American Oil and Gas Reporter - September 2016 - 86

SpecialReport: Tubulars Technology

Tools Help Coiled Tubing Go Further
By Colter Cookson
Whether it is used to drill wells, remove
fracturing plugs, or clean out scale and
paraffin, coiled tubing has an advantage
that has become particularly relevant: It
often is less expensive than traditional
methods.
To deliver cost savings to as many oil
and gas producers as possible, coiled
tubing manufacturers, tool designers, and
service companies report they are applying
every technique at their disposal to make
CT solutions reliable and effective in a
wider variety of wells.
With horizontals getting longer and
longer in many plays, CT companies
have been challenged to figure out how
to get coiled tubing farther into a long
lateral section without using such large
and heavy strings that the coil becomes
impractical to transport. Bright minds
from across the industry say they are
coming up with answers in the form of
more reliable and cost-effective vibration
tools to reduce friction acting on the
tubing, and better string designs.
Others report refining downhole CT
tractors to give them the capacity to carry
heavier strings to the toe of ultralong laterals while maintaining the flexibility to

get through tight restrictions and borehole
undulations.
Still others say new tools are enabling
CT units to drill through plugs, debris
and scale in record time. And today's
monitoring hardware and fatigue models
are reducing costs by allowing service
companies to use a string of coiled tubing
longer without putting the job or the
people on site at risk.
Clean-Out Tools
Both tool manufacturers and service
companies express excitement about coiled
tubing's long-term potential and say they
look forward to allocating more funds to
research and development as oil prices
and activity recover. In the short term,
many say they are concentrating on helping
operators maximize production from existing assets.
"Because drilling has been down for
the past two years, operators have increasingly focused on preserving production rates from existing wells," observes
Jeff Chestnut, chief operating officer of
Coiled Tubing Technology Inc. "As a result, there is a lot of effort going into developing tools used for clean-out and
restimulation.
"One tool that has been particularly

Downhole tools such as this jar are
becoming tougher and more effective as tool suppliers refine their
designs. However, Coiled Tubing
Technology Inc. emphasizes that
carefully inspecting and redressing tools after each job remains
vital to minimizing downtime.

86 THE AMERICAN OIL & GAS REPORTER

popular is jet nozzles," he says. "In
addition to the traditional high-velocity
nozzles, there are new surging nozzles
that generate a pulsed pressure. In other
words, they go from a high pressure and
volume to a low pressure and volume."
As with any clean-out tool, Chestnut
says these new nozzles excel in certain
applications. "The traditional high-velocity
nozzles work extremely well with paraffin
and asphalt plugs," he says. "The surging
tools are finding success in more recently
drilled wells that have sand buildup. We
have not tested the surging nozzles on
every type of scale, but they may be
more effective at distributing the acid in
acidizing jobs than traditional designs."
In many applications, Chestnut recommends specifying a motor with a metal-to-metal seal rather than an elastomer
seal. "In a deeper well, the operator often
wants to use nitrogen, a foam, or acid,"
he observes. "A metal-to-metal seal can
handle all three of those fluid systems
and works well whether it is in a shallow,
cold well, or a deep, 400-degree well."
Chestnut encourages operators to review the bottom-hole assembly that the
through-tubing service provider plans to
use. "It is vital that the tools be compatible
with one another and with the rest of the
BHA," he emphasizes. "For instance,
many BHAs include an oscillating device
to reduce friction so the coiled tubing
can make it to the end of a long lateral. If
that device is put right behind the motor,
it can destroy the motor's thrust bearing.
"Another common mistake is using a
hammer with a coil connector that cannot
handle the amount of force being applied
up and down the CT string," he continues.
"As a result, the connector can disconnect."
To prevent such events, Chestnut advises operators to look for partners who
have great track records, careful engineers,
and meticulous suppliers. "Tool suppliers
need to be picky in the shop," he insists.
"When a rental tool comes in from a job,
they need to take it apart, do rigorous
nondestructive testing and visual inspections, replace damaged parts, reassemble
the tool with care, and test the final
product before it goes back out."
Pushing Length Limits
By combining extensive prejob planning with reliable equipment, Cudd Energy

American Oil and Gas Reporter - September 2016

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