CO2 Leakage: A Matter of Concern?

Question

1. If CO2 emission remains to be dangerous, then, CO2 leakage is not a concern?

2. Should CO2 migrate from the storage reservoir, multiple processes will attenuate the CO2, such that the likelihood of CO2 reaching the surface always remains to be low?

3. Did &#x2018;CO2 injected at ZERT&#x2019; NOT arrive at the surface within ~5 h?

4. Were CO2 bubble streams NOT observed at QICS within 3 h of injection commencing?

5. Given the spatial and temporal distribution of CO2 degassing, is it NOT difficult to take continuous or detailed measurements of the seep site?

6. How about CO2 getting migrated beyond the initial monitoring boundaries and which makes it difficult to estimate the relative proportions of CO2 that leaked to surface, remained in soil gas or dissolved?

7. Whether, the loss of injected CO2 volume greater than 0.1% per year really negate any benefits from carbon geo-sequestration, highlighting the need for quick and accurate leak detection?

8. Whether, improperly sealed wellbores present the most likely pathways of CO2 leakage?

9. With moderate to high leakage risk from existing bore-wells in CCUS; and with variable seal risk from high formation pressures in CCS (CCS/CCUS being a low-risk method for long-term CO2 storage but not a zero-risk method); don&#x2019;t we have a possibility of ending up with CO2 poisoning upon breathing air with 5% or more CO2 by volume?

10. Are we completely avoiding (a) areas with large numbers of old wells? (b) storage site areas having complex geo-mechanical attributes (c) areas with deteriorated seal rocks? And (d) areas with elevated formation pressure?

11. As of now, predominantly, whether, the studies from oil and gas industries remain to be more focused on loss of integrity rather than leaks (containing leak rates, probabilities and their duration)?

12. No possibility on the leakage of CO2 from transport pipelines, presenting a hazard to humans and animals in the area of the released gas cloud?

13. No possibility on the leakage of CO2 from the installation and from intermediate storage points?

14. No possibility on the leakage of CO2 from the CO2 storage tank in ports during sea transport?

15. In the absence of having details on True Abandoned Well Density; and also on the details of number of active wells that got converted into plugged and intact wells, how could we forecast, whether, we are going to have a continuous leakage or discrete leakage (either minor or major with blowouts) of CO2, following CO2 injection (as a function of number of injection wells and the area of the injected CO2 volume)?

16. How about a scenario, where, there is a sudden, fast and short-lived release of CO2 as would occur in the case of well failure during injection or spontaneous blowouts?

17. How about the local leakage scenario, where, the leak remains to be more gradual, and occurring along undetected faults, fractures or well linings? If such diffusive leakage remain undetected for prolonged periods of time, then, would it have the greatest potential to cause broad-scale environmental impacts?

18. If monitoring by remote sensing provides large coverage and rapid detection without the need for invasive or disruptive installations, then, whether, the existing spectroscopic methods suffer from absorption interference when attempting to detect CO2 directly from storage sites? Or, a ground surface deformation detection would be able to provide a precise leak location?

19. Feasible for a sudden depressurisation caused by a leak could result in a boiling liquid expanding vapour explosion (BLEVE), upon CO2 causing pipeline corrosion?
20. How about the CO2 leakage occurred in 1986 in Cameroon (not from a pipeline or industrial operation but from a lake)?

21. How about the magma chamber underneath Lake Nyos releasing 1.6m t of CO2 which killed more than 1,700 people, thousands of livestock, and destroyed trees and vegetation around the lake?

22. How about 15 t of CO2 release from a fire-extinguishing installation in M&#xF6;nchengladbach in Germany in 1008 that spread outside into the still air intoxicating 107 people, 19 of whom were hospitalised?

23. How about the leak of CO2 from a pipeline operated by Denbury in the US in 2020 that hospitalised 45 people and led to the evacuation of residents from the nearby town of Satartia? [the likely cause being the pipeline rupturing by a landslide following heavy rains and the cloud of CO2 dissipated slowly because of local weather conditions and the contours of the surrounding land]

24. As on date, is there a standard unit for reporting CO2 release rates into the subsurface (mass or volume per unit time); and CO2 fluxes (CO2 leaked per unit area) from land surface or seabed to atmosphere or water column? Can we differentiate between CO2 release rates and CO2 fluxes in a typical CO2 storage site?

25. Upon CO2 injection into an aquifer, where brine containing not only extremely high salt levels but often heavy metals, hydrocarbons, and radioactive elements; whether, brine leaks, therefore, can be even more worrying than the escape of CO2?

Suresh Kumar Govindarajan, Professor [HAG]

IIT Madras 18-Dec-2024

George H Shaw · Answer

It depends on where it is coming from, the precise location of the leakage, the amount that is leaking per unit time, and the likely ultimate volume of the leakage. There is no simple answer to this question without know most or all of these things.

CO2 Leakage: A Matter of Concern?

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