AIG‐ADIA Drilling for Geology seminar 1/8/2014
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An Overview -Most Commonly Utilised Drilling Methods and their Applications within Australia
Welcome and Introduction
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Overview Drilling Industry Sectors
Fundamentals of Drilling a hole
Drilling Methods
Drilling Rigs
Summary of Drilling Methods and their Applications
Drilling Industry Sectors Geotechnical Foundation / Construction Mineral Exploration Blast Hole / Seismic Water Well Environmental Oil and gas Over Water and Offshore
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Why do you need to drill a hole? What are you hoping to achieve –
• Detailed geology or Basic overview?• Sample retrieval?
• Type of sample – soil / core?• Disturbed / undisturbed?• Size of sample?• In-situ testing?
• Installing monitoring equipment?• Simply a hole eg. for foundations • How deep?• What diameter?• Where….?
Drilling Fundamentals Drilling or penetrating the ground effectively
Effective clearing of the hole
Stable walls
Information Gathering Techniques –
Applications requiring coring / sampling
Well construction applications
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Drilling Methods Auger drilling – solid flight / hollow stem
Washbore / Mud Rotary Drilling
Coring – Conventional and Wireline
Sonic
Direct Push
Air Rotary - RC – Reverse Circulation
RAB – Rotary Air Blast / Percussion /Hammer
Auger Drilling Piling – large diameter, soft
ground Geotechnical - Generally only
used for shallow holes <10m Solid Flight Hollow Stem – continuous
undisturbed samples Can come in a variety of sizes
– 50mm and up Tungsten Carbide bit (TC) Will refuse in large and tight
gravels, cobbles, boulders and rock.
No drilling medium needed
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Washbore / Mud Rotary Used in geotechnical drilling and
for deeper holes in unstable strata
Water is the drilling flush/medium to help bring cuttings to the surface
Drilling muds / additives are added to help hole advancement and stability
Suitable for un-consolidated and some low strength consolidated formations
Variety of bit types Water is generally recycled by
way of tanks or pits Potential mess on completion, Can be harder to log strata
Coring Best applied in consolidated
formations
Various sizes – eg. NLMC, HQ, PQ
All hole depths
Wire line coring – can be faster than conventional coring depending on depth and strata
Ideal for samples for strength testing and detailed logging
Air and water can be used as a medium
Can be slow depending on strata and depth
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Sonic Drilling Rotary vibratory drill Liquefaction of soils and
overburden – utilised in unconsolidated and consolidated materials including boulders
Continuous samples – soil and rock.
In rock water is added to speed up the drilling
Fast – 10m / hour Minimal sample loss Quiet Minimal waste Relatively new technology Potential alteration to borehole
permeability Limited depth range
Direct Push No Cuttings
Undisturbed samples
Fast – 2-8m per minute
Smaller diameter holes
Small rigs – useful for difficult / tight access
Probe attachements also available – similar to CPT probe
Limited depth range
Only suitable in unconsolidated ground
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Air RotaryCommon in exploration and water drilling• Fast• Chip samples only• Suitable in both unconsolidated and
consolidated formations• Easy to determine water strikes• Water and additives can be added
to aid drilling and stabilise the holes• It is possible to erode the borehole
wall and samples are more easily contaminated
RC -Reverse Circulation – cuttings lifted out of the hole up the drill string –Fast Cuttings contained Better quality –less contaminated
RAB – Rotary Air Blast / conventional circulation Fast Can be messy
Efficiency – Which rig and technique should I use?Which Method will get me the results I need- quickly, is most cost effective but without loosing quality?
Factors to consider: Strata Depth and diameter – will casing need to be run? Samples – frequency and type Budget Site constraints
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Unconsolidated Formations
Auger Drilling –Cheap and fast
Rotary Mud – Fast penetration rates
Rotary Air – Very fast in dry cohesive formations
Firm but stable formations – high
drillability
Rotary Air / Mud –good results
Hammer – Chip and water sampling, fast penetration
Diamond Coring –Slower than hammer but V good samples
Consolidated –Low drillability
Hammer – fast penetration (Top hole hammer – shallow holes, down hole hammer deeper holes)
Diamond Drills – more info + core
Rotary – fast and cheap
Drilling Boulders and difficult ground
Casing advance systems
Hammer – breaks boulders up
Sonic - drills straight through obstructions
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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ExamplesGeotechnical hole:Sampling every 1.5m Utililsing Auger, wahsbore and coring Expect 20-30m a day on averageExploration open hole:Mud/Air RotaryChip samples every 1.0mExpect 60 – 200m a day depending on casing requirements and hole diameterSonic Hole:Continuous sampleUp to 10m an hour
In each case the speed is often dictated by the ground conditions and size of the drill rig and the drillers experience.
Quality
Right rig for right job
Experienced and licensed driller and crew
Time
Well maintained equipment
Budget
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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PriceMany factors to consider: Depends on the drilling application – Techniques do
affect cost-• Geotechnical – less meters in a day = higher meterage
rate and more items• Exploration – more meters achievable in a day = lower
meterage rate Details of the job – mine site, brownfield or greenfield
site, access, distance between holes etc etc… all must be factored in when pricing a job.
Size of the drill rig
Meterage V Day Rate - Day Rate Client takes on the risk meterage the driller takes the risk
Auger RigsSmall to large in size, variety of carriers
The larger the auger the larger to rig
Most multipurpose rigs also have auger capabilities as do some excavators – various diameters –can be an alternative to test pits on restricted access sites
4x4 mounted rigs often used for shallow Geotech investigations
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Comparison
Solid Flight Hole must support
itself Cuttings are bought to
surface by the helical flights
Low equipment costs and set up
Accurate water strikes
Hollow Stem Secondary internal rod
therefore hole is continually supported
Wireline and overshot commonly used to retrieve samples and run testing equipment
Higher cost to set up than solid flight
Slower than solid flight
Rotary Air /Mud
Truck or Track MountedGenerally large in order to be able to drill deeperCan be multi – purpose - auger, washbore and coreSome are purely air rotary sucj as the RC rigs (not common in QLD – more often used for heavy metal / mineral exploration)
Most common applications –exploration, geotechnical, environmental monitoring, water well
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Comparison 2
Mud Rotary Mud helps stabilise the
hole – less erosion of bore walls
Lifts cuttings / samples quicker to surface
Helps keep bit cool and cutting action cleaner
Preferred on gas sites
Air Rotary Better in consolidated
ground Fast More equipment –
compressors Better quality samples
– can be easier to log
Sonic and Direct PushSpecialised methods Truck or track mountedVarious sizes and appearances –similar to muti-purpose rigs in appearance – have a different head assembly.May require less support
equipment than conventional drill rigs
Not as common as conventional drill rigsApplications – Geotech, Environmental and difficult drilling – boulders, landfill etc.
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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The Geologist’s Role on Site Give information and instruction to the driller –
COMMUNICATION IS KEY!
Understand the drilling method and understand the basic principles of drilling a hole
Understand the sampling methods and procedures
Try not to p**s the driller off!!!!
Summary Auger – geotech, piling, shallow investigations
Mud rotary – geotech, deeper unconsolidated formations, exploration gas sites, offshore
Air Rotary – consolidated formations, environmental, exploration, water well, blast holes and seismic
Direct Push – shallower environmental investigations, geotech
Sonic – geotech, environmental investigations
AIG‐ADIA Drilling for Geology seminar 1/8/2014
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Summary The best drilling method depends on the type
of job and results that are needed
Every hole is different
Communicate clearly what you expect from the investigation
Cheapest and quickest method may not save you money in the long run
More information Speak with drilling companies direct
Get in touch with ADIA
Reading material “Drilling The Manual of Methods, Applications and Management” Produced by Australian Drilling Industry Training Committee Limited
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