Methane is a highly potent greenhouse gas with more than 80 times the warming power of carbon dioxide over a 20-year period. It is the second-highest greenhouse gas emitted globally, with annual emissions of 600Mt, and roughly 60% of these emissions are anthropogenic. The majority of these anthropogenic emissions are from the agriculture sector and the oil and gas industry.
The latest IPCC assessment report published on 9th August 2021 highlights the urgent action required on climate change and reducing methane emissions is a hugely important lever in efforts to limit the increase in average global temperatures to below 1.5oC from pre-industrial baseline.
The Oil and Gas Methane Partnership (OGMP) is a Climate and Clean Air Coalition (CCAC) initiative led by the UN Environment Programme (UNEP), in partnership with governments, the Environmental Defense Fund, and leading oil and gas companies. Companies that have agreed to join this venture have committed to measuring, reporting and reducing methane emissions from their operations. The goal of this voluntary initiative is to deliver a 45% reduction in the industry’s emissions by 2025, and 60-75% reduction by 2030. The OGMP company members include majors such as BP, Shell, Equinor, ENI and Total.
The International Energy Agency (IEA) estimates that around ¾ of emissions can be reduced with existing technology. The main sources of methane emissions from the oil & gas sector and methods to reduce these emissions are laid out in a set of 9 technical guidance documents published by the OGMP.
There are various design changes that can be made to existing facilities to reduce methane pollution. Pneumatic devices (like liquid level controllers, pressure regulators and valve controllers) that are powered by pressurised natural gas often bleed during operations. By replacing high-bleed devices with low-bleed devices, or retrofitting high bleed devices to capture these emissions, it is possible to significantly decrease methane lost from facilities. Other design changes include using flash tank separators instead of methane as a stripping gas when regenerating glycol for gas dehydration or replacing “wet” seals in centrifugal compressors with dry / mechanical seals. Facility and equipment design has a huge impact on methane emissions, and selecting alternative designs and making modifications can bring down emissions.
Oil and gas facilities can also choose to invest in Vapour Recovery Units (VRUs), so that methane can be captured and compressed instead of being released into the atmosphere. VRUs can be installed to capture methane in a range of scenarios including capturing vapours from storage tanks.
On oil facilities where there is no market or export option for gas, methane is often vented or flared. An alternative method is to reinject the gas back into the reservoir from which it was produced from. As well as cutting emissions the reinjected gas can increase oil production by increasing pressure within the reservoir.
Currently, approximately 145 billion cubic meters of gas are flared annually during oil & gas operations, and this results in roughly 2% of global methane emissions from Oil & Gas due to incomplete or inefficient combustion. Since the design of a flare depends on the volume and variations in gas flow, methods for improving combustion differ between low-volume and high-volume flares. Some measures involve making changes to flaring equipment, and others involve changing flaring practices. More efficient combustion can help cut these methane emissions from flares.
In most situations, methane can be viewed as a commodity with a value. Reducing emissions and losses of methane results in more gas to export or more gas to use for on-site power generation. When oil and gas companies invest in reducing methane emissions, they are not only delivering environmental benefits, they are often also able to capture financial benefits.
AIE has a dedicated service capability and expertise to help operators with methane emissions reductions. The AIE Methane services provides a structured approach to assess, identify, estimate, measure and take action to cut methane emissions.