Post on 08-Jul-2016
description
1
The Turbodrill -
An introduction
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Typical Steerable Turbine
3
Forces and Load Support
4
Moving Disc
Fixed Disc
Moving Disc
Spacer Front Bearing
Labyrinth
Thrust Bearing
Flexible Shaft
Bent Housing
Front Bearing Stabiliser
Bit Box Stabiliser
Turbodrill Bearing Section
Thrust Bearing Components
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PDC Thrust Bearing
( …or, animated…….)
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Turbodrill features…
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Leakage Flow Exits to Annulus
Turbine Shaft
Pressure Equalising Leakage Flow
Micro Annulus
Balance Drum
Housing
Main Mud Flow into Turbodrill
Balance Drum Assembly
Motor Section
Main Flow to Motor Section
Turbodrill Balance Drum Assembly
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Downhole motors: Turbodrill competitors…
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Turbodrill and PDM Drive Function
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PDM Main Technical Features
• Torque / Speed range defined by lobe ratio• Slow enough for tricone bits• Torque variable via WOB• Low pressure demand on rig pumps – 150 psi per stage• Most technology available “over the counter”• Relatively easy to build adequate tool.
But… . . .
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PDM Main Technical Features, continued
But… . . .
• Motor section limits life and power• Significantly affected by temperature• Readily damaged by stalling• Hydraulic noise, poor radial balance affects MWD
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Turbodrill Technical Features
• Very high power potential• Intrinsically reliable / Long Life• Near perfect radial balance• No reliance on elastomers for power I.e. heat-proof• Fluid coupling effect.
But… . . .
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Turbodrill Technical Features, continued
But… . . .
• Speeds too high for tricone bits• High power output - at expense of flow rate • Little application in top hole?• Building a viable and reliable turbodrill is difficult.
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PUMP PRESSURE DISTRIBUTION12-14" HOLE SECTION
0
500
1000
1500
2000
2500
3000
3500
4000
4500
500 550 600 650 700 750 800 850 900 950
FLOW RATE (GPM)
PRES
SUR
E (P
SI)
Available For TurbineParasitic Losses
Following On…..
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Turbodrill & PDM . . . .
. . . .What’s the difference?
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Well bore quality
17Borehole Image with typical profile
generated by PDM + RockbitBorehole Image with typical profile
generated by Turbine + long gauge bit
Reduced hole spiralling effects & smoother well bore.(Hole spiralling negatively impacts measurements, mud, cement, casing running, etc.)- data from image tools would indicate less spiralling than competitors (primarily PDM’s + Rock BIts)
Well bore quality: smooth ? …
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Well bore quality: Hole Spiralling 1…
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Well bore quality: Hole Spiralling 2…
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Well bore quality: Hole Spiralling problems…
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LONG GAUGE PIN CONNECTION.
NEAR BIT STABILISER.
BOTTOM BEARINGSTABILISER
BOX END SHAFT
LONG GAUGE PIN CONNECTION.
SHORT GAUGE PIN CONNECTION
BOX END SHAFT
BIT BOXSTABILISER
BOTTOM BEARINGSTABILISER
BOTTOM BEARINGSTABILISER
BOX-UPLONG GAUGE BIT.
BOTTOM BEARINGSTABILISER
4.6Ft *
2.6Ft *
2.2Ft*
1.4Ft*
(* typical- may vary)