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.”
D R I L L I N G C O N T R AC T O R • M A R C H/A P R I L 2023
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