Cutting Bed Impeller

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Cutting Bed Impeller (CBI)
The Pilot Drilling Control LTD Cutting Bed
Impeller (CBI) is a down hole drill string tool
intended for use in deviated wells where
excessive buildup of cuttings causes drilling
problems.   The CBI is an integral drill string
component consisting of a short mandrel with no
moving parts, shaped in such a way as to
stimulate any cuttings which have a tendency to
settle out of the mud in the high angled sections
of the well bore. The high angled sections could
be inside the casing or in open hole the tool is
adaptable to suit all borehole environments and
only a small number of tools are required to
successfully perform the task of maintaining a
clean borehole free of cutting debris and
eliminate the risk of stuck pipe and casing.
Pilot Drilling Control Ltd Nouvotech
House Harbour Rd. Ind. Est. Lowestoft,
Suffolk NR32 3LZ, UK Tel [phone]
588422 Fax [phone] www.pdc-uk.com
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Cutting Bed Impeller
Description   The Pilot Drilling Control Cutting
Bed Impeller (CBI) is a down hole drill string
tool intended for use in deviated wells where
excessive buildup of cuttings causes drilling
problems. The CBI is an integral drill string
component consisting of a short mandrel with no
moving parts, shaped in such a way as to
stimulate any cuttings which have a tendency to
settle out of the mud in the high angled sections
of the well bore. The high angled sections could
be inside the casing or in open hole the tool is
adaptable to suit several environments. This tool
has a proven track record throughout the world.

• Features
• One piece mandrel with mechanical properties
  which exceed the drill pipe in which it is
  placed.
• Dimensions which allow the use of up to two
  tools within a standard drilling stand in most
  drilling derricks.
• Hydraulic and mechanical dual acting mechanisms
  to remove cuttings beds.
• Tool can be dressed with different coatings
  according to the severity of the downhole
  conditions.

Incut zone designed to encourage loosening of
cuttings beds and allow for flexibility in the
mandrel.
Chevron shaped blades to ensure effective cutting
agitation in both directions.

• Benefits
• Reduces torque and drag on the string while in
  drilling mode.
• Reduces wear on the drill pipe and rotating
  equipment.
• Ensures cleaner and more stable hole conditions.
• Reduces drilling costs.
• Only a small number of tools are required for
  effective hole cleaning.
• Acts as a vibration damper in the string.

Mandrel strength matches maximum strength of
drill pipe tool joint.
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• Application
• Inside Casing In Open Hole
•  
• The CBI tool is designed so that the coating over
  the top of the blades is suitable for both
  applications in which it will be used. When
  running the tools primarily inside casing the
  coating has a low friction property to reduce
  casing wear. But the coating is also durable for
  all open hole applications.
•  
• Shown below is a typical case where cuttings
  have fallen out of the mud and have come to rest
  just below the build section. This build up of
  cuttings beds can have serious effects on the
  drilling operation. The most effective spacing of
  the CBI tools is normally between 300 and 500
  throughout the tangent section, which will ensure
  that the cuttings are re-agitated and
  re-introduced to the mud flow.

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Computer Aided Fluid Dynamics Simulations
(CFD) The latest Computational Fluid Dynamics
(CFD) modeling software is used to simulate the
flow direction and magnitude around a CBI surface
when used in a clean hole, and in a hole with
cuttings laying on the lower side. (Fig 1)
simulates the hole with cuttings on the lower
side of the hole. (Fig 2) simulates the clean
hole condition, showing the hole will then be
kept clean due the fluid dynamics around the
Chevron blades, higher velocity is shown in the
red, and the lower velocity in the blue, fluid
direction shown by the vector lines as the fluid
passes over the surface of the CBI. When the CBI
tool is used, the Chevron shaped blades scoop the
cuttings from the lower side of the hole. The
side of the tool that is in contact with the
cutting beds has a lower the flow velocity. The
Chevron shaped blades agitate and scoops the
cuttings from the lower side of the hole.
Cuttings are captured between the blades then
drifted around to the high side of the hole where
the higher turbulent velocity fluid flushes the
cuttings back to the annulus.   Shown also in the
figures overleaf are the flow around the blades
have higher velocity magnitude, this is due to
the larger cross sectional area across that
section. This higher magnitude of fluid velocity
helps flush clean between the Chevrons when they
are in the upper side of the hole and thus moves
the agitated particles back into the solution in
the annulus, in other words, the flow is more
turbulent there.   The two figures also show
that the flow around the blades changes direction
according to the shape of the blade, this helps
generate the turbulent conditions and thus
enhances the cleaning action around the tool,
and if there are cuttings in the Chevron pockets
the high velocity turbulent fluid will clean more
effectively.


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Fig 1
Fig 2
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Technical Specifications
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