Methane emissions from upstream oil and gas by scenario, 2020
---- Reducing methane releases to the atmosphere in upstream oil and gas operations ---
Energy-related methane emissions stem from the production, transportation, distribution
and use of all fossi...
l fuels and from biomass combustion. We estimate that such emissions
currently amount to 125 Mt CH4 per year. Using the standard 100-years GWP of 25 from
the Intergovernmental Panel on Climate Change (IPCC), this amounts to 3.1 Gt CO2-eq. It
should be stressed however that there is a shortage of hard, measured, data on methane
emissions estimates rely primarily on multiplying emissions factors for various activities
by activity levels the emissions factors themselves can be traced to studies made by the
Gas Research Institute and US EPA in the United States (US EPA, 2013).
In the oil and gas industry, methane emissions occur across the entire value chain.15
Transmission and distribution of natural gas releases considerable amounts of methane
into the atmosphere due to leakage or venting (which may be voluntary or involuntary),
particularly in countries with a large and ageing distribution network, such as Russia and
the United States. Additional methane emissions occur during incomplete combustion,
both in end-use and in flaring. The extent of emissions in transmission, distribution and
end-use is poorly known, as many of these emissions result from unintended leaks in ageing
infrastructure. Addressing such leakage is a challenging and potentially costly task, beyond
the short-term focus considered here. The larger potential for reducing methane emissions
from oil and gas in the short term lies in optimising operational practices upstream, where
the sources of emissions are relatively well-known. Technologies to reduce them are
available (in large part through the work of the US EPA Gas Star Program) and the necessary
action can be implemented through the existing sophisticated industry, dominated by large
companies with strong technical skills and budgets. We estimate that the global oil and gas
upstream industry released 45 Mt of CH4 emissions (1 115 Mt CO2-eq) to the atmosphere
in 2010 (Spotlight).
Both venting and flaring give rise to methane emissions during oil and gas field operations.
venting (as defined here) includes both the intentional release of methane to the
atmosphere (as part of normal operations) and "fugitive emissions", which are unintended
the results of leaks, incidents, or ageing or poorly maintained equipment. Some
emissions from venting can be reduced at comparatively low cost by applying operational
best practices, such as increased inspection and repairs, minimising emissions during
completion operations and workovers, and reducing the frequency of start-ups and
blow-downs. Equipment can also be converted, or designed, to reduce emissions: low-cost
options include modifying dehydrators and convering gas-driven pumps and gas pneumatic
device controls to mechanical controls. Additional but more capital-intensive potential
lies, for example, in replacing leaking compressors with new ones and installing vapour
recovery units on tanks. Production of unconventional gas has been particularly criticised
because of the large amount of methane that can be released to the atmosphere during
the flowback phase after hydraulic fracturing. Controlling such emissions is part of the IEA
"Golden Rules" for unconventional gas development, and such rules are being adopted
in a growing number of countries, for example in the US EPA's New Source Performance
Standards for the oil and gas industry in the United States (IEA, 2012c).
Gas that becomes available in relatively large quantities as a by-product of oil production
(associated gas) often has no commercially viable outlet. It will not normally be vented,
for safety reasons, but will be flared. Gas flaring converts methane into CO2, i.e. still a
greenhouse gas, but with lower Global warming Potential. Reducing flaring has been a
long-standing goal of the international community " it would substantially reduce both CO2
and methane emissions " but the large investment required cannot materialise quickly.
On the other hand, combustion is not always fully complete, which means that unburned
methane is inadvertently released to the atmosphere from an otherwise controlled process,
the amount varying with the design of the flaring equipment, and other parameters, such
as wind speed (US EPA, 2012b). To reduce flaring on a large scale, infrastructure and
equipment, such as compressors and pipelines, need to be built to bring the gas to markets
or to enable it to be used for local power generation a comparatively capital-intensive
process. Less capital-intensive options, such as the optimisation of flaring equipment or gas
re-injection, need to be promoted in the short term.
All the technologies to pursue short-term optimisation from upstream operations in
order to reduce methane emissions from venting and flaring are readily available, which
means that the pace of reduction can be significant if the right policies and enforcement
procedures are adopted (Figure 2.10). In the 4-for-2 °C Scenario, such short-term policies,
including reducing venting and improving flaring effciency, reduce methane emissions from
oil field operations by about 300 Mt CO2-eq. in 2020 (or 40% of oil-supply related methane
emissions), relative to the New Policies Scenario, in which no additional regulation to
are often unavailable. Another essential ingredient for success is raising awareness.
Operators themselves, in particular in dispersed operations, are often unaware of the
extent of their emissions and lack appropriate detection and measurement equipment.
In relation to the reduction of venting, at least, this points to an initial focus on large,
concentrated operations. A number of related efforts are currently underway, including the
Global Methane Initiative and the US Natural Gas STAR Program. Supplementary options
include extending carbon tax or trading schemes to methane, and imposing mandatory
requirements to implement appropriate methane emissions control technologies and
adopt best practices.
address venting and flaring is assumed beyond that in place today, such as those targeting
"green" completion equipment in the US EPA's New Source Performance Standards for the
oil and gas industry. For gas flared operations, the decrease is 280 Mt CO2-eq (or about 55% of
gas supply-related methane releases). The largest reductions are in Russia, the Middle East,
Africa and the United States. They are achieved through a combination of rapid and broadbased
implementation of low-cost and technological best operational practices, e.g. fewer
start-ups-shutdowns, more frequent inspections, installation of electronic flare igniton,
replacement of pneumatic controls by mechanical ones and upgraded dehydrators.
These measures would account for about half of the reduction in emissions in 2020. The
remainder would be accounted for by the first results from reduction endeavours that
are more complex, take more time to implement and require larger investments. This
category includes modifications like the installation of pressurised storage tanks with
vapour recovery units, replacing compressors by ones with higher emissions standards
and capturing emissions from individual wells. The impact of these measures would be
even larger beyond 2020, as methane emissions from the upstream are likely to continue
to increase in line with increasing oil and gas production.
Regulations exist in many countries to reduce venting and flaring, for example, in Russia,
Ukraine, Argentina and Colombia. But there is often a lack of means of enforcement,
particularly for venting. while the extent to which gas is flared is visible, vents are invisible
and effective enforcement demands installation of specific equipment (for example,
infrared cameras) and carrying out specific measurements.