Overview of CO2 Production in Alaşehir Geothermal Field, Manisa,Turkey

HAKKI AYDINReservoir Engineer , Msc METU

1

Alaşehir Geothermal Field

Origin of CO2 in western Turkey geothermal field

CO2 decline Curve Analysis of Alaşehir Field

Parameters affecting CO2 decline

Effects of CO2 decline in wellbore

CO2 Emission from the field

Outline

2Zorlu Alaşehir Geothermal Field

• 50 km^2 Licensed area• 45 Mwe installed Power Plant (Doube Flash+Binary System)• 8 Production, 8 injection wells• High Enthaphy (average: 840 kj/kg) • Liquid dominated

BAŞLIK EKLE

Metin ekle

3 Noncondansable Gases

Gas Volume % in dry gas

Carbon dioxide 98.36

Hydrogen sulfide 0.003

Nitrogen 0.61

Methane 0.93

Argon 0.004

Oxygen 0.002

Hydrogen 0.093

Helium 0.00002

2%-3% of Total fluid production is NCG

98.4 % of NCG is CO2

Stable isotopes of water Meteoric WaterCarbon isotopes Marine Carbonate Sediments (No indication of Magmatic CO2

4 Origin of CO2 in western Turkey Geothermal Field

Alluvium( Quartz,mica-schist)

Kaletepe Formation ( Sandstone, Conglomerate)

Gediz Formation Salihli member (sandstone,Limestone,claystone)

Gediz Formation Hamamdere member ( sandstone,Conglomerate,claystone)

Liquid Dominated ReservoirMetamorphics (Carbonate,Marble, Calc-schist )

Geochemistry

(Yildırım and Guner, 2005, Haizlip and Haklidir, 2011, Simsek, 2003, and Aksoy et al., 2015)

Reactions between calcite and water

Metin ekle• Metin ekle

Metin ekle• Metin ekle

BAŞLIK EKLE5CO2 Lost Circulation

Higher CO2 concentration

Lower CO2concentraitonpH: 9

6 Decline Curve Analysis

Types of decline

Exponential

Hyperbolic

Harmonic

Model IdentificationWhere b,d : emprical constants to be found from production dataIf d=0 , Exponential DeclineIf d=1 , Harmonic DeclineIf 0<d<1, Hyperbolic Decline

8 Model Identification (Exponential Decline)

q (tph) vs Q(ton) log q(tph) vs t(hr)

9 Model Identification (Exponetial Decline)

log q(tph) vs log Dt (hr) log q(tph) vs Q (ton)

10Parameters affecting Decline Rate

Flow rate

- Large flow rates accelerate CO2 production decline rate- Fast production less time for formation dissolution

Reservoir Pressure - Pressure maintenance (injection related) accelerate decline- Pressure drop (high Q) decrease formation solubility- Pressure maintenance (natural recharge) contribute formation solubility Permeability-Thickness

- Higher fracture surface area (contact area), higher formation solubility

11Well Alkan-5 & Alkan-3 location

Close to injection site

Faraway to injection site

12Well Alkan-5 Reservoir Pressure Drop

Pressure drop6 bar

13 Alkan-5 C02 decline curve

August 2015

Septem

ber 2015

October

2015

November

2015

March 2016

April 2016

May.16

June.16

July.16

August 2016

Septem

ber 2016

October

20160.0

0.5

1.0

1.5

2.0

2.5

Alkan5

Alkan5

Date

CO2

flow

rate

, tph

- Reservoir pressure drop 6 Bar- Temperature is the same- CO2 decline 2.2 tph to 0.5 tph 77.2% CO2 decline

14 Well Alkan-3

15 Alkan-3 C02 decline curve

August 2015

September 2015

October 2015

November 2015

March 2016

April 2016 May.16 June.16 July.16 August 2016

September 2016

October 2016

01234567

Alkan3

Alkan3

Date

CO2

Flow

rate

, tph

- Reservoir pressure drop 12 Bar- Temperature is the same- CO2 decline 5.7 tph to 5 tph 12 % CO2 decline

16 Alkan-3 vs Alkan-5 Cl Comparison

16 Alkan-3 vs Alkan-5 Decline rate Comparison

Alkan-3

• Kh (thickness-permeability) larger than Alkan-5• Flowrate is 2.5 times larger than Alkan-5• Pressure Drop : 12 Bar• Cl concentration is lower than Alkan-5• 12% decline in CO2 production

Alkan-5

• Lower kh & flowrate compare to Alkan-3• Pressure drop 6 bar• Higher Cl concentration compare to Alkan-3• 77 % decline in CO2 production

Note :*İnjection related water( base , ph:9) dominate decline rate in CO2 production.*Larger kH means higher contact area for dissolution.

17Wellbore simulation

Input:Only C02 contents are different

Output:

CO2 0.5% C02 2.5%Pwhf,bar 15.28 20.7Gas Breakout Depth,m 147 614

18Carbondioxide advantages and disadvantages in wellbore

Advantage:- Higher wellhead pressure- Contribute total steam rateDisadvantage:- Deeper flashing point (mechanical problems, cost )- scaling problems

Fukuoka 812-8581 Japan

19Alaşehir CO2 Emission

Binary works

Adding a new well

20 CO2 emission from various types of power plants

WNA report 2011 & Hunt, 2000.

360 g/kWh

BAŞLIK

21

Origin of CO2 in Alaşehir geothermal field: meteoric water and formation dissolution

Exponential Decline Curve for CO2 decline rate

Parameters affecting CO2 decline rate :

Reinjection water dominate wells’ CO2 decline rate

Advantages of higher CO2 % in wellbore: High total steam rate, high Wellhead Pressure

Disadvantage of higher CO2% in wellbore: Flashing point is deeper (long tubing installation) high

mechanical problems risk

Gas emission in Alaşehir Geothermal Field is on the average of geothermal power plants

Although Geothermal power plants release CO2 to atmosphere they are still much cleaner than

fossil fuels

Conclusion and Comm

ents