Advances in modelling energy production from high enthalpy geothermal systems

1. Advances in modelling energy
production from high enthalpy
geothermal systems
John O’Sullivan
Geothermal Institute
Uniservices, University of Auckland, New Zealand

2. Outline
• The Geothermal Institute
• Geothermal projects
• Waiwera - a new reservoir simulator
• Supercritical modelling
• Shallow modelling and surface features
• Uncertainty Quantification
• Transient wellbore simulation
• An integrated workflow for a production modelling
2

3. Research
and
development
Commercial
and
consultancy services
Education
and
training
In New-Zealand and internationally
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Established 1978

4. The Geothermal Institute
• Spread across several UoA faculties and departments
• Self-funded
• The geothermal modelling team (~ 30 people):
– 8 Professors and lecturers
– 6 Researchers and developers
– 12 PhD students
– Interns
• Education:
– 1500+ graduates
– PhDs and Masters degrees
– Master of Energy
– Post-graduate diplomas
– Training courses (Kenya, Japan, Iceland, Indonesia …)
– Mentoring
• NZ Geothermal Workshop every year in November 4

5. Recent Modelling Projects
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Source: ThinkGeoEnergy
Consulting Research Student

6. • A “new”, parallel, multi-phase geothermal
reservoir simulator
• Free, open-source and officially released last
week! https://waiwera.github.io/
• Developed at the Geothermal Institute in the
University of Auckland in collaboration with GNS
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Waiwera – Reservoir Simulator

7. • Designed to replace TOUGH2 as the industry
standard geothermal simulator
• Already running complex, high-resolution models
on multi-million block grids using parallel
computing
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Waiwera – Reservoir Simulator
250C Isosurface
> 200C Model
Blocks
Steam zone

8. Supercritical modelling
• Have developed a supercritical equation-of-state
that is stable and converges well for large, full-
scale geothermal reservoir models
Whole TVZ modelled down to 8km depth
350C isosurface
Resistivity boundaries
of systems
Whole of Reykjanes Peninsula modelled in
collaboration with Reykjavik University
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9. Shallow modelling and surface
features
• Have developed robust techniques for modelling
shallow subsurface and geothermal surface features
Pohutu GeyserRotorua

10. Uncertainty Quantification
• Have developed a systematic approach for
applying formal uncertainty quantification to
full-scale reservoir models
Uncertainty in forecast steam flow rates
from a set of make-up production wells
Uncertainty in forecast temperatures in
production feedzones as a result of
reinjection 10

11. Transient wellbore simulation
• Have developed a transient simulator capable of
modelling multi-feedzone geothermal wellbores.
Idealised geothermal wellbore
11R. Tonkin (2019)

12. Integrated workflow for modelling
PyTOUGH
TIM
Geology
Geophysics GIS
Environmental
Monitoring
Pre-production
FieldData
Production
FieldData
Conceptual
Model
Geochemistry
Production
History
Model
Model
Calibration
Future
Scenarios
Natural
State
Model
Model
Calibration
TOUGH2TOUGH2 /
Waiwera
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Geothermal
Reservoir
Model

13. Conceptual model
- System in 3D
- Isotherms
- Well planning
Conceptual model
Mid Quarternary Volcanics
Upper Quarternary Volcanics
Mesozoic Basement
Terciary Volcanics
Geology,
Structures
Topography,
Geochemistry Geophysics
Pre-production
Temperature

14. Geothermal Reservoir Model
Clay cap
Faults
Automatic
model
generation
and updating
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15. Integrated Visualisations
15
Rony Nagraha

16. Kia ora

17. Wairakei Geothermal System,
New Zealand
Wairakei –
Tauhara • First field to generate electricity from
liquid-dominated geothermal
reservoir
• 300 MW
• 30 years of model development
• 60 years of production history available17

18. Wairakei - Two-Phase, Liquid
Dominated
• A two-phase region containing a mixture of steam and liquid water
overlying a deeper hot liquid layer
• Large convective flows with many surface features (geysers, hot
springs, mud pools, steaming ground)
• A permeable reservoir with production enthalpy close to 1100kJ/kg
(250oC at 1 km deep)
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19. Wairakei - 3D model forecast
Lake
Taupo city
Mt Tauhara
Steam zone
250oC
200oC
150oC
100oC
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20. • Integrated workflow:
– J.Popineau et al., An integrated Leapfrog/TOUGH2 workflow for a
production modelling. ARGeo-C7 2018
– J.O’Sullivan et al., A new geothermal workflow using Leapfrog and
TOUGH2. IIGW 2017
• Waiwera:
– J.O’Sullivan et al., Experiments with Waiwera, a new geothermal
simulator. NZGW 2017
– Croucher et al. 2015, 2016, 2017
• UQ:
– B. Gonzalez-Gutierrez et al., Accelerating the solution of geothermal
inverse problems using adjoint method in waiwera: progress report.
NZGW 2018
• Wellbore:
– Tonkin et al., Development of a transient, multi-feed geothermal
wellbore simulator. WGC 2020 (in review)
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Some Recent Papers