sites in Alaska that do not have power. Routing pump natural gas to a process is allowed and must use a closed vent system to send gas to a system. Self-contained natural gas-driven pneumatic controllers can be used to meet the zero emissions requirement.
Natural gas-driven pneumatic controllers that function as emergency shutdown devices and pneumatic controllers that are not driven by natural gas are exempt.
A modification of natural gas pneumatic controllers occurs when more than 50% of the controllers are replaced at a facility. When a modification of the controllers is triggered, OOOOb applies to all the natural gas pneumatic controllers.
OOOOb applies to the collection of natural gas-driven diaphragm and piston pumps at a facility.
Pumps not driven by natural gas and pumps that operate for less than 90 days per calendar year are exempt. Pneumatic pumps that use compressed air are not regulated by this rule. A lean glycol circulation pump (e.g., Kimray) that uses energy exchange with rich glycol from the contactor is exempt from the rules.
New pneumatic pumps must have zero methane and VOC emissions if:
- The site has access to electrical power.
- The site does not have electrical power and it operates 3 or more natural gas driven diaphragm pneumatic pumps.
Zero emissions can be accomplished by sending the discharge gas to a process (e.g., fuel system, suction of a compressor) and not venting or flaring the gas.
For sites without electricity that have fewer than 2 natural gas driven diaphragm pumps, the
- Send gas to a vapor recovery unit (VRU)
- Send gas to a control device that is at least 95% efficient (e.g., flare, ECD)
A facility does not have to install an ECD, flare or VRU, just to comply with OOOOb requirements for pumps.
Written certification by a qualified professional engineer or in-house engineer is required to justify the technical infeasibility of sending pump emissions to a process or a control device.
Adding one or more natural gas-driven pumps to a site constitutes a modification. Reconstruction is triggered whenever greater than 50 percent of the number of existing onsite natural gas-driven pumps are replaced. This means that OOOOb applies to all the natural gas pneumatic controllers after a modification or reconstruction.
Recordkeeping and Reporting
The rules have numerous requirements for recordkeeping and reporting. Consult the rules for details.
Annual reports must use the format supplied by EPA. Submission of the annual reports will use EPA’s CEDRI website. The reporting requirements will increase the amount of time needed to complete the annual report. Annual reports are due 90 days after the compliance period (to be determined).
Summary and Conclusions
The U.S. Environmental Protection Agency (EPA) has announced new regulations regarding methane and VOC emissions from oil and natural gas industries. The new rules cover:
- NSPS OOOOb: Standards of Performance for Crude Oil and Natural Gas Facilities for which Construction, Modification or Reconstruction Commenced After December 6, 2022.
- EG OOOOc: Emissions Guidelines for Greenhouse Gas Emissions from Existing Crude Oil and Natural Gas Facilities.
NSPS OOOOb is a federal new source performance standard designed to reduce volatile organic compounds (VOCs) and methane (CH4) emissions from new onshore oil and natural gas facilities. EG OOOOc are guidelines that states must follow in their state air quality regulations for existing oil and natural gas facilities.
NSPS OOOOb includes emission standard for associated gas from oil wells, completions of hydraulically fractured wells, centrifugal compressors, reciprocating compressors, fugitive emissions from equipment leaks, liquids unloading, natural gas pneumatic controllers, natural gas pneumatic pumps, tank battery storage tanks, super-emitters of methane, and sweetening units.
The rules take effect 60 days after publication in the Federal Register.
Cimarron – Who We Are
With decades of operating history and innovation across our trusted brands, Cimarron provides technology-driven emissions management solutions for the global energy system.
Our leading-edge products, services, and real-time monitoring systems reduce emissions, optimize operations, ensure regulatory compliance, and drive sustainability progress for our customers operating in oil & natural gas production, energy storage & distribution, renewables & biogas, coal mine methane, and certain industrial end markets.
Cimarron boasts a collection of well-established technologies which have been assembled and innovated from trusted industry brands. Our vast global experience, spanning tens of thousands of equipment installations, serves as a testament to our ability to achieve success in every project upon which we embark.
Cimarron headquarters in Houston, Texas with approximately 550 employees serving our global customer base. In addition to being present in all major regions in the U.S., Cimarron operates across more than 45 countries around the world. We support our customers from sales, engineering, manufacturing, and field service locations across the United States, Italy, India, England, and the United Arab Emirates, further supported by our network of international partners.