American Oil and Gas Reporter - August 2015 - 78

SpecialReport: Hydraulic Fracturing Technology
system employs powered swivel and orientation tools that, when deployed with
a gun brake, enable long strings of guns
to be oriented accurately."
Coiled tubing frequently is deployed
to get guns to the right depth, but because
traditional wireline deployment generally
is more time and cost efficient, most operators prefer to use wireline. "To get
wireline tools on bottom, the operator
needs to move them along the horizontal
lateral where gravity is an enemy rather
than an aid. As a result, the guns must be
pumped down, sometimes with help from
a tractor," he notes.
"Once the tools are on bottom, the
operator has to rotate an extremely long
set of guns-often in excess of 1,000 feet
in length-so they can fire in the optimal
stress direction and avoid shooting through
external control lines. Friction and gravity
combine in this situation, so the swivel
that turns the guns needs to be powerful,"
Keenan says.
"With the BDS, the cable head tension
tool monitors compression and tension
loads on the cable to help optimize running
speeds while running in and pulling out
of the hole, particularly during pumpdown operations," Keenan continues, noting that this gives the operator better
control of the line speed.
"We have had customers tell us that
using this tool is like removing blinders,"
he comments. "They know how well the

pump-down job is working at getting the
guns to bottom, so they can avoid applying
too little pump pressure, which wastes
rig time, or too much, which might blow
the guns and tools off the cable."
Keenan describes the integrated system
as addressable. "Our customers, the wireline companies, can communicate with
the Guardian tools, so they can control
exactly what is happening to the string
and the guns," he says.
The system has been designed from
the ground up to be easy and safe to deploy, Keenan reports. "Because the system
is integrated, all the information from
the tools is controlled through a single
multipurpose panel located in the wireline
truck," he notes. "Instead of having panels
for each tool, the wireline engineer only
needs to look at one panel, which reduces
the chance for mistakes."
"Minimizing the opportunity for human
error has been a major goal throughout
the system's design," says John McGrath,
Guardian's director of sales and marketing.
"We have achieved that goal partly through
automation. For example, the Select Fire
Switch (SFS), which controls when the
guns fire, automatically identifies the
detonator that is in each gun in order to
activate at the appropriate intensity and
current.
"Because the SFS is part of the system,
Guardian is able to implement additional
safety and reliability protections," McGrath

Guardian Global Technologies
has introduced an integrated
system for placing, firing and removing perforating guns that includes everything from an
addressable release tool to a
gamma ray and collar locator.
The company says the system
increases perforating operations' safety and efficiency by
reducing the chance of mistakes.

78 THE AMERICAN OIL & GAS REPORTER

continues. "The system will not allow
the switches to fire until the gun has
reached its designated depth, which prevents off-depth perforating incidents,
which in turn saves lives," he says.
To prevent surface detonation, the
switch will not detonate until the operator
arms the gun by breaking off a mechanical
tab. "We went with a tab-based system
to prevent confusion," McGrath says.
"After arming the guns, the engineer can
count the number of tabs in his pocket
and verify that it matches the number of
guns. This mitigates the risk that one is
unarmed in the event he did not set a
rotary switch all the way or missed a
depth switch. Moreover, it will be easy
to spot any unarmed guns."
To provide extra safety in specific applications, the SFS can include a sensor
that prevents the gun from firing until
the temperature reaches 170 degrees
Fahrenheit. "With the sensor, the gun
cannot fire at surface, no matter what,"
McGrath states. "This system introduces
new levels of safety assurance to eliminate
mistakes and prevent accidents while
making sure the guns are delivered accurately and efficiently."
Perforating Charges
Shaped charges play a key role in effective completions, says Nathan G. Clark,
the senior vice president of perforating
and technology for GEODynamics. "In
most applications, our goal is to design
shaped charges that create a large, clear
tunnel. If we can do that, we will maximize
production," he comments.
Creating effective tunnels is far more
difficult in practice than in theory, Clark
says. He points out that many operators
evaluate charges based on American Petroleum Institute tests, which are done
on unstressed cement targets with a minimum compressive strength of 5,000 psi.
"Concrete is a much easier target for
shaped charges than competent rock that
has effective stress on it," Clark emphasizes. "In fact, shooting into competent
rock usually cuts the penetration in half.
A shaped charge that delivers almost 70
inches of penetration in a cement test
might only go 25 inches downhole."
To ensure its shaped charges will be
effective, Clark says GEODynamics tests
its charges by stressing cores that resemble
the rock the client expects to perforate.
"By simulating downhole conditions, we
are able to look at the effects of shooting
in a balanced, underbalanced, or over-

American Oil and Gas Reporter - August 2015

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