Evaluating impacts of CO2 gas intrusion into a confined sandstone aquifer: Experimental results

Nikolla P. Qafoku, Amanda R. Lawter, Hongbo Shao, Guohui Wang, Christopher F. Brown

Research output: Contribution to journalConference articlepeer-review

Abstract

Deep subsurface storage and sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Experimental and modeling work is required to evaluate potential risks to groundwater quality and develop a systematic understanding of how CO2 leakage may cause important changes in aquifer chemistry and mineralogy by promoting dissolution/precipitation, adsorption/desorption, and redox reactions. Sediments from the High Plains aquifer in Kansas, United States, were used in this investigation. This aquifer was selected to be representative of consolidated sand and gravel/sandstone aquifers overlying potential CO2 sequestration repositories within the continental US. In this paper, we present results from batch experiments conducted at room temperature and atmospheric pressure with four High Plains aquifer sediments. Batch experiments simulate sudden, fast, and short-lived releases of the CO2 gas as would occur in the case of well failure during injection. Time-dependent release of major, minor, and trace elements were determined by analyzing the contacting solutions. The strong acid extraction tests confirmed that in addition to the usual elements present in most soils and sediments, the High Plains aquifer sediments had appreciable amounts of As, Cd, Pb, Cu, and occasionally Zn, which potentially may be mobilized from the solid to the aqueous phase during or after exposure to CO2. However, the results from the batch experiments showed that these sediments mobilized only low concentrations of trace elements (potential contaminants), which were detected occasionally in the aqueous phase during these experiments. Importantly, these occurrences were more frequent in the calcitefree sediment. Results from these investigations provide useful information to support site selection, risk assessment, and public education efforts associated with geological CO2 storage and sequestration.

Original languageEnglish (US)
Pages (from-to)3275-3284
Number of pages10
JournalEnergy Procedia
Volume63
DOIs
StatePublished - Jan 1 2014
Externally publishedYes
Event12th International Conference on Greenhouse Gas Control Technologies, GHGT 2014 - Austin, United States
Duration: Oct 5 2014Oct 9 2014

Keywords

  • Aquifer quality
  • CO gas leakage
  • Ion exchange
  • Major
  • Mineral dissolution
  • Minor and trace elements release

ASJC Scopus subject areas

  • Energy(all)

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