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Applied Mineralogy and Non-Metallic Resources I Exploration/Drilling

ExplorationDrilling Techniques


Why do we need natural resources?

average increase in demand: 5 % per year


How do we find new resources?

“In my view the greatest value is added by the geologist who starts with nothing other than some ideas and goes out into the desert and finds an orebody.”

J.K. Ellis, Chairman of BHP, Australia 1998


How do we find new resources?Fun!

Reality is: hard work!

Geological methods:

• Systematic exploration of larger areas

• Exploration in geological environment found to be similar to known deposits

• Improved geological interpretation and analysis of existing data

• Development of exploration model based on geological, geochemical and geophysical parameters


How do we find new resources? Pre-study

Reconnaissance exploration

Detailed follow-up exploration

Evaluation


How do we find new resources?

• What is beneath our feet?

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Example:

Geothermal Energy Project St. Gallen

Pre-study:

Seismic Field Campaign


Example:


Pre-study:

Interpretation of seismic measurements


Example:


Exploration:

Start of drilling: Monday March 4, 2013


DrillingRotary drilling

• Oil field rig


Drilling1. Mud tank

4. Mud pump

7. Winch

14. Derrick/mast

16. Drill rods

20. Rotary table

23./24. BOP

26. Drill bit



• Deep water wells(Palestine)

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• Rotary table with opening for the “kelly”

• Drive mechanism



• Drill bit (Trycone)


DrillingRotary drilling –

Some details



• Modern drill rig for deep drilling


DrillingSchematic sketch of modern drill rig for deep drilling

• Top drive instead of rotary table


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• Pipe handler


chute with1,5% incline

300m³/h

2mm

300m³/h

0,10mm

0,10mm

0,10mm

M M

0,02mm

15m³/hM M

0,02mm

15m³/h

M M M

M M M

250m³/h

250m³/h

100m³/h

100m³/h

100m³/h


• Mud flow



• Spindle drive



• Spindle drive



• …no need to be verybig!


DrillingMud flow in borehole

• Pumped down the drill string

• Raises in the annulus

• Cooling of the drill bit

• Carries the cuttings to the surface

• Prevents from blocking the string (thixotropy)

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DrillingDirectional drilling

http://www.sbo.at/cms/cms.php?pageName=61&movieQuality=hq&sid=4403c274e1c7f695bfe7557383878f36

• The drill string becomes flexible when drilling very deep boreholes direction cannot be maintained

• A downhole motor (positive displacement motor PDM) is used for driving the drill bit

• The mud flow drives the PDM

• MWD (measurement while drilling) allows continuous directional control of the drill bit

• Allows drilling of several wells from 1 drill site (most often applied in off-shore drilling)


DrillingReverse Circulation(RC)


• A pneumatic reciprocating piston (hammer) drives the a tungsten-steel drill bit

• Working with large air compressors, the drilling produces dry rock cuttings

• Dual wall drill rods are used to inject air and to produce cuttings through the drill string

• Air is blown down the rods (annular space) and air, water and cuttings are lifted inside the inner tube

• Air passes through a cyclone for separation of cuttings






• Iron ore exploration(Western Australia)


DrillingDown-the-hole-hammer drilling (also Rotary Air Blast drilling – RAB)

• Pneumatically reciprocating piston-driven hammer

• Cuttings raise in the annulus

• Efficient drilling technique

• Used in exploration, blast-hole drilling, water wells, geotechnics

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DrillingDown-the-hole-hammer drilling (also Rotary Air Blast drilling – RAB)

• Commonly used drilling technique for ground heat pumps

• Depth is limited by maximum pressure of compressor


DrillingAuger drilling

• Drilling in unconsolidated ground, in soil or in weathered rock

• e.g. for bauxite exploration


DrillingDiamond core drilling

• Wireline core drilling (gold exploration , Quebec, Canada)


Drilling

Diamond core drilling

• Drill core “growths” inside inner tube

• Retrieve the entire drill string to recover inner tube with the core

• Core lifter case at bottom end of inner tube prevents the core from falling out



• Wireline core drilling (iron ore exploration , Cameroon)



• Drill bits for diamondcoring

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Wireline coring

• Drill core “grows” inside inner tube

• A overshot tool is lowered on the wireline to unlatch the inner tube from the core barrel

• Retrieve the inner tube with the core


Wireline coring

• Inner tube with latch head

• Overshot tool


Wireline coring

• Inner tube

• Overshot tool



• Drill cores in core boxes


DrillingLarge diameter drilling

• Accident in Mina San JoséAugust 5, 2010



• Raise bore technique

1. Drilling of a pilot hole

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• Raise bore technique

2. Drilling of a shaft



• Raise bore machine



• Raise bore head



• Down-bore technique

Shaft sinking from top



• Rescue of Chilean miners



• Rescue of Chilean miners after 69 daysOctober 13, 2010

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