calpine corporation nw geysers enhanced geothermal system

Calpine Corporation

NW Geysers

Enhanced Geothermal System

Demonstration Project

November 2, 2012

Community Update

Calpine Geysers Visitor Center

Middletown, CA

Calpine

Northwest Geysers Enhanced Geothermal System Demonstration

Accomplishments, Results and Progress

• Prati State 31 and Prati 32 were recompleted as a

production-injection well pair in September 2011 (respectively).

• Injection into Prati 32 began on October 6, 2011 and has been

continuously monitored.

• Continuous injection of water at rates of 400, 700 and 1000

gallons per minute into 750OF rock at a depth of 11,000 feet.

• A microseismicity “cloud” began to form almost immediately

with the Prati 32 water injection.

• An Enhanced Geothermal System has been created in hot dry rock.

The evidence for this comes from the analysis of:

Microseismicity data

Isotope data

Temperature data

Pressure data

Prati State 31 flow response

• A connection has been established between the deep, hot-dry rock

reservoir and the overlying normal temperature reservoir.

There are approximately 1100 undeveloped

acres in the vicinity of the EGS

Demonstration Area which are

underlain by a high-temperature, hot

dry rock reservoir.

Aidlin 1

View From West The undeveloped EGS Demonstration Area

is 7 to 9 miles from the nearest

sensitive communities.

Future Directions – Additional EGS

Development Area

EGS

Demonstration

Area

Injection:

Prati 32

Production:

Prati State 31

Microfractures Within

High Temperature Reservoir

260o C / 500o F

400o C / 750o F 11,143’

10,134’

SW NE

Scientific/Technical

Approach

Final Bit from Prati 32 (11,134’)

after 100’ of drilling where

Temperatures are 750 oF

Average Bit Condition after 300’

of drilling at the Geysers where

temperatures are 450 oF

Prati 32 Deepening

Calpine

Northwest Geysers Enhanced Geothermal System Demonstration

Water “Injection” Under Vacuum

Control Valve

Water Flow

Top of High

Temperature

Reservoir

Top of Standing

Water Column

Why Vacuum Conditions?

Injection of cool water into the hot steam reservoir

Steam condenses with a significant volume reduction

Results in vacuum conditions

Injected water “drawn” into reservoir

The NW Geysers EGS Demonstration Project

is “injecting” water under vacuum conditions

(as with all water injection at The Geysers)

Micro-fracture development relies primarily on thermal effects,

not pressure effects (as used in hydrofracturing)

Prati 32 Well Diagram Not to Scale

To Production

Well(s)

200

150

100

50

0

250

Day

s S

ince

In

ject

ion

Sta

rt

300

Prati 32 Injection Interval 7800’ to 11143’

Prati State 31 Production Interval

6900’ to 10000’

M 2.67

M 2.55

M 2.54

M 2.69

M 2.87

M 2.68

M 2.56

Calpine NW Geysers EGS Demonstration

Seismicity Analysis: 01 September 2011 to 19 September 2012 LBNL database events with ErH (horizontal error) and ErZ (vertical error) less than 1 km



Seis

mic

Eve

nt

Mag

nit

ud

e

2.5

2.0

1.5

1.0

0.5

0

3.0

200

150

100

50

0

250

Day

s S

ince

In

ject

ion

Sta

rt

Prati 32 Injection Interval 7800’ to 11143’

Prati State 31 Production Interval

6900’ to 10000’

300





Instrument Failure (?)

11

Negligible Strong Motion Instrument Responses at Anderson Springs and Cobb From Maximum Seismic Event (M 2.87)

Magnitude 2.87 Event

31 May 2012, 05:31:26 UTC

Anderson Springs:

Geometric Mean (Horizontal Components):

1.53 cm/sec2 = 0.16% of gravitational acceleration

Modified Mercalli Intensity: I

Not Felt; No Potential Damage

Cobb:

Geometric Mean (Horizontal Components):

1.38 cm/sec2 = 0.14% of gravitational acceleration

Modified Mercalli Intensity: I

Not Felt; No Potential Damage

20120531_053126_COB-03432_EF081 COB 05/31/2012/ 05:31:26.000

HNE 1.484894 0.019180 0.590780 0.054566 0.008896 HNN 1.281621 0.021821 1.063913 0.045667 0.008398 HNZ 0.818167 0.010188 0.395494 0.036799 0.004547

20120531_053129_ADSP-03433_FF1239 ADSP 05/31/2012/ 05:31:26.000

HNE 1.718394 0.022286 0.600226 0.034296 0.008010 HNN 1.366358 0.019826 0.484243 0.029602 0.010503 HNZ 0.998494 0.011479 0.185820 0.014799 0.004931


Seismicity Analysis: 01 September 2011 to 19 September 2012

Research Collaboration with European GEISER Project Coordinated with Dr. Roland Gritto; Array Information Technology

At The Geysers:

• 32 stations installed in early 2012:

• 25 within field boundary

• 7 beyond field boundary

o Continuous monitoring

o Broadband

o Within and beyond geothermal field

The Geysers

Field Outline

Most are co-located:

LBNL Stations (24)

USGS Stations (4)

Strong Motion Stations (1)

Improve understanding of:

structural features

seismic energy attenuation

seismic velocities (Vp and Vs)

velocity change with reservoir fluid variations

This seismic monitoring network contributes to worldwide GEISER consortium goals

Seismic Monitoring Advisory Committee Meeting

1 October 2011 to 31 March 2012

Additional Seismic Monitoring and Research

Seismic Monitoring Advisory Committee Meeting

1 October 2011 to 31 March 2012

Additional Seismic Monitoring and Research

Research Collaboration with European GEISER Project*

Coordinated through GFZ Potsdam (Germany)

Goal:

Address challenges to geothermal energy

Main topics:

Mendocino County Line GEISER Seismic Monitoring Station

* GEISER Partners: GFZ Potsdam, BRGM, ISOR, TNO, ETHZ, STATOIL, GEOWATT, NORSAR, ARMINES, EOST, KNMI, AMRA, INGV

1. World-wide acquisition and analysis of induced seismicity data

2. Understanding induced seismicity the geomechanics and processes

3. Consequences of induced seismicity

4. Strategies for the mitigation of induced seismicity

Action Packer with

Digitizer and Battery

Solar Panel on

Triangular Frame

Triaxial Broadband Seismometer

in Sealed Container

GÜRALP: 60 second to 50Hz

or

Trillium: 120 second to 100 Hz

Trillium triaxial

seismometer

http://www.geiser-fp7.eu/GEISERForBeginners/Pages/Partners.aspx

14

?

?

Prati 32

345 psig

PS 31

340 psig

Prati 25

340 psig

Prati 38

285 psig

Prati 9

300 psig

Northwest Geysers EGS Demonstration Stimulation (Injection started: 10/06/2011 10:00 AM)

Abril 2

182 psig

WHS 56

190 psig

WHS 36

345 psig

WHS 34

365 psig

WHS 71

345 psig

Calpine NW Geysers EGS Demonstration Geochemical Analysis

Prati 32 Injection and Prati State 31 Pressure Response

18

Inje

cti

on

Ra

tea

tP

rati

32

[gp

m]

We

llH

ea

dP

res

su

re[p

sig

]

Pra

ti2

5F

low

Ra

te[K

PH

]

20

11

-10

-08

20

11

-10

-22

20

11

-11

-05

20

11

-11

-19

20

11

-12

-03

20

11

-12

-17

20

11

-12

-31

20

12

-01

-14

20

12

-01

-28

20

12

-02

-11

20

12

-02

-25

20

12

-03

-10

20

12

-03

-24

20

12

-04

-07

20

12

-04

-21

20

12

-05

-05

20

12

-05

-19

20

12

-06

-02

20

12

-06

-16

20

12

-06

-30

20

12

-07

-14

20

12

-07

-28

20

12

-08

-11

20

12

-08

-25

20

12

-09

-08

20

12

-09

-22

20

12

-10

-06

20

12

-10

-20

0

200

400

600

800

1000

1200

1400

1600

1800

320

340

360

380

400

420

440

460

480

500

50

60

70

80

90

100

110

120

130

140Prati 32 Injection

Prati State 31 WHP

Prati 25 WHP

P25 Flow

PS 31 Data Logger WHP

P32 WHP

Injectivity Test

(11/15/11)

Water Depth [rate]

7490 ft [606 gpm]

7454 ft [871 gpm]

7450 ft [1218 gpm]

Injectivity Test

(10/17/11)

Water Depth [rate]

7770 ft [215 gpm]

7356 ft [600 gpm]

7479 ft [1195 gpm]

Injectivity Test(3/6/12)

Water Depth [rate]7192 ft [200 gpm]7103 ft [533 gpm]7094 ft [800 gpm]

7071 ft [1180 gpm]


Water Depth [rate]7295 ft [228 gpm]7259 ft [522 gpm]7170 ft [790 gpm]

7127 ft [1180 gpm]


Water Depth [rate]7486 ft [217 gpm]7338 ft [602 gpm]

7209 ft [1265 gpm]

The injection of SRGRP wastewater into Prati 32 resulted in wellhead pressures Increasing in Prati State 31 from about 320 psi before injection to 460 psi after five months of injection. Consequently, the steam flow increased in Prati State 31

• Flow rate of PS-31 increased from 55,000 lb/hr prior to the October 2011 stimulation, to 93,000 lb/hr when tested in January 2012.

• Total NCG decreased more than 90%

following the injection of water at P-32.

• About 5 MW equivalent of new

injection-derived steam from SRGRP wastewater which is produced from PS-31 and P-25 may result if the proposed Wild Horse Power Plant is constructed near the EGS demonstration.

WELL KPH

(klbs/hr)

WHP

(psig)

SIWHP

(psig)

NCG

(wt.%)

H2S

(ppmw)

Cl

(ppmw)

PS-31 55 100 320 3.9 1280 135

PS-31 72 100 465 0.3 550 125

PS-31 93 100 440 0.5 645 15

Flow Testing Geochemistry

Test prior to October 2011 stimulation

January 31, 2012 test results

Northwest Geysers EGS Demonstration Prati State 31 Flow Test Results

June 14, 2012 test results

calpine corporation nw geysers enhanced geothermal system

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