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© NERC All rights reserved
Testing Hyperspectral Remote Sensing Monitoring Techniques for Geological CO2 Storage at Natural
Seeps
Luke BatesonClare Fleming
Jonathan Pearce
British Geological Survey
© NERC All rights reserved
In what ways can EO help with CO2
monitoring for CCS?•
Monitoring subsurface plume location•
InSAR
•
Indirect CO2
leak detection•
Vegetation analysis
•
Via effects on geology (CRIUS project in Utah)
•
Hypespectral
direct detection of CO2
•
Hyperspectral test at BGS campus•
Hyperspectral work at natural study site in Italy
•
Hyperspectral work over a large industrial source
© NERC All rights reserved
Latera
Study Site•
CO2
GeoNet is a network of European research institutes to study Geological CO2
storage•
Remote sensing work package to study possible CO2
leak detection from a terrestrial site.
N
EW
S
1000 200 300 km
Rome
TyrrenianSea
AdriaticSea
•
Latera, Italy is a natural test site analogous to a leaking CO2
geological storage site.•
Extinct
caldera structure, known
for:•
High geothermal
gradient•
Cold
and warm
springs•
Gas vents
•
Shallow
carbonate
basement
in which
there
is
high heat
flow
leading
to
CO2
release
via thermo-metamorphism
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Latera
Study Site
Latera
Gradoli
Valentano
BolsenaLake
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Indirect CO2
leak detection
•
NDVI (CASI)•
Thermal (ATM)
•
Aerial photos•
Lidar
intensity
•
Vents mainly identified via changes in vegetation•
White polygons = possible vents
•
Soil gas testing of 39 of these (colour infill) •
40% of our interpretation was correct
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•
CO2
absorption feature = 2.005 microns
•
On the edge of water absorption feature
•
Other atmospheric gasses do not absorb at this wavelength
•
HAWK hyperspectral sensor covers this region
•
NERC Airborne Research and Survey Facility have Eagle and Hawk sensors
Direct Detection of CO2
using Hyperspectral Data
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Interpolated radiance
Measured radiance
•
Band ratio processing results in noisy image:
•
Atmospheric water vapour has an unequal absorption at the CO2
absorption wavelength (λm) and the reference wavelength (λr) .
•
Modify band ratio to account for this unequal water vapour influence…..Use a Continuum Interpolated Band Ratio
Direct Detection of CO2
using Hyperspectral Data
mRadianceedInterpolat
mRadianceCIBR
_
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Direct Detection of CO2
using Hyperspectral Data -
Test at BGS
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True Colour Image of Test Area
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Anomalies detected for white tarpaulin, but also in areas of low signal to noise, such as shadow and across track illumination effects
Test at BGS –
CIBR result
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Direct CO2
detection over natural leaks, Latera
•
NERC ARSF data flown in Italy in September 2007
•
Ground-truthing data also collected.•
Field spectrometer readings (ASD)
•
Soil gas flux to atmosphere •
Soil gas compositions
•
Atmospheric monitoring•
Weather station
•
Eddy covariance
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ASD Measurements•
ASD used for calibration
•
ASD measurements of vegetation surface for a transect across a vent
•
ASD also used try to measure the influence of the additional CO2.
•
ASD measurement of CO2
.
•
Measurements of the spectralon
reference panel in 2 areas:•
Outside of the vent assumed no extra CO2
to be present. •
Directly over the vent, where we assumed additional CO2
to be present.
•
Measurements were made both at ground level and approximately 1 meter from the ground
•
An average was computed for each measurement, the resulting reflectance was graphed for each category:
© NERC All rights reserved
ASD Measurements of CO2
Average ASD Reflectance values for areas with and without leaking CO2
88
89
90
91
92
93
94
95
96
1961
1968
1975
1982
1989
1996
2003
2010
2017
2024
2031
2038
2045
2052
2059
2066
2073
2080
2087
2094
Wavelength (nm)
Ref
lect
ance
Air CO2 Air No CO2
Spectralon reflectance no additional CO2
Spectralon reflectance additional CO2
Absorption Depth (reflectance %)
0.65 3.78
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Latera
Hawk data•
237 spectral bands 920nm to 2500nm (Short Wave Infrared)
•
2 to 4 meter pixel size
•
About 30% of the imagery covered by shadow.
•
Main area of interest is covered by shadow!
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CIBR for Latera
HAWK true colour image
CIBR using hawk band 166 (2003.04nm)
Note the noise in the shadow area
Density slice of the CIBR
White = 0.80 –
0.85
Yellow = 0.85 –
0.90
Cyan = 0.91 –
0.93
Magenta = 0.95 –
0.97
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Why do we not see the CO2
in the Hyperspectral imagery?
•
Semi promising results from BGS test•
ASD results show there is a difference in absorption at wavelengths of interest
•
Possible reasons for not detecting this in Italy:•
Signal to noise ratio of the sensor
•
Cloud shadow –
low signal to noise, but still don’t see vents which are not in shadow
•
Small amount of leakage gas compared to atmospheric gas •
It does not have a large enough effect within the area of an image pixel (3-4m square)?
•
Does it disperse to quickly? –
BGS test suggests this could be a factor
• Background to the gas is too varied?
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Direct detection of CO2
using satellite data
•
Freely available Hyperion data
•
Need a site with high CO2
flux to detect CO2
in a relatively low resolution satellite image.
•
Hyperion data exists over Baghdad
•
Oil refinery to south of river
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Baghdad CIBR
•
Reference bands = 183 (1981.86nm) and 189 (2042.45nm)
•
Measurement band = 185 (2002.06nm)
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Conclusions
•
Indirect detection works 40% of the time
•
Direct detection with HAWK sensor not giving us the results we want for a natural site•
SN ratio?
•
Would be interesting to try over a large CO2
source
•
Direct detection with Hyperion gives promising results over a large industrial site
© NERC All rights reserved
Opportunities for CCS with future ESA Missions•
Sentinel 1 (C-band Radar) 2011.•
InSAR studies
•
2 day repeat
•
Sentinel 2 (high res multispectral) 2012.•
Vegetation stress studies
•
Geological mapping
•
Sentinel 5•
Atmospheric monitoring –
will it be sensitive enough to pick up small increases in CO2
from leaks?
•
Still need -
High resolution well calibrated hyperspectral sensors which extend into the thermal region•
Direct detection via spectral signatures
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