Overview of Indonesian Geothermal System

The Resources Beyond High Enthalpy Magmatic/Volcanic Systems

4/3/2017 1

By

Dr.Eng. Suryantini

ITB

Outline

• Current Condition of Indonesian Geothermal

Resources and its Systems

• Geology of Geothermal Systems

• Resources Beyond High Enthalpy

Volcanic/Magmatic Associated Geothermal

Systems

• Concluding Remark - The Future of Exploration,

Utilization Challenges and Opportunities

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Current Condition of Indonesian Geothermal Resources and its Systems

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Current Condition of Indonesian Geothermal Resources

330 Prospects 69 (<21%) Geothermal Working Areas (GWA)

11 Production GWA (<16% from total GWA or 3% from total prospects)

29,452 MW Potential 2,288 Mwe (7.8%) Proven Reserve

1,438.5 Mwe (63% from Proven or <5% from total potential) Production

GWA Producer GWA Un-Producer GWA in bidding

Sources : MEMR, 2016

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Indonesian Geothermal vs Present Day Volcanic Arc

Most of the Prospects are associated with volcanic arc

Sources : MEMR, 2016

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Tectonic that control volcanoes and geothermal occurrences

• Most geothermal occurrences is associated with volcanic or magmatic heat sources

• Other is non-volcanic or amagmatic heat source extinct magmatic at old subduction

zone, tectonic extensional domain, or Intra-cratonic basin, or conductive system4/3/2017 6

Current Condition of Indonesian Geothermal Resources and its Systems

1) Imbalance between resource availability and development Inefficient geothermal energy utilization

2) Geosciences perspective on this condition i.e.

a. The prospect is less attractive due to i.e. low potential, unsuitable for world class developer

b. Lack of understanding about geothermal system improper project plan suspend of the project

c. Misunderstanding of reservoir permeability as drilling target drilling failure suspend of the project

3) Most of geothermal systems that produce electricity is associated with volcanic or magmatic heat source with prominent surface manifestation

what if the manifestation is very little and less or inactive?

What if the volcanism is absence?

4) Low-Medium Enthalpy has not been explored or studied further4/3/2017

7

Geology of Geothermal Systems

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• “A geothermal system is any localized geologic setting where portions of the Earth׳s thermal energy may be extracted from natural or artificially induced circulating fluids transported to a point of use.” (Moeck, 2014)

• Geologic setting has a fundamental influence on the potential temperature, on the fluid composition, the reservoir characteristics and mode of heat transfer (convective or conductive)

• Failure in understanding this geologic setting (and all the supporting geologic elements that determine the setting) may cause many technical and financial problems that eventually leads to projects suspended or terminated.

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Geothermal Plays – IGA classification

• “Geothermal Play” is adopted from Petroleum

• Translated to geothermal systems, a geothermal play type might be defined as a geological setting that includes

a heat source,

heat migration pathway,

heat/fluid storage capacity,

and the potential for economic recovery of the heat

(IGA, 2014)

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Indonesian geothermal systems have all possible play types

Which play type is your geothermal system?

(IGA, 2014)

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Magmatic Play Type – Active or Recent Magma Intrusion

• A familiar model for Indonesian Geothermal System.

• Recent (but not active) intrusions underneath or in the vicinity of volcanoes heat sources, with intensive surface manifestation.

• An active magma chamber does not always produce volcanism !

Age of Volcanism

- Active magmatism: volcanism <500 yrs

- Recent magmatism: volcanism 500-50,000 yrs

- Inactive or extinct magmatism: volcanism >50,000 yrs

De

pth

(k

m)

(IGA, 2014)

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Active or recent magmatic play type with intrusive magma chamber.

• Influenced by active faulting, deep rooted magmas can intrude beneath flat terrain with no volcanism.

• Manifestation might be occur

• An upflow and outflow zone might be occur provided the topography of volcano support this

Magma chamberPluton

De

pth

(k

m)

(IGA, 2014)

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• Examples are Lardarelo and The Geyser

• Typically located along continent-continent convergent or transform margins with recent magmatism

• Surrounding mountain ranges provide high recharge rates of meteoric water

• Manifestation might be occur

(IGA, 2014)Quartenary granitic pluton

Metasediments

In Lardarelo:

Pliocent Epoch

- At 1.3-3.8 Ma.

- Extensional event

-Granite intrusion

-Low-angle normal

faults recharge

Pleistocene Epoch

-At 0.2-0.3 Ma

-magmatic event

primary heat source

Extinct magmatic play types controlled by late Cenozoic to Quaternary plutons or batholiths without associated volcanism.

De

pth

(k

m)

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Extinct magmatic play types controlled by late Cenozoic to Quaternary plutons or batholiths with associated volcanism.

• Previous play type can coexist with active or recent volcanism

• Hence two systems might be coexist

• Which one is your systems ?4/3/2017 15

(IGA, 2014)

Extensional domain play type, with possible fault controlled fluid flow paths.

• The elevated mantle principal heat source high thermal gradient

• deep faults or permeable formations fluid circulation path

• Non-magmatic, may be “fault zone controlled” or “fault-leakage controlled” at the system scale.

• Segmented faults are more favorable for geothermal systems than large faults with large offsets

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(IGA, 2014)

Conduction-Dominated Play Types

• Passive geothermal systems absence of fast convective or fluids dynamics

• Passive tectonic plate settings no significant recent tectonism or magmatism.

• Favorable geologic setting : extensional, divergent margins and grabens, or lithospheric subsidence basins, foreland basins within orogenic belts, and crystalline basement underlying thermally insulating sediments,

• Classified based on natural porosity–permeability ratio within the potential reservoir rock, and the absence or presence of producible natural reservoir fluids.

Intracratonic Basin Type,

Orogenic Belt Type, and

Basement Type

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Conduction-Dominated Play Types

Intracratonic Basin Type

Orogenic Belt Type4/3/2017 18

Resources Beyond High Enthalpy Volcanic/Magmatic Associated Geothermal Systems

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Key point of volcanic or magmatic geothermal system

1. Age of volcanism determine the maturity of volcanism radiometric age dating ?

2. An active magma chamber does not always produce volcanism geophysics ?

3. Intrusion not beneath the system but in the vicinity, what if composite volcano? Or caldera? geophysics ?

4. Most of geothermal exploration is guided by the occurrence of manifestation, in absence of surface manifestation or when the upflow-outflow zone is subtle Exploration concept play significant roles

5. An insight into the whole model or concept is necessary4/3/2017 20

Tangkuban PerahuIs Ciater part of Tangkuban Perahu System?

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Patuha

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Wayang Windu, Darajat and KamojangIs there any geothermal system between Darajat-Kamojang?Is there any potential at Malabar north of Wayang Windu?

WayangWindu

Kamojang

Darajat4/3/2017 23

Silangkitang - Sarula

Silangkitang

Namora

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Muaralaboh4/3/2017 25

Integrating regional data from petroleum exploration

Would it be possible to find Extensional domain play type4/3/2017 26

Integrating with regional data from petroleum exploration : Lesson Learned

Geothermal System in Sumatra is controlled by volcanism due to subduction and mega strike slip Great Sumatran Fault which lies on continental granitic basement. It is a unique complexes system.

Understanding the tectonic, geology and play type is crucial for discovery of geothermal system.

Try to elaborate all geological data even from petroleum exploration or other survey

Discuss the data, share the knowledge

Blind system may be discovered

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Discuss the data, share the knowledge to get the complete picture

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What about geothermal system in Sulawesi and others in eastern Indonesia?

Hall and Wilson, 20004/3/2017 29

Geothermal Potential at the Sedimentary Basin in Sumatera

Utilization of abandoned petroleum well (~700 abandoned well in Sumatera only)

Regional Heat flow map is necessary

There are >60 Tertiary Sedimentary Basins in Indonesia

Conduction dominated in sedimentary basin

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Conduction Dominated – Orogenic Belt Type

1. Sunda Orogeny : Java Southern Mountain Ranges – Sumatera Barisan Mountain Ranges

2. Banda Orogeny : Sulawesi Mountain Ranges

3. Melanesia Orogeny : West Papua – Papua New Guinea Mountain Ranges

4. Talaud Orogeny : Talaud – Tifore ridge

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The potential of conductive dominated – in orogenic belts

• Sunda Orogeny

• Banda Orogeny

• Melanesia Orogeny

• Talaud Orogeny4/3/2017 32

Concuding remark:

The Future Exploration and Utilization Challenges and Opportunities

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• Integrating tectonic and regional geology to better understand the geothermal system both for volcanic – magmatic or non volcanic

• Collecting radiometric dating as many as possible

• Start to carry out exploration program in conduction dominated

• Think out of the box…

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……. Thank You …..

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