Flare stacks and combustors are used by the oil and gas industry to burn off any methane waste and volatile organic compound (VOC) emissions resulting from the processes of drilling, collecting, and storing of oil and natural gas.
Methane and natural gas are more potent than CO2 as greenhouse gases (GHG), so burning methane/natural gas off to less-harmful gases is a better option than venting it directly into the atmosphere when upset conditions require a flaring event.
There are some key differences between a flare stack and a combustor. Flares are very tall and produce a flame at the top that is visible for miles around. Combustors, on the other hand, are much shorter, enclose the flame, and act as an incinerator. The efficiency of a flare during windy conditions can be as low as 50% whereas an enclosed combustor experiences little effects from the wind. There is also new evidence to suggest that combustors are both more efficient than flares and more desired for surrounding communities.
To reduce harmful emissions from oil and gas production sites, the United States Environmental Protection Agency (EPA) issued rule 40 CFR Part 60 Subpart OOOO (Quad O) in 2015. Since then, several updates to this environmental regulation have been issued.
For this blog, we focus on the Quad O flare gas monitoring regulations for oil and gas operations.
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Quad O regulations apply to new, modified, or reconstructed sources built after August 23, 2011. For help in determining whether Quad O compliance is required for your operation, see Is the Equipment or Process You Manage Affected by Quad-O? |
Quad O Updates
Two significant updates to the Quad O rule, labeled OOOOb and OOOOc, became effective May 7, 2024. In update OOOOb, new source performance standards (NSPS) call for phasing out the flaring of gas as a standard practice.
Instead of flaring or combustion, the Code of Federal Regulations Quad Ob now requires that new oil and gas facilities redirect excess gases to a natural gas sales line, to storage vessels, or to on-site power equipment to be used as fuel. The process of capturing this gas instead of flaring it has various names: “reduced emissions completion (REC)” “flareless completions”, “green completions”, and “closed loop completions”.
However, there are emergencies where equipment or valve malfunction/failure causes a pressure build-up in the system that must be released. In these instances, Quad O recognizes that it’s better to flare gas to release the pressure than allow a catastrophic event that could release natural gas directly into the atmosphere or jeopardize the health and safety of workers. In these cases, Quad O requires applicable flares and combustors to improve their combustion efficiency.
Keep in mind that flares are used across many oil and gas operations, not just at well sites. For instance, OOOOb states that any tank batteries emitting equal to or greater than the limit must use a control device to reduce emissions by 95% or greater. In some cases, this will be a Vapor Recovery Unit in addition to a flare or combustor for emergency flaring.
In update OOOOc, flares at pre-existing well sites are now required to achieve a 95% reduction in methane. So along with a general move toward reducing the use of flares (not the existence of them as part of emergency procedures), when they must be used, these flares must perform optimally toward the overall goal of reducing methane emissions.
Also under update OOOOc, consistent flaring is permitted for pre-existing wells with documented methane emissions of 40 tons per year or less, so long as that gas is routed to a flare or control device that achieves a 95% reduction in methane.
To fully comply with the updated Quad O regulations, operators must install a method to harness produced gas, either to sell or fuel equipment on-site. However, they still need to install combustion devices (flares or combustors) at well sites to accommodate upset or safety flaring events. These flares are expected to be more efficient than those in the past so that gas emissions are combusted more completely.
To ensure that the flares or combustors comply with Quad O regulations, they need to be equipped with monitoring devices to record and report any flaring events. Operators need to monitor the flow of gas during emergency flaring events (flare or combustor gas) and also the gas that is redirected to be captured/stored (vent gas at tank batteries), sold (sales gas), or used as fuel (fuel gas).
Fox Thermal’s mass flow meters can help oil and gas facilities meet the Quad O compliance reporting requirements for flare emissions:
With the updated Quad O emissions standards, record-keeping will become more necessary during flaring events. The Fox Thermal FT4X gas flow meter can make this transition far easier for operators.
The FT4X comes equipped with a data logger that offers long-term record keeping (up to 7-year history), that includes information about the gas composition and whether the composition has been changed and when, as well as flow data over time, and when or if any alarms have been triggered. This data is highly valuable for operators to keep them informed on what is happening in their process so they can act quickly to minimize emissions.
In addition to more strict flare gas emissions standards, Quad O establishes a new Super Emitter program.
In this program, third-party investigators can be certified to visit oil and gas production sites and measure emissions data. These investigators look for sites that are failing to meet the new, or current, emissions standards and requirements and will send reports directly to the EPA with details on the data they have collected. The EPA will then contact the owners of the site where the emissions were detected and require them to perform an investigation and fix the issue.
The Super Emitter program means that site owners must take proactive measures to reduce emissions by choosing efficient control devices that lead to a reduction in overall emissions. It is also in their best interest to collect and retain as much data as possible to back up their claims about emissions reduction over time.
A gas flow data logger, such as the one on the FT4X will provide the data needed to back up their claims and submit to EPA if an investigation is warranted.
Fox Thermal's FT4A and the FT4X flow meters are designed specifically for oil and gas applications such as monitoring flare gas and combustor gas. Fox Thermal mass flow meters do not require additional temperature and pressure measurements for correcting volumetric flow rates to standard conditions and provide accurate measurements even at low-velocity flow, such as in flare applications.
Our flow meter features that are particularly beneficial for flare gas applications include the DDC-Sensor™, Gas-Select X®, and CAL-V™, as well as the advanced data logger.
The Gas-Select X® feature provides accurate measurements across changing gas compositions. Every FT4X and FT4A flowmeter is pre-programmed with a mixed gas menu and oil & gas menu or create a custom gas mix specifically for your application.
CAL-V™ allows operators to show records of the accuracy of the meter over time. If the operator includes regular CAL-V™ tests in their maintenance procedures and produces a CAL-V™ calibration validation certificate after each regular test, they have a paper trail proving that the meter is providing accurate flow measurement over time.
Sites that install the model FT4X with the data logger don't even need to print the certificates each time they perform the CAL-V™ test. Instead, they can show the log of all tests performed and the result in the log with date/time stamps of each time the test was performed.
Fox Thermal’s flare gas flow meters can not only help your company meet the EPA Quad O emissions reduction requirements but also support reducing your impact on the environment and improving your bottom line.
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