Dr Ziqiu Xue, Chief Researcher of the CO2 Storage Group at Japan’s Research Institute of Innovative Technology for the Earth (RITE) will lead a Global CCS Institute webinar to review and discuss microseismic monitoring at CCS storage sites. The secure storage of carbon dioxide (CO2) in deep geological formations requires a sufficient overlying cap rock layer to contain the CO2 within the formation. Injection of CO2 increases the formation pressure in the target reservoir. This will decrease the effective pressure and will also lead to geomechanical deformation of the rocks. Therefore, to ensure safety of storage, the CO2 injection must be controlled to maintain integrity of the cap rock. This webinar will give a simple review on microseismic monitoring results observed at onshore CO2 injection sites such as Weyburn, Canada and Lacq, France. Case study results from the Nagaoka pilot site in Japan will also be introduced, including the field survey results after an earthquake hit the area during CO2 injection.

1. Microseismic Monitoring at the CCS fields
-- What we learned from Nagaoka --
Ziqiu Xue (xue@rite.or.jp)
Research Institute of Innovative Tech for the Earth

2. Contents
Previous studies of fluid injection
Geothermal and oil fields
Seismicity at CO2 injection fields
Weyburn (Canada), Lacq (France)
Fi ld survey results at N
Field lt t Nagaoka
k
after the two earthquakes(2004,2007)
CO2 Retention (well log, x-well seismic)
Caprock & Wellbore integrity

3. Fluid Injections:
Stimulation & Production at geothermal and oil fields
S Site Activity Rock
R k Sensors Wells
Unconsolidated
sandstone
Low porosity
Hot-Dry Rock
Granite
Phillips et al, 2001

4. Lessons from Previous Fluid Injections
Microseismic monitoring must be performed by
downhole i t
instruments due to the small size
t d t th ll i
Most events fall in the magnitude - 4 to -2 range,
2
formed surrounding the injection point.
Microseismic techniques equally useful if sufficient
 f l f ff
events observed in sedimentary reservoirs.
Lower Frio: 54 located from 2900 events (too small for location).
Clinton Co.: 3200 events recorded clearly associated with
Co :
production rate, with time lag.
Fenton Hill: over 11,000 locatable events recorded in a volume
11 000
of 1 km x 1 km x 300m.

5. Contents
Previous studies of fluid injection
Geothermal and oil fields
Seismicity at CO2 injection fields
Weyburn (Canada), Lacq (France)
Fi ld survey results at N
Field lt t Nagaoka
k
after the two earthquakes(2004,2007)
CO2 Retention (well log, x-well seismic)
Caprock & Wellbore integrity

6. Microseismic Monitoring at Weyburn
g y
CO2-
CO2-EOR field
Verdon, 2010
8-level, 3-components geophones installed in well 101/06-08, about 50 m away
from injection well 121/06-08, CO2 injection rate 100-500 ton/day, 2003.8 – 2004.11

7. Map (a) and East-West cross-section (b) view of
p( ) East- cross- ( )
Phase 1B events plotted by Verdon (2010)
Yellow: pre-injection (Aug-Dec 2003); Magenta: initial injection period (Jan-Apr 2004);
Red: during elevated
Red d ring ele ated injection rate period (J l No 2004) b Verdon (2010)
(Jul-Nov by (2010).

8. Event magnitudes plotted as a function of
distance from the array by V d (2010)
di f h b Verdon
the limit of detectability
Verdon, 2010

9. Summary of Microseismic Monitoring
at Weyburn CO2-EOR field
CO2-
Event magnitudes ranged between -3 t -1, even
E t it d db t 3 to 1
magnitudes of -2 are still detectable over 400 m away.
Comparison with production data, the timing of events
located in and just above the reservoir correlates with
periods temporarily stopped production.
Microseismicity occurs at the onset of CO2 i j ti
Mi i i it t th t f injection,
and also appears to correlate with periods of increased
injection.
Events are characterized by a low dominant frequency
(15 - 80 Hz) and poor signal-to-noise ratio.

10. Billiot (2011)
( )

11. Billiot (2011)

12. Microseismic Monitoring at the Offshore
Potential Storage Sites in Japan
Observation Well Injection Well
j CO2
Seismometer
OBS
OBC
Seismograph
g p
Hi-net
Hi net Seismograph
Caprock
CO2 plume
Saline Aquifer
Downhole Geophones
(Cemented or Clamped) Natural Seismicity

13. Waveforms of a Natural Seismicity by OBC
Vertical (Z） Sea side
M=0.6 P
offshore Japan
(depth: 100km)
Horizontal （Y1）
Permanent OBC
(Ocean Bottom Cable) S
 4D Seismic Survey
 Microseismic Monitor Horizontal （Y2）
(hydraulic fracturing)
Magnitude: -3.0
Chambers et al., 2010 S

14. Contents
Previous studies of fluid injection
Geothermal and oil fields
Seismicity at CO2 injection fields
Weyburn (Canada), Lacq (France)
Fi ld survey results at N
Field lt t Nagaoka
k
after the two earthquakes(2004,2007)
CO2 Retention (well log, x-well seismic)
Caprock & Wellbore integrity

15. Microseismic Monitoring at Nagaoka Site
Protective case
GPS Antenna
A t
100m Seismic sensor
(3C)
3C Seismic
sensor
→To Recorder
Concrete base
Pavement
Seisimic sensor specifications
Item specification
Seismic Sensor Sensor type: triaxial EpiSensor force balance accelerometer
(ALTUS Enta; Kinemetrics) Full scale: ±2G
Frequency range: DC～100Hz
Dynamic range: 135dB
Seismic Recorder Number of channels: 6ch
(ALTUS –K2; Kinemetrics) Sampling time: 20, 40, 50, 100, 200, 250Hz
Frequency range: DC～40Hz（in 100Hz sampling case）
Dynamic range: 114dB（19Bit）
Power supply: Internal battery 12V, 12Ah

16. Geophysical Monitoring (incl. earthquake safety surveys)

17. Pressure Changes at Injection and Observation Wells
Formation Pressure
Bottom Hole Pressure

18. hypocenter

19. The Mid Niigata Prefecture Earthquake in 2004
NS
N-S
Earthquake
ents
umber of Eve
E-W
EW
Nu
U-D
Date
Histogram of microseismic events by
the i i
th seismic sensor of Nagaoka site.
fN k it
Injection period is July 2003 to January
2005.
Earthquake Wave-forms observed by the Natural earthquakes and surface noises
seismic sensor of Nagaoka site are included in these events.

20. Likely Events Recorded at Nagaoka Site
y g
(2004.10.23 - 2006.3.6)
1000
total events
イ ントの累積数
イベントの累積数
地震類似波形のイベントの累積数
likely events
event count
地震類似波形のイベント
ounts
ト数
100
E イベント
Event Co
10
Likely events appeared just after the earthquake
1
0 100 200 300 400 500
minated
itoring
06
ection
23
29
10
18
26
arted
/
/
/01/
/
/
/
6/03
4/10
5/05
5/08
5/11
ded
005
Re-sta
200
End
200
200
200
200
Term
Inje
Moni
2
Date

21. Likely Events Observed from starting
y g
injection to Mid-Niigata Earthquake
Mid-
21

22. Comparison with Hi-net data
Hi-
JK005 IY087 JJ017
2004/10/06
/ / 2004/05/03 2004/09/10
（injection） （injection）
（i j i ）
JJ005の記録開始時刻 IY087の記録開始時刻
JJ017の記録開始時刻
JJ013
JL009 2004/09/09
2004/10/17 （injection）
: matched event
JJ013の記録開始時刻
IY065
JL009の記録開始時刻
JJ016
2004/04/17 2004/09/10
（suspended） （injection）
IY065の記録開始時刻 JJ016の記録開始時刻

23. Comparison with Hydrophone data
ith H drophone
: matched with Hydrophone record，phase lag in P，S-waves
record phase P S-waves
→ possibly seismic event
: no record in Hydrophone data，no phase lag in P，S waves
P，S-waves
→ Noise

26. Ultra Sonic Imager  Cement Evaluation
casing-to-cement bond quality
Depth OB2 2001/12 (USI) OB2 2005/2 (USI) OB2 2011/10 (BHATV)
(m)
0° 90° 180° 270° 0° 0° 90° 180° 270° 0° 0° 90° 180° 270° 0°
1070
1080
1090
1100
1110
1120
1130

27. Field Surveys after the Earthquakes
Field survey results after the Mid-Niigata and Chuetsu-
Mid Niigata Chuetsu
Oki Earthquakes indicated the safety of CO2 storage at
Nagaoka site.
No sign of CO2 leakage from the reservoir and no
damages in Caprock and Wellbores from formation
pressure measurements and results of geophysical well
loggings and cross well seismic tomography.
cross-well
Ultra Sonic Imager and BHATV surveys indicated
no clear changes in cement even at the depth where
the Class-A cement has been exposed to CO2 for about
8 years at observation wells OB 2 and OB 4
OB-2 OB-4.

28. Acknowledgements
• This project is funded by Ministry of
Economy,
Economy Trade and Industry (METI) of
Japan.
• We thank staff of ENAA, GSC, OYO, GJI
ENAA GSC OYO
and RITE involved in this project.