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Electronic DMT for great depth Drilling and coring For shallow continuous coring bore-holes the commoniest method is using the simple tube core barrel.

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Presentation on theme: "Electronic DMT for great depth Drilling and coring For shallow continuous coring bore-holes the commoniest method is using the simple tube core barrel."— Presentation transcript:

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3 Electronic DMT for great depth

4 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.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

5 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

6 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.

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

8 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-

9 WIRE-LINE details 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) HOOKING SYSTEM Water/mud flowing

10 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)

11 Lowering CB

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13 HOOKING (the corebarrel Latches inside The rods) hooking

14 ROTATION PUSHING WATER/MUD INJECTION CORING

15 END OF CORING

16 OVERSHOT INSERTING THE OVERSHOT

17 wire LOWERING THE OVERSHOT

18 UNLATCHING THE COREBARREL

19 Lifting the CB up

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22 Recovering the cb

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

24 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 )

25 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)

26 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.

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

28 (above the ground) General view of the system

29 Wire-line Casing rods DMT Photo # 1

30 Photo # 2 Internal Core barrel Protruding Rods and DMT

31 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

32 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 Electronics, synchronisation

33 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

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

35 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 Step 1

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

37 -98, ,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 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 Step 3

38 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 Step 4

39 END OF PUSHING -100 Step 5 a

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

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

42 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

43 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

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


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