Transcript Managed aquifer recharge complimenting irrigation as

Managed aquifer recharge
complimenting irrigation as
beneficial re-use of coal seam gas
water
Irrigation Australia Conference
Workshop 15 – Development of non-traditional water sources for irrigation
Thursday 5th May 2014
David Gornall – Hydrogeologist
Yestin Hughes – Surface Facilities Water Engineer
Santos GLNG Project area
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Santos GLNG Project scope
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CSG to LNG Project with key upstream
assets:
– Fairview
– Roma
– Arcadia and Scotia
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Water Management for Each CSG
Field
Compression Facilities and Gas
Transfer Pipelines
2 Train LNG facility at Curtis Island –
Gladstone
Focus today is water management
for the Roma CSG Field
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CSG water re-use options
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Depressurising the coal seams is achieved by pumping large volumes of groundwater
from coal seams.
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The CSG industry is required to beneficially re-use this water, where possible, via one
or a number of options including:
– dust suppression;
– rehabilitation and environmental restoration;
– municipal and/or industrial use;
– irrigation/farm use; or
– managed aquifer recharge.
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CSG water re-use options
Selection is constrained by :
– Location
• The transport of water is uneconomic. Typically, we do not transport >30km.
• Municipal/industrial re-use is precluded in most situations (GLNG project area
is far from towns and industries).
• Similarly, not all CSG fields have aquifers that are suitable for re-injection via
MAR.
– Demand
• Volume and rate of CSG water production is variable throughout the life of the
project.
• Solution must be able to handle the peak water production in first 5-10 years, or
else the solution requires alternative capacity.
• Oversizing the water re-use option to handle the peaks may be uneconomic; bulk
of the re-use capacity will redundant.
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CSG water re-use options
Selection is constrained by:
– Water Quality
• Minimising the treatment capacity at the peak of CSG water production is
the best option.
• Treatment is typically only to remove slight brackishness – it is a question of
dilution.
• For example,
– Seawater ~35,000 mg/L
– CSG water 1,500-10,000 mg/L
Treatment and/or
amendment
Irrigation <2000 mg/L
(typical)
Treatment required
MAR <1000 mg/L
(aquifer dependent)
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What is managed aquifer recharge?
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“Purposeful recharge of water to aquifers for subsequent recovery or environmental
benefit.”
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Our source of water for recharge:
– Treated CSG water via Reverse Osmosis.
– Actually too clean.
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Advantages of MAR as a re-use option:
– Reliable capacity (i.e. not dependent on rainfall/climate).
– Small physical footprint.
– Benefits all those who abstract groundwater in the region (~5km radius)
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What is managed aquifer recharge?
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Roma MAR – injection target
Gubberamunda Sandstone
- Outcrop in the north
- Dipping south south-west
Zone of typical water
bore locations
Gubberamunda
surface outcrop
Roma MAR
injection site
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Increase in groundwater levels
10 km
Landholder bores in the
Gubberamunda
Sandstone
0.1 m rise in bore water levels
(~15km from injection)
5 m rise in bore water levels
(~5km from injection)
>50 m rise in bore water
levels, the artificial artesian
zone (~1 km from injection)
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What is managed aquifer recharge?
•
Purposeful recharge of water to aquifers for subsequent recovery or environmental
benefit.
•
Our source of water for recharge:
– Treated CSG water via Reverse Osmosis.
– Actually too clean.
•
Advantages of MAR as a re-use option:
– Reliable capacity (i.e. not dependent on rainfall/climate).
– Small physical footprint.
– Benefits all those who abstract groundwater in the region (~5km radius).
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However, increasing cost versus capacity:
– Water treatment capacity (oxygen removal and TDS <1000mg/l).
– Major cost limitation.
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Water treatment capacity scales
directly with MAR capacity
Question: How can we minimise the water treatment capacity required by MAR, whilst ensuring
we have a strategy that is not dependent on the weather?
Answer:
Incorporate a diversified water re-use solution.
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Roma asset GSP14 water forecasts
Two Water Management Concepts
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Field water production forecast
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Volume uncertainty
Water quality uncertainty
Reliability (climate) uncertainty
Expanded Centralised Capacity
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Second 10 ML/d ROP
Expansion of permanent brine solution
(100%)
4 new MAR wells
New MAR De-ox skid and MAR pipe
network*
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Decentralised water management
Decentralised Capacity
1. Blended disposal to MAR
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CS water blending (20% to achieve draft
conditions EC)
MAR IX regenerate fluid reuse (brine
reduction only)
2. Extended use of Hermitage ROP
3. Extended Use of Angry Jungle
ROP
4. Land Amended Irrigation
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Pleasant Hills (Santos Land)
Bend South (new area on Santos Land)
Land Owner Land / additional Santos
Land Irrigation
5. System Operation
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Right water to right utilisation/disposal
location
Appropriate WQ understanding
WQ licence and operating limits defined
accurately
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Why MAR and irrigation
complement each other
Robust / cost efficient water management
Volume uncertainty
– Base-load solution with cheap and nimble peak management.
Water quality uncertainty
– Can be managed (enough treatment plant capacity to manage poor quality).
Climate uncertainty
– Build irrigation areas around appraisal water infrastructure (buffer volumes) to
incorporate irrigation and achieve reliable water disposal and have MAR as
part of our solution.
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Questions?
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