American Oil and Gas Reporter - November 2023 - 69

SpecialReport: Emissions Monitoring
makes the most sense depends in part on
a location's accessibility, how frequently
regulators require information, the value
of the lost methane and whether the facility
is subject to emissions taxes, Tang outlines.
He says instrumenting facilities can be
quite affordable, with some only requiring
a few sensors or an investment of a few
thousand dollars.
The information continuous monitoring
provides occasionally unlocks cost savings
in other areas, he adds, such as optimized
electrical automation, and health and safety
programs. " For example, it is common to
see compressor buildings classified as Class
I, Division I based on assumptions about
the explosive gasses in the area, " Tang
says. " If the monitors show that the building
qualifies as Class I, Division II, the owner
can use less expensive systems to monitor
machine health. In general, Class I, Division
II equipment costs about 40% less. "
Holistic View
Although he describes continuous monitoring
as an important component of emissions
management, Tang stresses that
progress will require a diverse tool set
that includes everything from handheld
OGI cameras to drones, helicopters, planes
and satellites. OGI cameras and drones
can provide detailed information on a well
pad or facility, while long-range drones,
planes and satellites cover multiple facilities
in asset-dense regions or geographically
dispersed assets such as pipelines.
" There is no silver bullet, " Tang says.
" Every tool has pros and cons in terms
of its economics, how many sites it can
survey and the level of detail it can
provide. It can be challenging to derive
actionable insights from data that varies
in resolution, acquisition time, GNSS positioning
and detection thresholds. But
with software capable of integrating the
data, we can use these tools in harmony
to significantly reduce the uncertainties
associated with quantifying emissions
and prioritizing investments. "
Ultimately, Tang envisions the industry
linking emissions data with other operational
information to improve operators' understanding
of why emissions occur and how
to stop them. " Sometimes the best bang
for every buck will come not from emissions-specific
solutions but from investing
in artificial lift technologies or more effective
chemicals that extract hydrocarbons from
the subsurface more efficiently, " he says.
Providing reliable and affordable energy
remains the industry's primary goal, he
assures, even if the strategy for how to
do so incorporates more considerations.
" The costs companies consider have expanded
beyond dollars and cents to include
tons of carbon dioxide emissions, " Tang
says. " As the industry collects more emissions
data and refines the tools to analyze
that data, we will continue to get better
at mitigating emissions. "
Up-Close Monitoring
Most continuous monitoring systems
do not qualify as intrinsically safe and
need to be placed at the edge of a well
pad or facility, observes Seth Long, chief
executive officer of Shepherd Safety Systems
LLC. " This puts the monitor 100200
feet away from the source of emissions
and means it can only pick up emissions
that happen to drift across the sensor, " he
says. " In fields with several facilities
close together, it can be hard to tell where
the emissions originate.
" The approach we have taken is to develop
intrinsically safe devices that are
certified for Class I, Division I areas, which
means they can be put right next to emission
sources. For example, we often install sensors
by storage tanks' thief hatches, " Long
contrasts. " The sensors are labeled based
on their location, so if one picks up a leak,
it's much easier to pinpoint the source. "
When they detect unusual emissions,
Shepherd's sensor arrays can send emails,
messages and alerts to the right people to
speed response times, Long says. He adds
that the sensors tie into production facilities'
existing SCADA systems. " This helps
companies compare emissions data to operational
data such as tank levels and
pressure readings, which sometimes reveals
why the emissions are occurring and helps
companies prevent them, " he suggests.
Those gradual improvements already
are taking place, Long conveys. " We have
data on hydrogen sulfide and other safety
concerns going back to when we started
in 2007, " he reports. " Over time, the
number of gas events has fallen. "
To show how operational data complements
emissions monitoring, Long cites
a customer whose sensors occasionally
detected emissions from the pressure relief
valves on its tank batteries. " By looking
at vapor recovery unit pressures, the
operator quickly realized the relief valves
had opened because the VRU shut down, "
Long recounts. " Since then, the customer
has streamlined VRU operations to increase
uptime. Today, its methane intensity is
among the lowest in the Permian Basin. "
Several operators are replacing traditional
thief hatches with newer designs,
Long adds. " Most of the emissions from
production facilities come from thief
hatches that fail to seal properly or stay
open after activating, " he explains. " Replacing
legacy hatches is one of the lowest-hanging
fruits for reducing emissions. "
Most production facilities only need
four-five sensors to monitor emissions
This central production facility in South Texas is using sensors from Shepherd Safety
Systems to watch for emissions. Because they are certified as intrinsically safe, the
sensors can be placed near potential emission sources in Class I, Division I environments.
According to Shepherd, such proximity makes it easy to locate any issues they detect.
NOVEMBER 2023 69

American Oil and Gas Reporter - November 2023

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