LOW-CARBON DRILLING SOLUTIONS
Left: NOV’s Eco Booster system, launched last year, contains an accumulator skid (pictured) that stores and distributes power
to the hydraulic pumps powering a rig’s ring line system, reducing power usage during periods of peak demand. Right: NOV’s
iNOVaTHERM, a portable unit for treating and disposing of drilling waste on the rig, has been used on four drilling campaigns
in the North Sea since its commercial launch in January 2021.
system to generator sets. To deal with the potential hydraulic
demands at peak usage, more pumps are running than what is
really needed for a large percentage of the time. Pumps running
idle for 24 hours a day consume a large amount of electricity and
fuel, continuously emitting CO2 and NOx. However, the pumps
need to be able to handle sudden increases in flow requirements
when the hydraulic pump is activated. Hydraulic equipment
already in operation will also be affected by this pressure drop.
To help operators use their hydraulic pumps more efficiently,
thereby reducing power usage and emissions, NOV launched its
Eco Booster system last year. Eco Booster is a hydraulic energy
storage system that optimizes hydraulic ring line performance
by storing hydraulic power when demand is low and releasing
hydraulic power when demand is high. When additional flow
is required, the technology transfers hydraulic energy from the
accumulators, limiting the need for additional hydraulic pumps
to start up.
“This system basically eliminates that pressure drop. Instead
of having the pumps increase their RPM to boost the pressure
in the system, Eco Booster provides that short peak of hydraulic
power. Instead of having all of your pumps running all of the
time, you can reduce the number of motors and pumps that
are running. That’s where the power usage savings come from.
That’s where the emissions savings come from,” Mr Verhoef
said. The technology is made up of an accumulator skid with four
nitrogen pre-charged accumulators, a booster skid and an auto-
mated control system. The accumulator is charged by a pressure
booster when the ring line flow consumption is low.
When charged, the accumulator matches the flow require-
ments and demands of the equipment, even when those require-
ments and demands exceed the ring line pump’s capacity. The
accumulator also stores power during periods of light loading
on the hydraulic equipment – a process known as load leveling
– leading to more optimal use of the hydraulic pumps. The Eco
Booster also dampens the variations caused by sudden power
demands, providing instant flow and pressure to the ring line.
NOV estimated the savings it could generate from the Eco
Booster based on historical power usage data. A rig typically runs
six hydraulic pumps 24 hours a day , with each pump consuming
55 kW of power each day. Each pump burns an average of 0.2875
liter/kW used, and NOV calculated 3.23 kg of CO2 and 4.2 g of NOx
emitted for every liter of fuel burned on the rig.
With the Eco Booster system installed, a rig can potentially
run on four generators 65% of the time it is in operation. Over the
course of an entire year, this would mean annual fuel savings of
180,072 liters. Emissions-wise, that annual fuel savings would
lead to 581 tons of CO2 saved and 756 kg of NOx savings per year.
Some countries already impose taxes on CO2 and NOx emis-
sions, resulting in an even higher operational cost to the rigs oper-
ating in those areas. Even if the system is used in an area without
emissions taxes, Mr Verhoef noted that operators can make up
the cost of installation in a few years. “If you’re saving tens of
thousands a year in fuel costs, this system becomes a relatively
small investment for the customer with a pretty good return on
investment. The more pumps you can put offline, the better the
savings, and the more stable the hydraulic system is, the better
you are with emissions.”
Since its commercial launch in 2021, the Eco Booster system
has been installed on one rig for a major operator in the North Sea.
Mr Verhoef said NOV has commitments to install four additional
units for separate operators later this year. DC
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