reduction

The Methane Guiding Principles, a voluntary partnership of oil and gas companies with 22 signatories at the time of writing, has identified best practices for methane emission reduction in eight areas, summarized in table 1.6. The partnership also published best-practice guides, which provide a summary of current known mitigations, costs, and available technologies to help those responsible for developing methane management plans.14

In general, methane emissions can be significantly reduced by implementing a series of technical and operational improvements to oil and gas activities. For instance, Beck et al. (2020) and the IEA (2020a) mention instrument air systems to replace pneumatic controllers to reduce venting, vapor recovery units installed on crude oil and condensate storage tanks, introducing leak detection and repair programs to significantly cut fugitive emissions, and applying the best available

TABLE 1.6 Methane Guiding Principles: Best practices for methane emissions reduction

PRIORITY AREA BEST PRACTICES

Measurement and reporting of GHG emissions • Develop a standardized industry-level data management system.

Engineering design and construction • Use electric, mechanical, or instrument air-powered equipment where possible (including pneumatic controllers, pumps, and engines). • Have centralized and consolidated facilities where possible. • Use pipelines for liquid and gas takeaway. • Recover natural gas for beneficial use where possible. • Flare or combust natural gas when recovery is not possible. • Consider the use of alternative low-emission equipment/process. • Consider the use of alternative low-maintenance equipment/process.

Flaring

• Keep an accurate inventory of flaring activity. • Prevent flaring by designing systems that do not produce waste gases. • Recover waste gases as products to be sold. • Inject waste gases into oil or gas reservoirs. • Find alternative uses for flared gases, such as generating electricity. • Improve the efficiency of combustion when gases have to be flared. • Track progress in reducing flaring and venting. Energy use • Keep an accurate inventory of where natural gas is used as fuel. • Use electrical power or pneumatic power using compressed air or nitrogen. • Improve the energy efficiency of gathering operations and other equipment. • If natural gas needs to be used, improve the efficiency of fuel combustion. • Track progress in reducing fuel use. Equipment leaks • Keep an accurate inventory of emissions from equipment leaks. • Conduct a periodic leak detection and repair program. • Consider using alternative monitoring programs. • Replace or eliminate components that persistently leak. Venting • Keep an accurate inventory of venting activity. • Alter physical systems and operating practices to reduce venting. • Recapture gas where possible. • If methane needs to be released, flare it rather than venting it. • Track progress in reducing venting. Pneumatic devices • Keep an accurate inventory of pneumatic controllers and pumps powered by natural gas. • Replace pneumatic devices with electrical or mechanical devices where practical. • If pneumatic devices are used, eliminate emissions by using compressed air rather than natural gas to power them. • If using devices powered by natural gas is the best option, replace high-bleed controllers with alternatives with lower emissions. • Include pneumatic devices in an inspection and maintenance program, and report emissions from these devices in an annual inventory.

TABLE 1.6, continued

PRIORITY AREA BEST PRACTICES

Operational repairs For operational repairs, • Perform periodic leak-detection surveys; • Repair leaks as soon as practical; • Check that repairs have been successful; • Keep track of repairs that have not been carried out; and • Keep and analyze records of leaks and repairs. For routine maintenance and repairs, • Use pumpdowns for pipelines and large vessels; • Minimize the volume that must be depressurized; • Use vapor-recovery units when pigging; • Avoid emissions by, for example, using hot taps to make connections to pipelines, carrying out nonintrusive inspections, and coordinating repairs and maintenance; and • If venting is necessary, flare the vented gases.

Continual improvement • Commit to a program of methane management. • Improve methane reduction capabilities for preventing, identifying, and repairing leaks, and using effective engineering and design. • Set strong methane-reduction targets. • Report methane-reduction efforts and results. • Integrate methane management into the company culture.

Source: Based on Methane Guiding Principles, “Best Practice Guides” (https://methaneguidingprinciples.org/best-practice-guides/).

technologies (such as double mechanical seals on pumps, dry gas seals on compressors, and carbon packing ring sets on valve stems). The IEA (2020a) estimates that, if all these options were deployed across the oil and gas value chain, about 75 percent of the 2019 estimated 82 Mt of methane emissions from oil and gas operations could be avoided.

Global methane emission volumes

The concentration of methane in the atmosphere is about two-and-half times greater than preindustrial levels and is increasing. However, estimates of global methane emissions are subject to a great degree of uncertainty. The most comprehensive recent estimates are provided by the IEA (2020c) and put global methane emissions at 570 Mt, 40 percent of which originated from natural sources and 60 percent from human activity (“anthropogenic” emissions; figure 1.7).15 The largest source of anthropogenic methane emissions is agriculture, responsible for about a quarter of the total, closely followed by the energy sector, which includes emissions from coal, oil, natural gas, and biofuels (IEA 2020c).

This uncertainty involves also, specifically, the estimates of oil and gas methane emissions, despite the emergence of new satellite data and other measurement tools. Several factors contribute to this uncertainty (IEA 2020b):

• Reporting companies mostly rely on average emission or activity factors, rather than on measured levels. The emission factors, derived from limited data, may not be applicable to all oil and gas facilities.

• Reported emissions may not be representative of those of the industry as a whole: companies that actively report methane emissions levels are generally the “best performers” in their peer group.

• Top-down studies misallocate emissions to the oil and gas sector, attributing to it methane emissions that in fact come from other sources such as coal, agriculture, or natural sources.