Exploration of a sub-salt play in the Southern Amadeus Basin, Central - - PowerPoint PPT Presentation

Exploration of a sub-salt play in the Southern Amadeus Basin, Central Australia – searching for big gas in Proterozoic reservoirs

D.R. Johns, S. A. Menpes, P. Walshe and F. Bache Santos Ltd., 60 Flinders Street, Adelaide 5000, South Australia, Australia

SEAPEX 2017

Proterozoic Amadeus Basin, Northern Territory, Australia

Amadeus Basin – Neoproterozoic to Palaeozoic basin part of Centralian Superbasin

SEEBASETM 2014-2015 SEEBASE™

Seapex 2017

• Proterozoic – Palaeozoic sedimentary fill with several proven petroleum systems
• Targets are TCF-sized gas resource in conventional structures under Proterozoic evaporite seals
• Seismic program well advanced with drilling planned for 2019

Amadeus Basin; Wells, Seismic, and Infrastructure

Northern Amadeus Basin; Phanerozoic petroleum system, Mereenie and Palm Valley fields Southern Amadeus Basin; Proterozoic petroleum system, under explored.

50 km

Seapex 2017

• Thick, deformed Bitter Springs

evaporite sequence

• Thin, slightly deformed, Cambrian to

Devonian series above the Petermann unconformity:

• Some minor Alice Springs deformation
• Thick, strongly folded,

Cambrian to Devonian series above the Petermann unconformity:

• Strong Alice Springs

deformation

ERODED MUSGRAVE PROVINCE ARUNTA BLOCK UPLIFT SOUTH NORTH

Mereenie Palm Valley Surprise Dingo

S R S R R S R S S S S Dukas R S

Petermann unconformity

Basin shape

Amadeus Basin; Conceptual Play Cross Section

Proterozoic section in the south, Palaeozoic section in the north

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Structural framework: summary 2 3

Amadeus Basin; Tectonic Elements

Three tectonic trends influenced basin development

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Petroleum systems and play intervals

Southern Amadeus Basin Key Wells

Wells in the south have penetrated a thick Proterozoic evaporite sequence and two wells Magee-1 and Mt Kitty-1 have tested gas from below the evaporites

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Neoproterozoic Sub-salt play

Gas flows from Magee-1 (1992) and Mt Kitty-1 (2014) have proven the sub-salt petroleum system

Magee-1 OHT Mt Kitty-1 OHT

• 2 wells have tested the sub-salt play, both flowed hydrocarbons  proven petroleum

system

• Highly competent regional evaporite seal
• Material Helium, elemental H, valuable by-products

50 km

Magee-1 Mt Kitty-1

Seapex 2017

Heavitree Play Interval (1) - Outcrops

S R S

50 km

Basement (Heavitree absent)

Basement thrust

Magee-1 Mt Kitty-1

Heavitree 6.3 m

Ellery Creek

Heavitree Sandstone; Regional context

The Heavitree/Dean Quartzite ranges from 200m to 1000m thick North and South of the Amadeus

• Basin. Likely deposited as an extensive sheet sandstone in the Centralian Superbasin

Seapex 2017

Amadeus Basin Exploration Program

1300 km planned 2D seismic program to mature opportunities for drilling in 2019

Seapex 2017 2013 2D Seismic Survey

• First regional 2D seismic
• 1586 line km over 43,000 sq km
• Line length up to 387km

Objectives

• Provide regional structural and

stratigraphic framework

• Link isolated 2D grids
• Identify key leads for follow up

2016/7 2D Seismic Survey

• 1300km of seismic infill ; 932km

acquired, remainder later in year

• Acquisition and processing

parameters modified

• Longer offsets, higher sampling,

longer sweep length, infield and fast-track processing

Southern Amadeus Basin; East-West Regional Strike Line

W

• Gradual shallowing of interpreted basement/near top Heavitree Fm; onlap and thinning of

Neoproterozoic section towards the SE basin margin

• Significant seismic wash-out zones in areas of thick salt and/or intense halotectonics
• Imaging of very thick Mesoproterozoic pre-Amadeus unit – potential proto-Amadeus rift succession?

10 km

Magee-1

E

Gillen Salt

Mesoproterozoic pre-Amadeus unit

Near Top Heavitree Petermann Unconformity

ms

Salt disturbed zones

Section (386km) demonstrates thinning and onlap of Neoproterozoic section to East

Seapex 2017

Southern Amadeus Basin; Lead B updip of Magee-1

Lead B - updip of Magee-1 (1991), wet gas flow from sub-salt play

Seapex 2017 10 km

Magee-1

NW SE

• Thinning of Neoproterozoic unit onto the SE basin margin
• Mesoproterozoic pre-Amadeus unit is better imaged where basement is shallow and Gillen salt is thin and

undeformed

Gillen Salt Chandler Salt Lead B Near Top Heavitree

Mesoproterozoic pre-Amadeus unit

ms

AMSAN13B-06

Southern Amadeus Basin; Sub-salt Play-Trap

Central arch a long term regional migration focus, speculative rift precursor basin remnants in western sector, stress regime more favourable

10 km

Murphy-1

S

• Central High Lead part of regional sub-salt basement high and likely migration focus
• Difference in deformation style between south and north
• South  Detached thrust faults related to early Petermann Orogeny & relatively

undeformed Petermann U/C

• North  Phanerozoic deformation as a result of Devonian Alice Springs Orogeny, does not

extend south of central high

Central High Lead (Lead A)

Detached Petermann Orogeny faults Meta(?)sedimentary precursor basin section (?) affected by Petermann Orogeny reverse faults

Petermann Unconformity Gillen Salt Near Top Heavitree

ms

Seapex 2017

Southern Amadeus Basin Sub-salt Play - SEAL

Evaporites – Highly competent seal traps H, He and hydrocarbons and protects from tectonic breaching

• Thick Cambrian evaporite seal has taken

up tectonic deformation, protecting underlying hydrocarbon accumulations from tectonic breaching

• Effective top seal traps He (0.2% in

Yurubcheno-Tokhomskoye Field)

• Multi-TCF gas fields and billion bbl oil

fields

East Siberia

E W

Amadeus

• Thick Neoproterozoic evaporite seal has

taken up tectonic deformation, protecting underlying hydrocarbon accumulations from tectonic breaching

• Effective top seal traps H and He (Mt

Kitty and Magee accumulations)

• Multi-TCF gas opportunities

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Southern Amadeus Basin; Sub-salt Play - RESERVOIR

Gas flows from natural fractures in granite and pre-salt carbonates

3 km

Mt Kitty

Petermann Unc

#1 #2 #3 #4

Flow Tests

Top Basement

Flow test #2

Basement Fractures Image Log First significant gas below evaporite succession from fractured Lower Gillen dolomite

Flow test #2 10m

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13b08

Upper Gillen Upper Bitter Springs

Petermann unconformity

SW NE

S R S

Gillen Play Interval (2 and 3)

Southern Amadeus Basin; Raft Play

Rafts are made of (probable) Upper Gillen dolomite that sank into the Gillen halite in the core

• f anticlines

Erldunda-1

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Seismic Reprocessing – AMSAN 13b-04

Enhance imaging of sub-salt reflector and supra-salt section

Original Processing - 2013 Reprocessing - 2017

Gillen Play Interval (2 and 3)

Southern Amadeus Raft Play; South Oman Analogue

Rafts within salt section of the Southern Amadeus Basin compare favourably with Dolomite stringers in Salt from South Oman

Seapex 2017

+ Hydrocarbons have been generated and trapped below sealing Neoproterozoic evaporites in the Southern Amadeus Basin + Large structural features are present that are currently being defined by a seismic acquisition program currently underway + The Heavitree sandstone is the primary target; regional evidence points to a fluvio-marine sheet sand

• nlapping and to the east and thickening into the basin to the west

+ Secondary targets are Gillen dolomites present as rafts within the evaporites. There are analogies with the South Oman late Phanerozoic to Palaeozoic dolomite ‘stringer’ play + Seismic acquisition will be resumed in the 3rd quarter 2017 with the intention of further defining targets for drilling in 2019

Summary and Conclusions

Seapex 2017

Acknowledgements

+ The authors wish to thank current and past members of the Southern Amadeus Exploration team, Santos Regional Exploration team and Santos’ Operation Geophysics team + Santos also acknowledges and thanks the exploration team of our partner, Central Petroleum. + The authors wish to thank Santos for permission to present this presentation

Seapex 2017