HYDRAULIC FRACTURING ADVANCES
Centralized start-stop system
helps reduce fuel consumption,
emissions from idling engines in
hydraulic fracturing operations
Field testing in Permian last year showed
promising results, with significant decreases
in engine idling hours and emissions levels
BY STEPHEN WHITFIELD, ASSOCIATE EDITOR
As the industry continues to deploy inno-
vations like battery energy storage sys-
tems, dual-fuel and natural gas engines
to lower fuel consumption and mitigate
emissions during hydraulic fracturing
operations, another source of NO x , CO 2 and
particulate matter emissions is getting
more attention on the sustainability radar:
idling frac engines.
“These engines that we’re using on frac
sites were never designed to idle. They
were designed to run very efficiently at
50%, 60%, 70% power. The more load they
have on them, the better their lubrication
systems and radiation packages work. But
that means they’re consuming a lot of fuel,”
said Robert Fulks, VP of ESG Technology at
MGB Oilfield Solutions. “Frac engine emis-
sions have come way down because of the
technologies applied by manufacturers, but
they’re not as efficient in their fuel con-
sumption as you’d like them to be.”
Speaking at the 2023 SPE Hydraulic
Fracturing Technology Conference on 2
February in The Woodlands, Texas, Mr
Fulks outlined the development and field
testing of a new start-stop system designed
to mitigate fuel waste from idling engines.
Industrial diesel engines rely on per-
manently mounted batteries to drive elec-
tric starters. When a start-stop system
is added, it automatically shuts down
the engine when it’s not being used and
restarts it when it’s needed. This reduces
idling time and, therefore, fuel consump-
tion. The technology has been used in the
automotive industry for decades and was
adopted into the frac industry within the
past five to six years.
Last year, MGB launched its version of
the start-stop system with the addition
of a centralized power unit. This made
a significant difference as it meant that
each start-stop system would not have to
be manually activated on each individual
engine. By installing the start-stop system
inside the centralized starter unit, an
entire fleet of frac pumps can be started
from a single power source, or be shut
off when the pumps are not needed. This
reduces the time needed to stop/restart
a frac fleet to less than 10 minutes, com-
pared with around 45 minutes for a start-
stop system without a centralized starter
function, according to MGB.
“The big holdup with adopting start-
stop systems has been the amount of
time needed to restart an entire fleet,” Mr
Fulks said. “But now you can press a but-
ton and start-stop an entire frac fleet. You
don’t need to do the old way of having two
people go out to charge the hydraulic pump
on each tractor. This is a big deal if you
want to talk about efficiency.” Additionally,
the start-stop function can be performed
either remotely or autonomously, if used
with third-party automation software.
Different configurations
for system setup
MGB’s centralized hydraulic start-stop system can be configured in two settings –
a daisy chain setting where the main hydraulic supply line runs from the start-stop
unit to the first pump, and then subsequently to each pump on the pad; and a
manifold setting where hydraulic power flows from the start-stop unit to a series of
manifolds to the hydraulic pumps. Either configuration allows an entire fleet of frac
pumps to be started from a single power source.
34 MGB’s start-stop system can be laid out
in two configurations. One is the “daisy
chain,” where the main hydraulic supply
line runs from the hydraulic start-stop unit
to the first pump on a row of frac pumps.
Another hydraulic hose connects to this
first pump and runs to the adjacent pump.
This process repeats for all the pumps on
that row, and the same process repeats for
the other row. The other potential configu-
ration is a manifolded distribution layout,
where hydraulic power from the start-stop
unit runs to a manifold system with a set
M A R C H/A P R I L 2023 • D R I L L I N G C O N T R AC T O R
HYDRAULIC FRACTURING ADVANCES
number of outlets, which then provide
power to the connected frac pumps.
The layout of the individual frac pumps
determines the flow of the hydraulic fluid
to the frac pump starter. Either of the two
standard configurations of the frac pumps
can be deployed with the MGB system,
either with the daisy chain or the mani-
fold setup. The closed center configura-
tion means that, as hydraulic pressure is
applied to the starter circuit, the actual frac
pump starter motor will not engage until
a start signal is transmitted. When a sig-
nal is received, the solenoid valve on the
starter sends hydraulic fluid to the starter
to start the engine.
For the other starter configuration, the
open center, when the hydraulic fluid flows
to the starter circuit, the fluid bypasses
the solenoid valve and returns to a tank.
When enough fluid has passed to start the
engine, the solenoid valve activates and
sends the fluid to the starter motor. An
open-center setup requires additional ball
valves to control the flow of the hydraulic
fluid to each frac pump and eliminate flow
when it is not needed. In a closed-center
setup, no additional control valves are
required – the solenoid valves control the
flow to each frac pump.
The MGB start-stop system, and the cen-
tralized power unit, also reduce the need
for auxiliary equipment – like tractors, air
compressors, generators and diesel-pow-
ered light towers – that is typically needed
to power individual frac pumps. Mr Fulks
said this reduction in equipment provides
an added benefit to frac operators by reduc-
ing the number of potential points of failure
on a frac pad, lowering maintenance costs.
“The single central unit is basically pro-
viding all the power we need on location.
“Emissions monitoring system”
continued from page 33
suring CO 2 were run in the same location.
One was kept running, while the other
was intentionally stopped for a fixed dura-
tion. The interpolated data points from the
stopped sensor matched the CO 2 readings
from the other sensor, indicating the accu-
racy of the algorithms.
While most GHG levels recorded during
MONTHLY EMISSIONS
DURING FRAC IDLE TIME
UNITS BEFORE
CENTRAL START/STOP
AFTER CENTRAL
START/STOP N0 X per pad
grams 2,834,244
526,360 C0 2 per pad
Kgrams 695,520
129,168 Particulate Matter per pad
grams 26,372
4,898 Field testing of the centralized stop/start system, which took place over a three-
week period last year in the Permian Basin, showed significant drops in selected
greenhouse gas emissions and particulate matter. The centralized system had
helped to remove an average of 135.78 idle hours per pump, resulting in a savings
of 1,962.07 gallons of fuel per pump.
So, we don’t need all the generators, light
towers and compressors we have out there.
You won’t see any tractors on location. You
can daisy-chain everything to the unit.”
Field testing in the Permian
shows positive results
Last year, ConocoPhillips tested the start-
stop system on a frac pad in the Permian
Basin, using a real-time data analytic soft-
ware developed by Corva to measure frac
pump diesel usage, engine idle times and
emissions generated from the frac pad.
Use of the centralized start-stop system
took place during a three-week period in
mid-summer 2022. ConocoPhillips then
measured these totals against the average
idle time and fuel usage for the same pad
from a separate three-week period without
the centralized system.
The operator found that, with the cen-
tralized system, an average of 135.78 idle
hours were removed per pump over the
three-week period. This led to a savings of
1,962.07 gallons of fuel per pump, or a total
savings of 35,317.32 gals for the entire pad,
the pilot were below the threshold set by
the operator – 1 ppb of H 2 S, 12 ppb of NO 2
and 600 ppm of CO 2 – the sensor system
did detect a higher-than-expected level
of CO 2 levels in the closed cabin. This
confirmed the need for better ventilation,
Ms Narang said. Outside of the cabin, the
frac site did not see higher-than-expected
levels of GHG emissions.
Another more unexpected find during
the project was that there was a drop in
which used 18 active pumps. Assuming
an average diesel price of $3.80/gal, this
meant a fuel cost savings of $134,205.83.
When factoring in the reduction of
generator usage and light tower usage,
as well as the reduction in maintenance
costs enabled by the reduction in auxil-
iary equipment, the operator determined it
achieved a total cost savings of more than
a half-million dollars.
From an emissions standpoint, the MGB
system also recorded savings in NO x emis-
sions, CO 2 emissions and particulate mat-
ter (see graph above).
“You’re not going to eliminate all the
idle time because you’ve got to get the
engines up to speed and then bring them
back down – that takes time. But you can
eliminate a lot of the idle time, and you can
eliminate a lot of fuel consumption. The
field tests showed a dramatic difference,”
Mr Fulks said. DC
More information in SPE 212357, “Reductions
in Emissions and Fuel Cost with Start-Stop
System Technology for Diesel Frac Fleets.”
NO 2 emission levels during the daytime
hours. The team traced this to the fact
that, in the presence of sunlight, NO 2 is
converted to NO, and O 3 is released as a
byproduct; addressing this in the future
would likely require those two gases to be
measured, as well. DC
For more information, refer to SPE 212323,
“Towards a Net-Zero Future: Decarbonizing
Hydraulic Fracturing Operations.”
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