Applied Mineralogy and Non-Metallic Resources I ... · PDF file2 Applied Mineralogy and Non-Metallic Resources I Introduction / Exploration How do we find new resources? “In my view

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Applied Mineralogy and Non-Metallic Resources I Introduction / Exploration

Exploration


Why do we need natural resources?

average increase in demand: 5 % per year

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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 Elli Ch i f BHP A t li 1998J.K. Ellis, Chairman of BHP, Australia 1998


How do we find new resources? Geological methods:

S i l i f l

Reality is: hard work

• 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 l i l h i l d h i lgeological, geochemical and geophysical

parameters

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How do we find new resources? Pre-study

Reconnaissance exploration

D t il d f ll l tiDetailed follow-up exploration

Evaluation


How do we find new resources?

• What is beneath our feet?

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DrillingRotary 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

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• Drill bit



• Modern drill rig for deep drilling

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DrillingSchematic sketch ofSchematic 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

M M M

250m³/h

250m³/h

DrillingRotary drilling

300m³/h

2mm

0,10mm

M M M

100m³/h

Rotary drilling

• Mud flow

0,10mm

0,10mm

M M

0,02mm

15m³/hM M

0,02mm

15m³/h

100m /h

100m³/h

100m³/h

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DrillingMud flow in boreholeMud 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)


Core drilling

• Drill core “growths” inside the 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

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DrillingDirectional drilling

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

http://www.sbo.at/cms/cms.php?bl=3&sid=ln1q8euop95lb08ra3n694dc8/

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 CirculationReverse Circulation(RC)

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

DrillingReverse Circulation

• 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

Reverse Circulation(RC)

tube

• Air passes through a cyclone for separation of cuttings



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• Iron ore exploration(Western Australia)


DrillingDiamond core drillingg

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

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DrillingDiamond core drillingDiamond core drilling

• Wireline core drilling (iron ore exploration , Cameroon)



• Drill bits for diamondcoring

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Wireline coring

• Drill core “growths” inside inner tube

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

b lcore barrel

• Retrieve the inner tube with the core


Wireline coring

• Inner tube with latch head

• Overshot tool

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• Drill cores in core boxes


Borehole deviation

• Where does your borehole go?

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Borehole deviation • Drill rods become increasingly flexible

• Torque of the rotating bit works against cutting

• Why do boreholes deviate?

Torque of the rotating bit works against cutting face

• Reaction of bit to foliation and structure of rock, as well as drilling through different rock layers of varying resistance

• Deviation also depends on the drilling technique


Borehole deviation measurement

Magnetic measurement based on earth magnetic field and gravity (inclination)

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Borehole deviation measurement

Non-magnetic survey with tools based on gyro technology or on deflection measurement


Borehole deviation

• Deviation of vertical borehole

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Borehole deviation

• Deviation of inclined borehole


Borehole deviation • A new Cu-/Zn-deposit was found in 1989 in the province of Quebec with drilling to a depth of

• Case story830 m

• The deposit was estimated to be 30 million tons of or consisting of 3.1 % Cu and 1.34 % Zn

• An underground drilling campaign was carried out after excavation of shafts and drifts

Result: a deposit of only 15.7 million tons was confirmed

Explanation: important deviation of boreholes drilled from the surface

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Demonstration of a gyro tool

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Applied Mineralogy and Non-Metallic Resources I ... · PDF file2 Applied Mineralogy and Non-Metallic Resources I Introduction / Exploration How do we find new resources? “In my view