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Oilfield Technology
August
2015
Workovers are all the more essential as expanded regulatory
criteria mean existing assets may no longer meet well integrity
requirements. New technologies are emerging and existing tools
are advancing to meet these needs of the industry.
Well designs are improving to incorporate pre‑planning
for future well intervention needs, but many older assets,
even absent such provisions, can offer an excellent return on
investment if economical intervention methods are available.
These operations can often be extremely challenging; however,
as there is typically a high level of uncertainty in regards to
the condition of the casing, cement, and other downhole
components.
As wells age, failures can occur involving the complex
hardware installed to control production or injection flows.
Quite often, a component leak can cause sustained casing
pressure in the annulus. The economics of using a rig to perform
interventions on an older well can be difficult to justify, so
wireline is often used for such interventions. Reliable wireline
setting options are available for use in deploying an inflatable
packer to locate and isolate a leak. For highly deviated wells,
the system can also be deployed with a wireline tractor.
Riglesssettingmethodsareadvancing
TAM International’s slickline setting tool SlikPak has been
available for several years, enabling innovative intervention
approaches. Since then, the ongoing demands of deepwater
development have driven the need for technology that can
perform in deeper, hotter well conditions. TAM is preparing for
the commercial release of its next‑generation setting tool, which
is currently undergoing field trials. This new technology will
significantly increase the performance envelope and capabilities
of inflatable packers. Bridge plugs can also be set with the new
setting tool.
The inflatable setting tool system consists of a
self‑contained battery power unit and a downhole pump, which
inflates the bridge plug or packer with wellbore fluid or with
clean fluid carried in onboard reservoirs from the surface. The
standard packer or plug sizes available for routine deepwater
interventions using this tool range from 2
⅛
‑ 3 ¾ in. OD, with
larger sizes available when required. The new system is rated for
bottom hole pressures up to 15 000 psi and 300˚F.
An onboard downhole computer controls the downhole
setting sequence to ensure proper setting pressures are
achieved and to prevent premature setting. Once the computer
has determined that the packer can be set, it starts a motor that
controls a high‑pressure pump to inflate the packer. Downhole
data is captured, downloaded, and analysed to verify all
systems performed properly downhole.
One of the limiting factors for an inflatable packer is the
amount of setting pressure possible inside the element. Higher
inflation pressures mean better holding forces and ultimately
higher differential pressure ratings. When setting inflatables on
pipe, this setting pressure is limited only by the rating of the
packer element. However, when setting inflatables on slickline
or wireline, the limits on setting pressure are determined
by the capabilities of the downhole setting tool, such as the
capacity for pump pressure output or the ability to increase
pressure by pulling tension on the line. The pressure limits of
existing slickline setting tools available on the market have
been acceptable for a wide variety of applications. But the
new technology setting tool will significantly increase the
inflation pressure available to inflatable elements downhole in
through‑tubing applications.
Element capabilities increasingtomeetmarket
needs
In conjunction with the new setting tool, inflatable element
technology is also evolving to provide a greater working
Figure 2.
Illustration of Scab Liner Installation.
Figure 1.
Record of setting sequence.
