D M T 2006

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D M T 2006
Washington D.C. 2nd-4th April 2006
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WIRE-LINE MEDUSA
Electronic DMT for great depth
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Drilling and coring
For shallow continuous coring bore-holes the
commoniest method is using the simple tube core
barrel As the name says it is a simple tube
(commonly its length varying from 1,5 to 3 m)
which is pushed into the soil by the drill rig.
Depending on the type (loose, soft, cohesive,
etc) of soil (i.e. clay, sand, gravel) the core
barrel is simply pushed, pushed and rotated,
sometimes hammered or also pushed by vibrating
it. If the soil collapses (almost always) the
hole is cased with the casing drillstrings.Therefo
re the commoniest method to perform continuous
coring bore holes is an alternance of coring with
the core barrel and casing the previously cored
length of the hole, as shown in the following
picture
Coring and casing -sketch-
C coring R casing
THE CORE BARREL IS ALWAYS DRIVEN BY RODS WHICH
ARE SCREWED AND UNSCREWED EVERYTIME
STANDARD METHOD
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Advantages and disadvantages of using rods and
casing

• Advantages
• Simplicity of use
• idiot-proof operations
• low cost of the drilling tools
• No special requirements for water/mud pumps
• Fast installation of the drill rig

• DISADVANTAGES
• Poor quality of the cores (the friction with the
  inside walls of the core barrel sometimes causes
  burning and cementation of the core)
• Very often poor recovery (expecially in loose
  soils)
• Very slow operations by increasing the depth the
  more is the depth the more rods have to be
  screwed (to lower down the core barrel) and
  unscrewed (to retrieve the core barrel)
• Much more hand-power required (for
  screwing/unscrewing the rods hundreds times per
  day)
• Much more power required to the drill rig,
  expecially for the casing

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WIRE-LINE

• The recovery by cable or wire system (hence the
  name wire-line) is based on the use of a core
  barrel which, integrated with the casing, makes a
  sole body. Pushing and rotation are conveyed by
  the same casing.
• The system is essentially made up of
• Drilling rods (or "casing") inside which, at the
  bottom terminal part, there is an element
  (usually a slot) where the core barrel is lowered
  down by the wire and takes place inside, so
  allowing the drilling rods to rotate and push.
• Core barrel or drilling tool this is placed
  inside (throughout the interior of) the drilling
  rods and has a hook-up system.

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WIRE-LINE
Hooking system And Overshot
Mud pools in WL installation
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WIRE-LINE
NOT A SINGLE ROD IS SCREWED/UNSCREWED FOR
LOWERING AND RECOVERING THE CORE-BARREL ONLY THE
CASING RODS ARE SCREWED ONCE FOR DRILLING AND
UNSCREWED ONCE FOR RETRIEVING NO HAND-POWER
REQUIRED -IT IS COMPLIANT TO ALL SAFETY
REQUIREMENTS-
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WIRE-LINE details
HOOKING SYSTEM
Casing drill rods
Internal core-barrel OR no-coring assemply
OR Sampler OR special tool (medusa, CPT, etc) The
INTERNAL CORE-BARREL can be rotating Or not
rotating (having bearings under the Hooking
system preventing from rotation)
Water/mud flowing
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WIRE-LINE drill rig
BASICALLY THE DRILL RIG APPLIES ENERGY TO THE
CASING RODS IN FORM OF TORQUE (for
rotation) THRUST (for pushing and pulling)
AND WATER/MUD PRESSURE (for cutting the Soil
and lift the cuttings up)
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Lowering CB
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Lowering CB
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hooking
HOOKING (the corebarrel Latches inside The rods)
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CORING
ROTATION
PUSHING
WATER/MUD INJECTION
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END OF CORING
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INSERTING THE OVERSHOT
OVERSHOT
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LOWERING THE OVERSHOT
wire
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UNLATCHING THE COREBARREL
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Lifting the CB up
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Lifting the CB up
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Lifting the CB up
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Recovering the cb
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ADVANTAGES OF WIRE-LINE
NEARSHORE/OFFSHORE GEOTECHNICAL SURVEYS
C P T W D CONE PENETRATION TEST WHILE DRILLING (u
ses wire-line)
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ADVANTAGES OF WIRE-LINE

• Quality
• speed of execution almost independent from depth
• Flexibility (wide choice of tools can be used
  corebarrels, special tools, no-coring assembly,
  etc)
• The hole is ALWAYS cased
• Much less horsepowers are required to the drill
  rig (the casing is always rotating, no great
  friction outside the casing rods)
• SAFETY
• No hand-power is required, the Operators are
  not so much stressed
• Can be used in ALL type of soils (it was born for
  rock coring)

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DISADVANTAGES OF WIRE-LINE

• It is much more complicated than the simple core
  rods method
• it must be used ONLY by very-skilled (and smart)
  Operators
• The installation of the drill rig is very slow,
  more or less same time is required for a 15 m or
  150 m deep bore-hole!
• The drilling tools are much more expensive, so as
  the mud-pumps, pools, etc
• it is not raccomandable for shallow
  environmental surveys, because there is
  water/mud circulation (it might cause cross
  contamination)

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MEDUSA
Nothing to deal with jellyfish, but the way of
moving looks like it
Basically is a standard dilatometer (in terms of
sizes and principle of functioning) differently
from the standard equipment it is managed
electronically and the bottle of nitrogen is
contained inside a special wire-line
core-barrel. No tools are placed in the
surface, no manometers, no bottle just a
laptop, in order to download data and show on the
screen the operations It is used inside a
standard wire-line, whose outer diameter is 130
mm. Same wire-line can be used for continuous
coring, sampling, no coring (with or without
MWD), CPTWD.
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core barrel and Hooking system
Nitrogen bottle
electronics
GENERAL VIEW OF MEDUSA (underground)
50 mm diameter rods
DMT blade
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General view of the system
(above the ground)
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Photo 1
Wire-line Casing rods
DMT
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Photo 2
Internal Core barrel
Protruding Rods and DMT
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• The Medusa equipment functions as follow
• Inside the wireline casing rods is lowered the
  core-barrel containing the bottle of nitrogen,
  the electronics, and having the DMT protruding
  1,6-3,2 m (the lenght depending on some factors,
  such as (but not only) soil stiffness, thrust
  power of the drill rig, swelling or collapsing of
  the bottom of the hole, etc) prior of lowering
  it there is a synchronisation between the laptop
  and the electronics of Medusa. It is programmed
  the test (DEPTH, TIMES, ect)
• Once lowered the medusa core-barrel latches into
  the casing rods
• The operator knows that he must push the rods
  according to certain steps (pre-programmed rate
  of penetration) and stop the medusa every 20 cm
  of penetration IN THE LAPTOP IS SHOWN EXACTLY
  HOW THE MEDUSA IS MOVING ACCORDING TO THE TEST AS
  PROGRAMMED

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Electronics, synchronisation

• The electronics manages the bottle with a valve
  in such a way to
• enflate and deflate the membrane (exactly as the
  standard DMT)
• A pressure sensor detects the A and B values
• The values (time, A, B) are memorised into the
  internal RAM
• During the testing the laptop shows to the
  Operator how the medusa is moving
• Once the corebarrel is lowered and the brain is
  connected again to the laptop
• The software dowloads the A, B values

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BASIC OPERATIONS

• Prior to any pushing it has to be done the
  SETTING of the Medusa
• refilling/controlling the pressure of the
  nitrogen bottle
• Control the DMT and the membrane
• connecting the electronics to the laptop
• PROGRAM THE TEST

Electronics (microcomputer Inside the Corebarrel)
valve
LAPTOP
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SCREEN OF THE LAPTOPDURING THE TESTING
Time to Push0130
Making A
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Step 1
Drilling to depth -100 m by using one of the
following methods -no coring drilling (with or
without MWD) -continuous core -CPTWD -sampling or
testing
-100
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Step 2
-98,40
Lifting the rods up to -98,50 m And recovering
the drilling tool. The hole is always filled with
waterbentonite and/or polymers
Waterbentonite filling
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Step 3
Inserting the Medusa Core Barrel and latching
it Into the rods Prior to the inserting the
microcomputer inside the corebarrel is Resetted
and the synchronisation with depth is done
-98,40
N.B. the lenght of the rods protruding Out the
bottom of the drilling rods Should be a multiple
of 20 cm, normally varying From 80 to 320 cm, in
this case is 160 cm
-100,00
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Step 4
Pushing the medusa into the soil, with 20 cm
steps. After each interval (20 cm) the pushing is
stopped for a certain Time interval, allowing the
DMT test to be done
-100,20-101,60
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Step 5 a
END OF PUSHING
-100
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Step 5 B
END OF PUSHING And recovering the medusa Core
Barrel
Remoulded soil
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Step 6
INSERTING A CONTINUOUS CORE BARREL AND CORING
THE REMOULDED SOIL FOR CALIBRATION WITH THE DMT
RESULTS
Remoulded soil
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NEW WAY OF DMT TESTING

• WL MEDUSA WILL ALLOW TO ACHIEVE DMT DATA AT A
  GREATER DEPTH with no need to drill with rods
  (therefore in much less time)
• THE INTERPRETATION OF THE DATA IS AS PER THE
  STANDARD
• The tested ground can be cored so to have a
  qualitative evaluation
• The results are again not sensitive to the
  method of pushing

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• POSSIBILE FIELDS OF APPLICATION
• OF MEDUSA TECHNOLOGY
• Offhore drilling the possibility to obtain DMT
  data without using a static penetrometer on a
  barge together with the drill rig allows less
  costs and more reliable data at the same time.
• Testing in sites where the penetrometer is not
  usable (i.e. shallow gravel and then clay or
  silt/sand)
• Testing inside a bore-hole instead of using other
  unreliable and sometimes expensive kind of test

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The WL Medusa has been projected by Prof.Silvano
Marchetti Mr.Diego Marchetti -Engineer- Mr.Massim
o Sacchetto Engineer- THANK YOU