1. Washington D.C. 2nd-4th April 2006
D M T 2006
Washington D.C. 2nd-4th April 2006

2. WIRE-LINE MEDUSA
Electronic DMT for great depth

3. Drilling and coring Coring and casing -sketch-
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.Therefore 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

4. Advantages and disadvantages of using rods and casing
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

5. 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.

6. WIRE-LINE
Hooking system
And
Overshot
Mud pools in WL installation

7. 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-

8. 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

9. 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)

10. Lowering CB

11. Lowering CB

12. hooking
HOOKING
(the corebarrel
Latches inside
The rods)

13. CORING
ROTATION
PUSHING
WATER/MUD INJECTION

14. END OF CORING

15. INSERTING THE OVERSHOT

16. wire
LOWERING THE OVERSHOT

17. UNLATCHING THE COREBARREL

18. Lifting the CB up

19. Lifting the CB up

20. Lifting the CB up

21. Recovering the cb

22. ADVANTAGES OF WIRE-LINE
NEARSHORE/OFFSHORE
GEOTECHNICAL SURVEYS
C P T W D:
CONE
PENETRATION
TEST
WHILE
DRILLING
(uses wire-line)

23. 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)

24. 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)

25. 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.

26. “core barrel” and
Hooking system
Nitrogen bottle
GENERAL VIEW
OF MEDUSA
(underground)
electronics
50 mm diameter
rods
DMT blade

27. General view of the system
(above the ground)

28. Photo # 1
Wire-line Casing rods
DMT

29. Photo # 2
Internal
Core
barrel
Protruding
Rods and
DMT

30. 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

31. 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

32. BASIC OPERATIONS Electronics (microcomputer Inside the Corebarrel)
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

33. SCREEN OF THE LAPTOP DURING THE TESTING
Time to Push:01:30
Making: A

34. 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

35. Step 2 -98,40 Lifting the rods up to -98,50 m
And recovering the drilling tool.
The hole is always filled with water+bentonite and/or polymers
Water+bentonite filling

36. Step 3 -98,40 -100,00 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

37. 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
Step 4
-100,20……-101,60

38. END OF PUSHING
Step 5 a
-100

39. Step 5 B END OF PUSHING And recovering the medusa Core Barrel
Remoulded soil

40. Step 6 INSERTING A CONTINUOUS CORE BARREL
AND CORING THE REMOULDED SOIL FOR
CALIBRATION WITH THE DMT RESULTS
Remoulded soil

41. 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

42. 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

43. THANK YOU The WL Medusa has been projected by: Prof.Silvano Marchetti
Mr.Diego Marchetti
-Engineer-
Mr.Massimo Sacchetto Engineer-
THANK YOU