Hydraulically fractured well completions on non-exploratory wells would be required to employ “green” completion techniques and/or pit-flaring for both newly fractured wells and existing wells where re-fracturing is performed. Green completions involve installing special equipment that captures and separates gas and liquid hydrocarbons that can then be treated and sold. This equipment may include tanks, gas-liquid-sand separator traps, and gas dehydration. Venting is proposed as an alternative only when pit-flaring poses a safety hazard, when the flow back gas contains high concentrations of nitrogen or carbon dioxide, or when other technical barriers exist.
Fractured exploratory and delineation wells are generally not within proximity to existing gathering lines. Therefore, EPA is proposing the use of pit-flaring for these wells. Again, venting is proposed as an alternative only when pit-flaring is deemed a safety hazard or when flow back gas is noncombustible.
Green completions have been used voluntarily by companies in states such as Wyoming, Colorado, and Utah. However, their technical and economic feasibility is still being evaluated. Many exploration and production companies question EPA’s proposal to apply a “one-size-fits-all” approach to controlling hydraulic fracturing, given the wide range of operations and gas VOC contents across the country. EPA has determined that VOC emissions from wellheads during production operations are very small, and therefore, is not proposing any controls during these operations.
EPA proposes to regulate each newly installed pneumatic device at processing plants, production sites, and other natural gas facilities. Pneumatic devices can be categorized as “high-bleed,” “low-bleed,” and “no-bleed.”
- High-bleed – a device that releases more than 6 standard cubic feet per hour (6 scfh) of gas
- Low-bleed – a device that releases less than or equal to 6 scfh of gas
- No-bleed – a device that uses a power source other than pressurized natural gas, such as compressed instrument air, and therefore releases no gas
EPA proposes that natural gas processing plants would be subject to a zero VOC emission standard by installing only no-bleed (or non-gas driven) controllers. No-bleed controllers require an existing electrical service to power an instrument air compressor.
Therefore, EPA is proposing no-bleed controller installation at processing plants. At facilities other than natural gas processing plants, where electric power is not readily available, EPA is proposing the installation of low-bleed controllers.
The proposed regulations exempt devices requiring high-bleed controllers for specific reasons, including operational requirements and safety concerns due to their actuation response time or other operating characteristics.
EPA proposes to regulate both centrifugal and reciprocating compressors located anywhere between the wellhead and the city gate as VOC emission sources. Each newly constructed and replaced compressor would be an affected unit and would be subject to the proposed requirements.
As proposed, centrifugal compressors must be equipped with dry seal systems, as opposed to wet seal systems. EPA notes that it may allow wet seals if vented to closed vent systems and control devices.
Reciprocating compressors would need to meet operational standards, including the replacement of the rod packing every 26,000 hours of use. This would require monitoring of the hours of operation for each affected compressor. However, EPA is seeking comment on a leak threshold as a basis for rod packing replacement and the appropriateness of a fixed replacement frequency.
EPA proposes to regulate new and modified storage vessels with condensate throughput ≥ 1 barrel (bbl) per day or crude oil throughput ≥ 20 bbl per day. These tanks would be required to meet a 95% control efficiency using a vapor recovery unit (VRU) or a flare to control working, breathing, and flashing losses.
EPA is not proposing any controls or operational standards for storage vessels with condensate throughput < 1 bbl per day or crude oil throughput < 20 bbl per day.
Several companies are concerned with the low condensate throughput threshold, given the wide range of liquid VOC contents across the country. Additionally, there is a concern that vendors will not be able to meet the increased demand of control equipment installations that will be required, which could result in facilities operating out of compliance until control equipment becomes available.