Geological Carbon Sequestration

1. Geological Carbon Sequestration Presentation based on articles by S. Julio Friedmann ELEMENTS , VOL. 3, PP. 179–184 JUNE 2007 And Steven Bryant Journal of Petroleum Technology • SEPTEMBER 2007 And IPCC Special Report on Carbon Dioxide Capture and Storage --Storage in Deep Underground Geological Formations – http://www-esd.lbl.gov/co2geostorage/pdfs/MIT_05_finaldraft.pdf

2. http://www.gaylordheraldtimes.com/articles/2007/07/20/news/top_stories/doc46a117da12157500673608.txthttp://www.gaylordheraldtimes.com/articles/2007/07/20/news/top_stories/doc46a117da12157500673608.txt

3. Carbon Capture and Storage Geological storage is a four-step process: • First, a pure or nearly pure stream of CO2 is captured from flue gas or other process stream • Next it is compressed to about 100 atmospheres • It is then transported by pipeline to the injection site • Finally, it is injected deep underground into a geological formation where it can be safely stored for thousands of years or longer http://www-esd.lbl.gov/GCS/gcs-edu-out.html

4. Reservoir characteristics • “The most promising reservoirs are porous and permeable rock bodies, generally at depths of 800 m or greater” Pressure and temperature changes with depth • On average, temperature increases by 25ºC for every 1000 m depth within the earth (average geothermal gradient) • Pressure increases by approximately 270 bars for every 1000 m depth (using density of granite)

5. Fig. 1 of the Friedmann article What is going to be the state of CO2 (solid, liquid or gas) At a depth of 800 m?

6. Under these conditions, CO2 will Act like a liquid, with • a density less than that of brine, • a fairly low solubility in water, and • a viscosity less than that of oil “The high densities are critical to successful storage because a large volume of CO2 can be injected into a limited pore volume.”

7. Storage Options (will also require an impermeable layer as “caprock”) • Deep saline formations • Depleted oil and gas reservoirs • Enhanced oil and gas recovery • Deep unmineable coal seams • Enhanced coal bed methane recovery http://www-esd.lbl.gov/GCS/gcs-edu-out.html

8. http://www-esd.lbl.gov/co2geostorage/pdfs/MIT_05_finaldraft.pdfhttp://www-esd.lbl.gov/co2geostorage/pdfs/MIT_05_finaldraft.pdf http://www-esd.lbl.gov/GCS/gcs-edu-out.html

9. Capacity of Storage Formations http://www-esd.lbl.gov/co2geostorage/pdfs/MIT_05_finaldraft.pdf

10. From Bradshaw and Dance 2005

11. Potential risks • Fractured rock formations, faults, and seismic activity could provide an avenue for CO2 leakage. • Pressure from CO2 injection could trigger small earthquakes. • The cement caps usually placed on the wells could deteriorate when exposed to carbonic acid, which can form when CO2 interacts with saline formations. • Abandoned oil and gas wells that were not sealed to today’s standards could leak. http://www.meic.org/energy/global_warming_pollution/carbon-capture-and-sequestration

12. Potential risks contd. • A sudden and large release of CO2 could pose immediate dangers to people in the vicinity. (This one by the way, has been shown to be groundless. See figure 3 of Friedmann article) • Elevated CO2 concentrations in the shallow subsurface could have lethal effects on plants and subsoil animals, and could contaminate groundwater. • Carbon-laden liquids could mobilize toxic metals and organics and contaminate groundwater. http://www.meic.org/energy/global_warming_pollution/carbon-capture-and-sequestration

13. Potential release pathways and remediation http://www-esd.lbl.gov/co2geostorage/pdfs/MIT_05_finaldraft.pdf