Percussion drilling

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Percussion drilling

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Percussion drilling

• Cable Tool Drilling
• Percussion drills have been used to drill
  thousands of feet, though they are generally used
  for wells from 30 to 250 feet deep.
• This drilling method has been used in China for
  over 3000 years.

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Hand powered percussion drill
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Method -The lifting and dropping of a heavy
(50kg) cutting tool will chip and excavate
material from a hole. - The tool can be fixed to
rigid drill-rods, or to a rope or cable. - With a
mechanical winch, depths of hundreds of metres
can be reached.
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Working of percussion drill

• The drill involves a heavy steel bit attached to
  a rope which is lifted, either by hand or by
  machine, and then dropped to cut the earth.
• As the bit chops the earth, water is added to the
  well hole so that the bit makes mud out of the
  earth it has cut.
• After the hole is filled with several feet of
  mud, the heavy bit is withdrawn and a tool called
  a bailer is attached to the rope and lowered into
  the hole.
• The bailer is a hollow tube with a door at the
  bottom.
• The door, called a flap valve, opens when it hits
  the mud to allow the mud to fill the bailer, and
  then closes to trap the mud inside the tube so
  that the mud can be lifted to the surface.
• The tube is emptied at the surface and the
  procedure is repeated until the hole is clear.

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Cont .

• The bit is then re-attached to the rope and the
  above process begins again.
• If the earth being drilled will not cave in, then
  the drilling continues until water is reached.
• But if the earth is made of loose material like
  sand, a large heavy steel pipe is driven into the
  hole to keep the walls from falling in.
• The large pipe is called casing and it holds the
  hole open until the drilling is done.
• It is removed after the permanent casing (usually
  smaller) is installed
• When the water level has been reached the
  drilling stops and the permanent casing, which is
  smaller than the well hole, is installed.
• hen the rest of the hole around the casing is
  filled and sealed.

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Materials

• Percussion gouges
• Electrical percussion hammer
• Connections
• Extraction systems

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Percussion gouges

• Used to take undisturbed samples from depth to
  about 10 meters.
• Higher drilling speed.
• The design enables easy emptying and cleaning.
• Depending on the soil type, drilling depth and
  desired quantity of sample one of various gouge
  types is chosen.
• Available in various diameters 40, 50, 60, 75 and
  100 mm and with a length of 50, 100 and 200 cm.
• All percussion gouges have a hardened steel
  cutting head

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Percussion gouges in various diameters
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Electrical percussion hammer,

• Light model
• - Beating power of 31.7 Joule at 1200 beats per
  minute, a net weight of 17 kg and an overall
  length of 613 mm.
• Heavy model
• - Beating power of 55.3 Joule at 1000 beats per
  minute, a net weight of 29.1 kg and an overall
  length of 825 mm.

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• RD32-connection
• Extension rods and percussion gouges are screwed
  together using a coupling sleeve.
• Takes very little time to attach and take off.
• The RD32-rods connect together by means of a
  coupling sleeve
• Wedge-connection
• The gouges and the extension rods are connected
  using so called wedge connections
• Easy and quick coupling and un-coupling is
  possible.

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RD32-connection
Wedge connection
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Pulling devices (rod pullers)
Rod puller extension for the first gouge
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Extraction system

• Pulling device (Rod pullers)
• Rod puller extension
• Hydraulic extrator
• Pulling force of 80 kN, is supplied with
  extracting cylinder (diameter 65 mm) and a
  hydraulic aggregate with electric hydraulic
  extractor tube set.

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Hydraulic extraction system
Hydraulic extractor
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Percussion drilling applied,

• If drilling has to be executed in hard soils,
  possible containing layers of rubble and/or
  stones usually percussion drilling is applied.
• Percussion drilling for instance is applied for
  research on soil pollution, grain size
  distribution, general soil classification,
  profile descriptions, etc.

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Advantages of percussion drilling Simple to
operate and maintain. Suitable for a wide
variety of rocks. Operation is possible above
and below the water-table. It is possible to
drill to considerable depths.
Disadvantages of percussion drilling Slow,
compared with other methods. Equipment can be
heavy. Problems can occur with unstable rock
formations. Water is needed for dry holes to
help remove cuttings.
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References
http//www.albertasource.ca/petroleum/technology/
innovations_profiles_percussion_drilling.html
www.wellspringafrica.org/drildesc.htm www.eko
technika.cz/pdf/P1-21e.pdf www.lboro.ac.uk/well/r
esources/technical-briefs/43-simple-drilling-metho
ds.pdf
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Questions ??