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7/28/2019 Articulo Natalia 2

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A surface NMR study for groundwaterresource assessment in the Uley

Basin, South AustraliaAaron Davis, Tim Munday, Jacqueline Frizenschaf and Nara Somaratne

CESRE/ WATER FOR A HEALTHY COUNTRY


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Purpose of study

Use hydrogeophysics to refine the model for Uley South Lens

Better define aquifer thickness, geometry and hydraulicproperties in areas where little information exists.

Determine the depth to groundwater, aquifer porosity anhydraulic conductivity

Determine whether aquifer bounds could be revised in GW

model

A surface NMR study for groundwater resource assessment in the Uley Basin, South Australia

Trial non-invasive approachto examine as a pre-cursor todrilling


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Approach

Employ surface Nuclear Magnetic Resonance (sNMR) andTime Domain Electromagnetic (TDEM) soundings in the SWcorner of Uley South Lens



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Why use NMR?

The only geophysical technique that allows for direct detectionof water in the subsurface

Non-invasive

Minimal environmental footprint

Less expensive than exploratory drilling

Estimate

Water content

Aquifer porosity

Hydraulic conductivity



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Eyre Peninsula and Uley South

Only few aquifers

provide potablewater to EyrePeninsula

Uley South is

most importantone

Supports PortLincoln and eastcoast of the Eyre

2007-2008 waterallocation was~7200 Ml


100 km


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Uley South groundwater lenses

Port

Lincoln

Coffin Bay

Coffin Bay

National Park

Uley South

Coffin Bay A

Uley East

Uley Wanilla


25 km


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Eyre Peninsula and Uley South Quaternary limestone

aquifers in the very

near surface

Rainfall dependent forrecharge (~500 mm/a)

Water levels had beendropping frombeginning ofproduction until 2008


Begin of extraction

Reduction of pumping

6028-00754


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Uley South lens recharge

Recharge is generally through sinkholes directlyinto the Quaternary Bridgewater formation

Water age can be as little as 60 days



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Conceptual hydrogeological model

Source: EPNRM



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Previous work: TEMPEST AEM Fitzpatrick et al, 2009

Tempest AEM survey Basin and aquifer geometry

Possible connection betweenCoffin Bay A and Uley South

Thickness and extent of UleySouth and Coffin Bay Afreshwater lenses

Confirmed seawater

intrusion to extent of ~700 min Uley South



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Theres water in the hills: Elevation


10 km


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Magnetics - basement geometry


10 km

Basement highs


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10 km

Interval Conductivity -23 mAHD

Basement highs


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Planning of soundings


Inferred directions ofgroundwater flow

(Quaternary Limestone)

10 km


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Planning of soundings


10 km


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sNMR & TEM Soundings

Vista-Clara GMR

Single-turn 72.5 m loop

Aligned with magnetic North (-67.4 inclination, ~59000 nT)

~2530 Hz

Depth of penetration/resolution ~60 m

NanoTEM

Operating at 32Hz

40 m loop

Depth of penetration ~80 m



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sNMR: Site 3


10 km


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sNMR: Site 3 Sounding data



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sNMR: Site 3 Inversion


ULE098 is 460 m away from Site 3


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sNMR: Site 6


10 km


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sNMR: Site 6 Inversion


ULE208 is 240 m away from Site 6

No

cutting

returns


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sNMR: Site ULE193


10 km


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sNMR: Site ULE193 Inversion


~450 m/day


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sNMR: Comparisons


6 3


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sNMR Sections (with AEM)


10 km


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N S


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N S


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ConclusionDetected water in:

Quaternary aquifer (Bridgewater Formation)

FREE WILLY, porosity ~20%, HIGH k VALUES?

Partially constrained by Uley Formation

Tertiary aquifer (Wanilla Formation)

Mainly mobile, partly bound, porosity ~20% More saline than Bridgewater

AEM and sNMR assist in hydrogeological interpretation

Produce a section that shows extent of formations

Refined conceptual understanding of aquifer system and variation inaquifer characteristics, which provide opportunity to update GWmodels and management options.



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Future planning of soundings


10 km


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Thank youEM ApplicationsDr Aaron Davis

Senior Research Geophysicist

t +61 8 6436 8951

e [email protected] www.csiro.au

WATER FOR A HEALTHY COUNTRY

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