Pine Creek Airborne Electromagnetic Data Procedures … · Pine Creek Airborne Electromagnetic Data...

Pine Creek AEM Workshop March 2011

Pine Creek Airborne Electromagnetic Data

and

Procedures for AEM Data

Marina Costelloe, Ross Brodie, Mike Craig, Songfa Liu, Subhash Jaireth, Alan Whitaker, David Hutchinson,

Nick Williams and Ian Roach

Onshore Energy and Minerals Division


Survey location

GA Funded 19 500 line km

Industry Funded10 400 line km

Total~ 30 000 line km

Area75 000 km 2

Investment$3.7 million

Short term follow up exploration$2 million

Long term value of data$$$

EMFlow grids 40-60m (0-500 mS/m)

Woolner Granite

Kombolgie

Rum Jungle


Survey design

Rum Jungle

Woolner Granite

Kombolgie

Company infillvarious spacing200-1000m

TENEMENT SCALEDEPOSIT MAPPING

Darwin

Katherine

National Parks

100 km

GA 1.666 km linesNRETAS 555m lines

MINERAL SYSTEMS ANALYSIS

GA 5km lines

REGIONAL PERSPECTIVE

VTEM

TEMPEST


Survey Timing

May-09Flying completed

Oct-08Flying commenced TEMPESTTM De-mobilised for monsoon season

Milestones Risk/Delay

Pre-Survey planning started Mar-08

Flying commenced VTEMTM Test Flying (April 2009) Aug-08

Final data received from Contractor TEMPESTTM

Jul-09

Final data received from Contractor VTEMTM

Dec-09

Final data TEMPESTTM

RELEASED WEBSept-09

Final data VTEMTM

RELEASED DVD Dec-09

GA-LEI RELEASED TEMPESTTM WEB

2km EMFlowTM

RELEASED VTEMTM DVD

June-10

Dec-10


ConductivityTypical range of conductivities of common earth materials

Palacky (1993)


Conductivity

Pore fluid conductivity ( σw)Pore fluid saturation (s)Porosity (ø)Conductivity of solid matter ( σs)Pore size and arrangement (a)

LithologyStructureAlterationGroundwater

AEM responseExternal

information required for

interpretation

Slide provided by Richard Lane


Modelling

Q. Can we detect the targets?

200m

Milingimbi 1:250 000

Kombolgie Subgroup

Pine Creek Orogen

Geological ModelKombolgie/ PCO unconformity

Geological ModelTolmer Group /Finness River Unconformity

Pine Creek 1:250 000 sheet

Daly River GroupTolmer GroupFinniss River Group

Tempest

RUM JUNGLE Survey Data

VTEM

KOMBOLGIE Survey Data

200m


Step 1.

Save field data and check it against the contract specifications

Step 2.

Check the expected data has been supplied

Step 3.

High Altitude Noise analysis for whole survey (final flights)

Step 4.

Repeat line noise analysis

Step 5.

Create and check the line database and assess statistically all fields

Step 6.

Flight Path Checks

Step 7.

Terrain clearance checks

Step 8.

Altimeter correction checks

Step 9.

GPS Height field checks

Step 10.

Grid elevation and magnetic data

Step 11.

Grid EM data

Step 12.

Grid monitors and auxiliary data

Work Flow Diagram for the QA/QC of Field Processed AEM data

Step 13.

Compute and tabulate system geometry in detail

Step 14.

Preliminary GA inversions

Step 15.

Conductivity logging information

Step 16.

Other apriori information assessment and integration


Step 1.

Save final data and check it against the contract specifications

Step 2.

Check the expected data has been supplied

Step 3.

Check data format and metadata

Step 4.

Create and check the line database and assess

Step 5.

Flight Path Checks

Step 6.

Terrain clearance checks

Step 7.

Altimeter correction checks

Step 8.

GPS Height field checks

Step 9.

Grid elevation and magnetic data

Step 10.

Grid EM data

Step 11.

Grid monitors and auxiliary data

Work Flow Diagram for the QA/QC of Final Processed AEM data

Step 12.

Compute and tabulate system geometry in detail

Step 13.

Assess EM Flow data

Step 17.

Conductivity logging information

Step 18.

Other apriori information assessment and integration

Step 14.

Multiplot assessment

Step 15.

Logistics report and associated metadata (Geocat)

Step 16.

Final GA-LEI


Powerlinemonitor

Terrain Clearance Pitch and Roll

X EM noise monitors

X Windows

Z EM noise monitors

Z Windows

CDI Vertical Synthetic Section

Magnetics

Z 10 window data

CH 10 XWindow Data


Geoscience Australia Layered Earth Inversion

GA-LEI

DX

DZ

RXP

c1=10lc1 µ0 ε0 t1=10lt1

c2=10lc2 µ0 ε0 t2=10lt2

cNL=10lcNL µ0 ε0 tNL

= ∞

cNL-1=10lcNL-1 µ0 ε0 tNL-1=10ltNL-1

y-axis

z-axis

x-axis (0,0,0)

… … ... …

TXH

transmitter loop

receiver coils

tow cable

X-component coil

Z-component coil

RXH

horizontal plane

TXP

TXR

layer 1

layer NL-1

layer NL1

GA-LEI inversion framework

Unknowns to be solved for

Tow cable

Slide provided by Ross Brodie

Solves for conductivity and the unmeasured elements of the system geometry using the observed total field X and Z component data


10-5

10-4

10-3

10-2

10-3

10-2

10-1

100

101

Delay time (s)

Res

pons

e (f

T)

b) two layer model

X-componentZ-component

Data for one AEM sample1D inversion model for

each sample

Stitch all 1D models by gridding each layer conductivity

Depth slice −−−−average conductivity over constant depth interval

Elevation slice −average conductivity over constant interval relative to sea level

Stitch into a conductivity section for each flight line

Brodie and Fisher (2008).


Input

non-hprg data

Use

geological models

geo-electric models

Noise estimates

waveform

SBS ascii Depth

Slice

Elevation

Slice

Inversion Databases

CDI Sections

conductance

Grids

Depth_

Elevation_

create GoCAD and other products

Products

Located Data (SBS LEI ascii)

LEI CDIs geo-referenced

Grids micro-levelled (ERMapper)

Report (pdf)

3D

SBS (pdi)ascii

Assess inversion using surface geology solid geology drill holes gravity magnetics other information including conductivity logs.

Work Flow Diagram for the GA-LEI


RN20565

0

20

40

60

80

100

120

0 50 100 150 200 250

mS/m

Dep

th m

casing

Drillers log for RN205657-24m Grey Dolomite24-55 Grey/Brown Dolomite55-110 Grey DolomiteConductivity log for RN20565 Resistive

Conductive

Rx Property

Induction Conductivity LoggingFeed into forward modelsCross check AEM resultsUse for geological interpretation


Logging

(Steel casing)

Pine Creek AEM Workshop March 2011‘But the truth is in the drilling’

15km

100m

GA LEI

EMFLOW

GA LEI CDI compared to EM Flow TM CDIRum Jungle Tempest data CDI cross-sections

100mTx altitude

PDI or depth of investigation


Woolner Graniteand Rum Jungle

TEMPEST


125 km

N

Woolner Granite / Rum Jungle Depth Slice 80 - 100mTempest TM GA-LEI, various line spacing.

Masking


Woolner Granite / Rum Jungle Elevation Slice 300-290m bslTempest TM GA-LEI, various line spacing.

125km

N

Masking125 km

Base-10 logarithm (log10) of conductivity


Depth of Investigation (DOI)

N

125 kmLess than 50 m


Flight Path

1:1 000 000 Surface Geology strip

Top Surface isSurface Topography

GA-LEI cross-section TEMPEST TM data

Alluvial Plain

Bottom Surfaceno data

Basement conductorIsoclinal folding inMount Partridge Group

Rum Jungle Complex

Burrell Creek FM Mount Partridge Group South Alligator Group

Note: The PDI (depth of investigation) is deeper than 200m


Kombolgie survey areaVTEM

Pine Creek AEM Workshop March 2011N

Money Shoal Basin

McArthur Basin

Dunmarra Basin

Arafura Basin

Pine Creek Orogen

Kakadu National Park

100 km

(Colour range 0-500 mS/m)

Kombolgie Depth Slice 90-120mVTEMTM EM Flow TM, various line spacing.


World First Investigation depth to 2 000 m

Before Dec 2010600 – 800 m


World First Investigation depth to 2 000 m

Dec 2010


Magnetics (TMI RTP)

Surface Geology

EM FlowTM sections

Nabarlek

Kombolgie EM Flow TM cross-section

Basement conductor

Structure controlled mineralisation

Zone around unconformity

Basement Architecture


World First


ProductsPhase 1 data

ASCII Data - includes EM FlowTM

MultiplotsGridsAS delivered by the contractor

TEMPESTTM data available free on the GA websiteVTEMTM data is only available from the GA Sales centreReleased 2009

Multiplots

Grids

ReportandMetadata


ProductsPhase 2 GA LEI Woolner Graniteand Rum Jungle (TEMPESTTM)

ASCII data conductanceDepth slicesGridsAEM Go MapGeo-referenced CDI sectionsGA-LEI multiplotsAvailable free on the GA website Released 2010

AEM Go Map

Georeferenced JPEG(over conductance grid)

Report and metadata


Phase 2 Kombolgie (VTEMTM) to 2km data

ASCII dataDepth slicesGridsAEM Go MapEM FlowTM control filesGeo-referenced sectionsAvailable from the GA Sales centreReleased 2010

Kombolgie GA- LEI to be released July 2011

Grids


Summary

The Pine Creek AEM survey provides a regional picture by successfully mapping subsurface information through cover.

Geological features were mapped to depths below the Earth’s surface well beyond any previously recorded by AEM systems .

AEM can reduce exploration risks when used as a mapping tool.


www.ga.gov.au/energy/projects/airborne-electromagnetics.html

NOTE: ASEG-GDF2 files to accompany ASCII line data are available


AcknowledgementsGeoscience Australia sincerely thanks the following contributors

Richard Lane (GA) and Jim Macnae (RMIT)

Camilla Sorensen formerly GA) and Jon Sumner (NRETAS)Cameco Australia

Crossland Uranium Mines Ltd.

Energy Resources of Australia Ltd.

Hapsburg Exploration Pty. Ltd.National Water Commission

Natural Resources, Environment, The Arts and Sport

Northern Land CouncilNorthern Territory Geological Survey

Rio Tinto Exploration Pty. Ltd.

Rum Jungle Resources Ltd

Southern Uranium Ltd.Thundelarra Exploration

United Uranium Ltd.

Uranium Equities Ltd URANEX NL

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