American Oil and Gas Reporter - August 2015 - 87

SpecialReport: Hydraulic Fracturing Technology

Power System Simplifies Rig Moves
By Colter Cookson

Drilling contractors and rig component
suppliers have a long history of looking
for ways to operate more efficiently. Today, that often means reducing the time
required to move from pad to pad and
"walk" or slide from wellhead to wellhead
on a pad. A new power distribution and
control system achieves these goals by
eliminating the maze of power and communication cables normally required on
walking rigs.
On a traditional walking rig, power
moves from the power house to the rig on
20-40 600-volt cables, notes Norman Myers,
president of Integrated Drive Systems LLC.
The cables hang in tightly-packed loops
called festoons that expand "like an accordion" as the rig walks away from the
power house. Each cable requires two or
three connections that must be unplugged
and plugged back in every time the rig
moves from pad to pad, he says. If the rig
needs to walk even longer distances, more
connections and hardware may be required.
Integrated Drive Systems' new power
distribution and control system replaces
the power and control cables, the associated
connections, and the festoon with a single
cable that is attached to a reel on the rig's
substructure, according to Myers. A transformer by the power house generators steps
the voltage up to 4,160 volts, enabling the
system to transfer power to the rig on much
smaller cable. Then a second transformer
steps the power back down to the 600 volts
expected by the drilling equipment.
"With this approach, we only need
three connections: one at the main control
house, at the transformer that increases
the voltage to 4,160; one at the cable reel
that travels with the rig; and one at the
local equipment room on the drilling
floor," states Myers.
Brett Schellenberg, a marketing executive at Orion Drilling, which has deployed

the system on two new rigs designed for
multiwell horizontal pad drilling in the
Marcellus and Utica shale plays, says the
system's small cable count reduces copper-related costs and accelerates rig moves.
"In our first move with the system, we
saved eight hours," he reports.

Reliability
"We are excited about the system not
only because it reduces move times, but
also because it increases reliability,"
Schellenberg continues. "Water, dirt and
other materials can get inside plugs when
they are disconnected and dropped, so
plugs are one of the biggest failure points
during rig moves. The new system's
plugs close themselves off from outside
materials, and there are only a few of
them, so they are easier for the rig crews
to take care of."
Rigs that use the system house the
variable frequency drives (VFDs) for the
top drive and the draw works, as well as
the motor control center, on the rig floor
rather than in the power house. Schellenberg points out that this puts the driller
close to the motor control center. "The
driller often is one of the most experienced
guys on the rig, and he only needs to
walk through one door to help the motor
man troubleshoot any problems with the

VFDs," he says.
Putting the VFDs on the rig floor has
one other benefit, Myers points out. "Instead of having 150 feet of control wire
between the VFD and the equipment,
there is only 20 feet. The control wiring
is no longer copper, it is fiber optic,
which eliminates electric noise issues
that historically have been a problem for
walking rigs."
The driller can control the mud pumps
and generators at the power house through
a fiber optic communication cable that is
on a separate reel, Myers says.
The system improves safety by eliminating tripping hazards presented by the
maze of cables and the risk of muscle
strain associated with moving them, according to Schellenberg.
Myers adds that it reduces the chance
a poorly-connected, and therefore poorly
grounded, cable will cause electricityrelated injuries.
Although the system transfers power
to the rig at 4,160 volts, Myers says it
operates similarly to the 600-volt systems
traditionally used on land rigs. "All the
switchgear is at 600 volts, so it will take
up the same space on the rig. Also, any
troubleshooting will be at 600 volts and
below, which is what rig personnel are
used to," he concludes.
❒

Coming In September

Tubulars Technology special reports, surveying long-term supply
and demand fundamentals in the
OCTG market and examining advanced tubular connections and composites for long-lateral horizontal
wells.

In a new power distribution and control system, two single-cable reels on the rig
substructure replace the festoons traditionally used to hold the power and communication
cables that link the rig to the power house. Drilling contractors say the system will reduce
move times, increase reliability, and simplify walks to off-center wellheads.

AUGUST 2015 87

American Oil and Gas Reporter - August 2015

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