The largest oil and gas major in the US announced a new plan this week to reduce and regulate methane emissions across “all phases of production.”
ExxonMobil is sharing its internally adopted plan in the hopes that industry regulators and other oil and gas companies will broadly implement tighter emission mitigation practices that it says are cost-effective. The call for stricter policies comes as the industry faces increased pressure from public stakeholders, investors, and governments to address climate change by reducing greenhouse gas emissions.
“ExxonMobil has been applying the principles of this framework to our oil and natural gas operations for several years, resulting in improvements that demonstrate what’s practicable and achievable,” said Darren Woods, chairman and chief executive officer of ExxonMobil.
“We offer this blueprint to companies across our industry as they consider how to make improvements to reduce the sector’s methane emissions. Our industry has developed high-tech advances to curb emissions, and we also hope this framework will be helpful for governments as they develop new regulations,” added Woods.
ExxonMobil’s initiative is based largely on a voluntary emissions reduction program that was launched in 2017 through its US-shale subsidiary, XTO. The now expanded program prioritizes monitoring technologies, the mitigation of wellhead venting, and the replacement of production equipment components that have “a high-leak potential” which includes commonly used pneumatic devices that rely on venting methane to function.
“More comprehensive than current federal rules, the proposed regulations would apply to new and existing sources,” the company said in a press release. ExxonMobil also reported that following these standards has led to a 20% reduction in XTO’s methane emissions since 2016 and has put the company as a whole on track for a 15% reduction.
ExxonMobil offered details on the four pillars of its regulatory proposal.
Leak Detection and Repair
A major source of the industry’s unintentional emissions, or leaks, involve production and process equipment across the oil and gas infrastructure landscape. Typical equipment components where fugitive emissions can occur are valves, screwed connections, flanges, open-ended lines, and pump seals.
- Establish a “leak detection and repair” (LDAR) program.
- Leaks detected should be repaired when possible, or entered into a system for correction as soon as practicable (e.g., within 30 days).
- LDAR coverage should be repeated periodically (e.g., at least once per year).
- A regulating authority should also consider whether to:
- Provide exemptions for low producing or “marginal” wells (e.g., less than 15 BOE/D)
- Develop a specific listing of equipment and components to be covered
Minimization of Wellhead Venting
All unconventional wells that are hydraulically fractured are brought on line through the flowback process. As excess water and sand is removed from the stimulated reservoir, flowback fluids are mixed with natural gas that can vent to the atmosphere if not controlled.
- New hydraulically fractured wells should follow reduced emissions completion (REC) procedures.
- REC separators should be used so the gas can be routed for separate collection and into sales lines or other production uses, once conditions allow.
- Collected gas can be combusted if other uses are infeasible, or for safety reasons.
Operational Equipment Controls
Pneumatic controllers are valves that are used throughout industrial operations to control pressure, fluid levels, temperature, flow rate, and other processes automatically. Natural gas-powered pneumatic controllers directly release or “bleed” methane as part of their intended function. ExxonMobil’s proposed regulatory framework calls for the elimination of continuous high-bleed pneumatic (HBP) control devices, except in cases where they are required for process or safety conditions.
- Replace HBPs on existing facilities.
- A regulating authority should consider an appropriate phaseout period given its operational context (e.g., within 3 years).
- Do not use HBPs on new facilities.
- Use no or low-bleed devices where technically feasible.
- Use mechanical or electric control where possible when electricity is available.
- Conduct periodic pneumatic-controller maintenance, for example when conducing LDAR program.
Record Keeping and Reporting
Quantifying methane regulations has been a challenge in the past but technology and dedicated research has solved many of the tallest hurdles. Documenting the volume of methane that is released at any given site is also critical to establishing baselines and enforcing regulatory policies. ExxonMobil has created a comprehensive list of what oil and gas operators need to keep track of to support those goals.
- Total methane emissions: Each operator should report annually the total methane emissions from its operated assets.
- LDAR program: Document and annually report results of inspections.
- Completions and flowback: Report to agency the anticipated dates of upcoming completions, within 2 days of each process, to allow opportunity for direct inspection.
- Manual liquid unloading: Document and report annually dates, times, durations, and estimated volumes of any venting that occurred.
- Pneumatic controllers: Document and annually report the type and bleed rates of pneumatic controllers the company has in operation.
- Pneumatic pumps: Monitor, document, and annually report on pumps, vapor recovery units (VRUs), and combustion devices as part of LDAR program.
- Compressors: Monitor, document and annually report on compressors, seals, VRUs, and combustion devices as part of LDAR program.
- Storage tanks: Document installation and proper operation of gas capture systems as required by regulations (e.g., a VRU or combustion device) for storage vessels, for a beneficial use to achieve at least a 95% reduction in methane emissions.
- Pipeline blowdowns: Document and report annually on the number of blowdown events (i.e., planned and unplanned releases), as well as the estimated volume of gas emitted from such events.