GNS Geothermal Workshop by JOGMEC

温泉との共生のための研究
For co-existence of geothermalbusiness and local hot spring business
安川香澄
Kasumi Yasukawa
産総研 再生可能エネルギー研究センター
Renewable Energy Research Center,
National Institute of Advanced Industrial Science and Technology (AIST)

Topics 本日の内容• “Harmonious geothermal reservoir management
system with hot springs”
温泉共生型地熱貯留層管理システム• “Advanced Software for harmonious reservoir
management system with hot springs”
温泉共生貯留層管理システム用アドバンスド・ソフトウェア• Related current researches by AIST GeothermalTeam (hot spring monitoring sensor, etc.)
産総研地熱チームによる現行の関連研究（温泉モニタ用センサー、ほか）
2Harmonious geothermal reservoir management system with hot springs

Background of the study• For developments of new GPPs, agreement with local society is essential.
Interference to nearby hydraulic system should be avoided (in Japan,special care for commercialized hot springs is needed).
• Logically there should not be a problem if;
 Natural heat & fluid recharges and utilization are well balanced,or A caprock exists between hot spring aquifer(s) and a geothermal
reservoir.

• A three-year research project “Development of an advanced
geothermal reservoir management system for harmonious utilization
with hot spring resources”(2010-2012) was conducted to indicate away to exploit geothermal energy without negative impacts on nearby hotsprings, sponsored by Ministry of Environment.
3

Development of an advanced geothermal reservoir management system

Possible relation between geothermal
reservoir and hot spring aquifer
Hot spring
Aquifer

同一型

Geothermal
Reservoir

熱水滲出型

蒸気滲出型

熱伝導型

Possibility and large
type of influence F.R., T

mediumF.R., T, Che

small
Che, Tvery small
T

独立型

none-T: Temperature, F.R.: Flow Rate, Che: Chemical component
Based on geothermal system modeling, type of relation and possible influence(s)will be identified. Monitoring parameters will be chosen based on the type.

Harmonious geothermal reservoir management system with hot springs

Flow chart of ”Harmonious Geothermal Reservoir
Management System with Hot Springs”
Basic technicalcomponents:•Geothermal
modeling•Numericalsimulation•Monitoring
are the same as normal
geothermal exploration.
Special feature is that allmodeling, numericalsimulation and monitoring
include hot spring well(s)and hot spring aquifer(s).

Harmonious geothermal reservoir management system with hot springs

Two Model Fields of the project
Hachijojima Island• Hachijojima GPP (3MW) has
been in operation since1999.
• Case study with full data set
from GPP
Minami-Izu• No GPP, but many hotspring wells exist in the area.
(No development plan yet)
• Case study with limited data

Harmonious geothermal reservoir management system with hot springs

Studies at Hachijojima• Volcanic island
N

Observation welldrilled in thisproject

Hachijojima GPP
3MW since 1999

Hot springmonitoring wells
0 12 3 4 5 km

• Operational data of the GPPare available.
• Detailed numerical simulation
had been done for power
production.
• Additional geological,geochemical andgeophysical study has been
done to extend numericalmodel to cover hot spring
aquifers.

Harmonious geothermal reservoir management system with hot springs

Studies at Hachijojima
Production well

Production well

Deep observation well

3D Resistivity model of Hachijojima area as a result of 2D
inversion of MT and AMT data
• Shallow part is re-constructed with higher resolution.
• Low resistivity zone is corresponding to caprock.

Development of an advanced geothermal reservoir management system

Studies at Hachijojima
Hachijojima 3D reservoir
model was:
• Extended to cover hot
spring aquifers, and• Re-gridded to re-construct
shallow aquifer level.

Numerical simulation

Harmonious geothermal reservoir management system with hot springs

Studies at Hachijojima
Simulation result shows• Even 10 times bigger
production than real
production does not affect onshallow aquifer.
It is consistent with
Geothermal Modeling
result, suggesting thissystem is Type 5.
(independent systems)

Numerical simulation

Red: temperature
blue: pressure,green: salinityyellow: steam
saturation

Natural state model

10 years after production(real production rate)

5 years after production(10 times bigger than realproduction rate)

Development of an advanced geothermal reservoir management system

Studies at Minami-Izu•Several hot spring wells (150–200 m deep, 100oC) exist in
the east of a fault.
•No information is available for deeper part.
•A test production well (695m) and an injection well (200m)
are drilled in this project to investigate connection between
deeper and shallower parts.
0Location of wells in Minami-Izu

5 km•No hot-springmonitoring has been
done in this area.
•So we monitored a
hot spring well toidentify its naturalfluctuation intemperature, waterlevel and electric
conductivity.

Development of an advanced geothermal reservoir management system

Studies at Minami-Izu

K-3

K-11

K-13

Production-injection test and tracer test in Minami-Izu

K-6

Harmonious geothermal reservoir management system with hot springs

Studies at Minami-Izu
Production well
Tracer injection
9/16 9:00am
Tracer arrival
9/22 - 23?

K-11
Tracer injection
9/16 9:00am
Tracer arrival
9/27 10:00 amTracer recoveries
Tracer from shallow injection well reaches to deep production wellearlier than shallow K-11, suggesting vertical hydraulic connection.

Harmonious geothermal reservoir management system with hot springs

Studies at Minami-Izu

3D Resistivity model of Minami-Izu area as result of 2D inversion ofMT and AMT data
•Shallow part is re-constructed with higher resolution.
•Low resistivity zone is corresponding to reservoir.
•No caprock exists between hot spring aquifer and deeper part =suggesting verticalhydraulic connection.

Harmonious geothermal reservoir management system with hot springs

Studies at Minami-Izu
Another result• The hot-spring-monitoring
result shows fluctuation inwater level and temperature
due to pumping, precipitation,seasonal change, etc.
• Importance of long termmonitoring should beemphasized to detect impactof any external causes.

Tracer test, resistivity survey, etc. suggest strong hydraulicconnection of shallower and deeper parts.
•This system is Type 1 or 2 at least to the depth of 700 m.
•In case of geothermal development, careful monitoring of discharge
and recharge balance is needed.

Harmonious geothermal reservoir management system with hot springs

System support software(proto-type software)

Function 1: タイプ判別
Simplified type analysis
by hot spring chemistry
Function 2: 干渉の評価
Interference evaluation
by time series analysis*Both Functions use
hot spring data only
(no geothermal data).

Some improvements are needed for practical use. -> It’ll be explained in the next section,“Advanced Software for harmonious reservoir management system with hot springs.

Harmonious geothermal reservoir management system with hot springs

Summary of “Harmonious geothermal reservoirmanagement system with hot springs”“温泉共生型地熱貯留層管理システム”のまとめ•

An integrated geothermal reservoir operation system (scenario) for
adequately controlled utilization was developed to conduct geothermal
development without interference to nearby hot springs.

•The system consists of three parts: Geothermal modeling, Numericalsimulation and Monitoring.

•

The system was applied to two model fields. The results showed that
the Minami-Izu field is Type 1 or 2 (identical system or water supply
from deep reservoir) while the Hachijojima field is Type 5(independent type).

•Importance of long term hot-spring-monitoring is emphasized to detectimpact of external causes including geothermal production.

•A proto-type system support software, which helps “type analysis” and“time series analysis” is developed, which should be improved.

 Acknowledge: this project was sponsored by Ministry of Environment.

Advanced software for harmonious reservoir
management system with hot springs
温泉共生貯留層管理システム用アドバンスド・ソフトウェア

1. Introduction
2. Function 1 : Type analysis
 Type of relationship between hot spring aquiferand geothermal reservoir

3. Function 2 : Time series analysis
 Correlation analysis with any other data Student T-test

4. Discussion and Summary18

Advanced Software for harmonious reservoir management system

Introduction: Concept of the Advanced Software
for harmonious reservoir management system with hot springs•

For management of hot spring system, monitoring of 1) flow rate/water level,2) temperature, and/or 3) chemical component is needed.

•Among many causes of hot spring fluctuation in above three items, internalcause (ex., pumping of hot spring itself, interference of hot spring wells) aremost likely causes. Geothermal development is one of external causes.

•Interference of geothermal development on hot springs; is controlled by hydrological shielding ability of geological formation
between them and balance of fluid and heat recharge and extraction.
 should be assessed in duration of few months to few years.

•Hydrological shielding ability may be identified by 3D positioning of hotspring and geothermal reservoir and formation mechanism of hot spring.

•If the shielding ability is identified to be insufficient, interference should be
predicted by time series analysis of monitoring data.
19

Advanced Software for harmonious reservoir management system

Introduction: Flow chart of the Advanced Softwarefor harmonious reservoir management system with hot springs

Function 1
Type analysis(interferenceprediction)

Function 2
Time series
analysisof interference

MakingGraph &Map
Advise bySpecialist

Possibility ofinterference*Basic functions need hotspring data only → local
communities may use thissoftware to protect their own
hot springs.

Advise bySpecialist

Data input“Type”
identification
Show “Type”
Interference
analysis
unclearHot spring data
- location, temperature, geochemistry- distance from geothermal reservoir
Type of relation between hot springand geothermal reservoir- Based on Type and distanceNo interferenceQuantitative
analysis?
yesnoTime series
analysis- Correlation function- Student’s T-test

Show result- “No interference” or- Possible interference and time

Show result-“No interference”

Advanced Software for harmonious reservoir management system

Function 1 Type analysis (interference prediction)
Proto-type software Type is roughly identified by
the characteristic of hot spring.
Threshold shown in GRSJ (2010),
based on 4,536 hot spring data inGSJ (2005)

Type
Type 1
Type 2Type 3
Type 4

Relation: hot spring &geothermal reservoir

Identical system
Water supply
from deep reservoir

Steam supply
from deep reservoir

Heat conduction

Type 5 Independent system

Possibility ofInterference

Characteristics ofhot spring

Required monitoring(Possible interference)High

Cl- /total anion >80%
Temperature >53oC

Flow rate
Flow rate

Medium

Cl- type
Temperature >53oC

Low

SO4- type
Temperature >53oC

Chemical Component

Very lowNone(Temperature)(Temperature)(Electric conductivity)(Temperature)

Total ions < 1000 mg/L
(Temperature)
Temperature >25oC
No particular type

No21

Advanced Software for harmonious reservoir management system

Function 1 Type analysis (interference prediction)

Proto-type software: Flow chart of Function 1
Simplified type analysis by hot spring chemistry
Hot spring Chemical
Total
temperature
type concentration(mg/L)

Chargebalance

NGClOK≧53℃

Data
variety
Detailed
data

Detailed
analysis

25℃≦
＜53℃

Simpleanalysis

No data＜ 1000Type 3:steam supply

≧1000

SO4
others＜25℃

Nojudgment

SO4othersLimiteddata

Type 1: identical, orType 2: water supply＜ 1000Type 4:heat conduction≧1000

OthersType 5: independent

Problem: wrong judgment for hot springs with “dominant
CO2“ or with “volcanic gas.

Advanced Software for harmonious reservoir management system

Function 1 Type analysis (interference prediction)

Improvements in the advanced software• Two types are newly added for a better type analysis.
Hot spring

CO2Geothermal
reservoir

VolcanicgasMagma

CO2 supply (from rock)• HCO3- is so dominant that ratio of Cland SO4- cannot be evaluated.
• Interference Type is not predictable.
(It could by any of Type 1-5)

Volcanic gas supply• Cl- > SO4-, but not Type 1 or 2.
• Identified by low pH.
• No interference (Type 5).
23Advanced Software for harmonious reservoir management systemFunction 1 Type analysis (interference prediction)

Advancedsoftware

Type

Type 1
Type 2Type 3

Relation: hot spring &geothermal reservoir

Identical system
Water supply
from deep reservoir

Steam supply
from deep reservoir

CO2 supply
Type 4Heat conduction

Possibility ofInterference

Characteristics ofhot spring

Required monitoring(Possible interference)High

Cl- /total anion >80%
Temperature >90oC

Flow rate

Flow rate

Medium

Cl- type
Temperature >60oC
SO4- typeChemical Component

Low

unpredictable HCO3- type
Very low(Temperature)(Temperature)(Electric conductivity)(Temperature)All

Total ions < 1000 mg/L(Temperature)
Temperature >25oC

Type 5 Independent systemNone

No particular typeNo

Volcanic gas supply(independent)

None

pH<3 and Cl->SO4-NoAdvanced Software for harmonious reservoir management system

Function 1 Type analysis (interference prediction)

Advanced Software: Flow chart of Function 1
Simplified type analysis by hot spring chemistry
Steam onlyor naturalfumarole

Hot spring
temperature

Chemical type

90℃≦T

Cl- type (≦80%)

yes nopH<3 andCl->SO4-60℃≦TT＜90℃

yes noAll anion data(Cl-, SO4-,HCO3-) exist?

noVolcanicgas supply
No judgment(poor data)

anion: 80%≦Cl-SO4- typeType 2:water supply

others

CO2 supply

Cl- typeSO4- typeyes25℃≦TT＜60℃

T＜25℃

othersTotalconcentration(mg/L)

SO4- type≧1000

HCO3- type<1000

others<1000

HCO3- type≧1000

othersNo T data

Type 1: identical

Type 3:steam supply

Type 4: Heatconduction

Type 5:
Independent25

Advanced Software for harmonious reservoir management system

Function 2 Time series analysis of interferenceTime series analysis• Correlation function with any time series data,such as meteoric or geothermal reservoir data (ifavailable) can be calculated.
• Influence of geothermal development or any
other cause can by analyzed by Student’s T-test,
by calculating the change of fluctuation
amplitude after a specific time line.
Improvements in the advanced software is done mainly for the userinterface of data input.
26

Advanced Software for harmonious reservoir management system

Function 2 Time series analysis of interference

Cl concentration
Ｃｌ濃度 ( mg/l )(mg/L)

Student’s T-test- concentration of a hot spring water
発電の影響がない場合のCl濃度変化（仮想データ）
Cl(imaginary data)
発電所運転前発電所運転後206
204202200198
196194

Time series analysis

No interference

01020304050

Student's T-test

60

月
発電の影響がある場合のCl濃度変化（仮想データ）
monthsClＣｌ濃度concentration( mg/l )Opening of発電所運転前
apower plant

発電所運転後205

Interference

200190185102030月
months4050

judgment

Upper
figure-0.365

Within natural
perturbation

Lower
figure6.202

Out of natural
perturbation

If within natural perturbation,-2.013≦ ｔ ≦ 2.013.

1950tvalue

60

Lower figure is considered tohave interference.

Advanced Software for harmonious reservoir management system

Discussion: cautions for using the software• Flow rate (water level) of a hot spring may mislead the result.
Total flow rate of hot springs from the same aquifer should bemonitored.
• If a trend change is observed in a time-series of hot spring data,
mutual interaction of hot springs should be investigated first.
• Then if mutual interaction cannot explain the observed data,
external causes including geothermal operation should beinvestigated.
• Possibility of interaction by geothermal reservoir operation may
generally be indicated by Cl- ion concentration.
• If a sudden pressure drop or continuous pressure decline of thegeothermal reservoir is observed, monitoring of nearby hot springshould be carefully done.
28Advanced Software for harmonious reservoir management system

Summary of “Advanced Software”• The newly developed “Advanced Software” analyzes the possibility
and type of interference of geothermal development onto near-by
hot springs based on geochemistry of the hot springs only.
• The major improvement from the proto-type software isconsideration of volcanic-gas-supply type and CO2-supply type.
• Time series analysis of hot spring data can also be done to detect
the trend change in the data series.
• Special feature of the software is that basic functions require hotspring data only so that local communities may use it to protect
their own hot springs.
• Authors hope the software encourages geothermal development by
supporting understanding of local community.

29

Related current researches by AIST GeothermalTeam (hot spring monitoring sensor, etc.)
産総研地熱チームによる現行の関連研究（温泉モニタ用センサー、ほか）• Earth-thermal simulator• Development of a sensor for hot springmonitoring• Simulated hot spring water generator

30

Related current researches by AIST Geothermal Team

Development of Earth-thermal simulator （地球熱シミュレータの開発）
By numerically simulating various phenomenon which occur during geothermal
development, sustainable and optimum development scenario, andpossible interference onto nearby hot springs may be clarified.
It would help to find a development scenario with less impact to environment.

Earth-thermal simulator
For modeling of the whole hydro-geological system
GSHP

Aquifer

Hot spring

RiskonHot communication
springsurrounding environment

Optimum development
including HDR to GSHP

Low temp.
Resources
HDR resources

GeothermalReservoir

Related current researches by AIST Geothermal Team

Searching for Optimal and Sustainable Geothermal Development
Methods with Less Environmental Impact, …
Development of a sensor for hotspring monitoring（温泉モニタリングセンサの開発）
sponsored by NEDO

• Flow rate
• Temperature• Electric conductivity
 Target is a reasonable and compactsystem.
 A proto-type sensor is under test ata real hot spring (Obama, Nagasaki).

Simulated hot spring water generator（温泉システム模擬装置）
Hot spring water of various spring qualities
can be simulated.
It may be used for the evaluation of a hotspring monitoring sensor, experimentationof a hot spring power generation, etc.