Testing Hyperspectral Remote Sensing Monitoring Techniques for Geological CO 2 Storage at Natural Seeps

Transcription

1 Testing Hyperspectral Remote Sensing Monitoring Techniques for Geological CO 2 Storage at Natural Seeps Luke Bateson Clare Fleming Jonathan Pearce British Geological Survey

2 In what ways can EO help with CO 2 monitoring for CCS? Monitoring subsurface plume location InSAR Indirect CO 2 leak detection Vegetation analysis Via effects on geology (CRIUS project in Utah) Hypespectral direct detection of CO 2 Hyperspectral test at BGS campus Hyperspectral work at natural study site in Italy Hyperspectral work over a large industrial source

3 Latera Study Site CO 2 GeoNet is a network of European research institutes to study Geological CO 2 storage Remote sensing work package to study possible CO 2 leak detection from a terrestrial site. Latera, Italy is a natural test site analogous to a leaking CO 2 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 CO 2 release via thermo-metamorphism Rome Tyrrenian Sea km W Adriatic Sea N S E

4 Latera Study Site Gradoli Latera Bolsena Lake Valentano

5 Indirect CO 2 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

6 Direct Detection of CO 2 using Hyperspectral Data CO 2 absorption feature = 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

7 Direct Detection of CO 2 using Hyperspectral Data Band ratio processing results in noisy image: Atmospheric water vapour has an unequal absorption at the CO 2 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 Interpolated radiance Measured radiance CIBR Radiance m Interpolated _ Radiance m

8 Direct Detection of CO 2 using Hyperspectral Data - Test at BGS

9 True Colour Image of Test Area

10 Test at BGS CIBR result Anomalies detected for white tarpaulin, but also in areas of low signal to noise, such as shadow and across track illumination effects

11 Direct CO 2 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

12 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 CO 2. ASD measurement of CO 2. Measurements of the spectralon reference panel in 2 areas: Outside of the vent assumed no extra CO 2 to be present. Directly over the vent, where we assumed additional CO 2 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:

13 ASD Measurements of CO 2 Average ASD Reflectance values for areas with and without leaking CO2 Reflectance Absorption Depth (reflectance %) Spectralon reflectance no additional CO 2 Spectralon reflectance additional CO Wavelength (nm) Air CO2 Air No CO2

14 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!

15 CIBR for Latera Density slice of the CIBR White = CIBR using hawk band 166 Yellow = ( nm) Cyanthe = Note noise in the shadow area HAWK true colour image Magenta =

16 Why do we not see the CO 2 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?

17 Direct detection of CO 2 using satellite data Freely available Hyperion data Need a site with high CO 2 flux to detect CO 2 in a relatively low resolution satellite image. Hyperion data exists over Baghdad Oil refinery to south of river

18 Baghdad CIBR Reference bands = 183 ( nm) and 189 ( nm) Measurement band = 185 ( nm)

19 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 CO 2 source Direct detection with Hyperion gives promising results over a large industrial site

20 Opportunities for CCS with future ESA Missions Sentinel 1 (C-band Radar) InSAR studies 2 day repeat Sentinel 2 (high res multispectral) Vegetation stress studies Geological mapping Sentinel 5 Atmospheric monitoring will it be sensitive enough to pick up small increases in CO 2 from leaks? Still need - High resolution well calibrated hyperspectral sensors which extend into the thermal region Direct detection via spectral signatures