CO2 sequestration potential in Indian basalts

Banks, Finlay; Vedanti, Nimisha; Lacinska, Alicja; Ougier-Simonin, Audrey; Williams, John; Kilpatrick, Andrew; Bateman, Keith; Fletcher, Cameron. 2023 CO2 sequestration potential in Indian basalts. [Poster] In: The 12th Trondheim Conference on CO2 Capture, Transport and Storage (TCCS-12), Trondheim, Norway, 19-21 Jun 2023. (Unpublished)

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Abstract/Summary

India currently produces 7 – 8% of annual global CO2 emissions, with energy production accounting for 69% of India’s emissions. As such there is growing interest in the potential for emissions reductions through Carbon Capture and Storage (CCS). Vishal et al., (2021) estimated the theoretical storage capacity of India. However, many large emission sources are located distant from sedimentary basin settings where CO2 storage may conventionally be considered. Continental flood basalts of the Deccan Traps cover an estimated 500,000 km3 in west-central India, and have been identified for potential CO2 storage. The concept of CO2 storage in basalt relies on CCS by mineralisation (CCSM) as basalt can act as a ready source of divalent cations such as Mg2+ and Ca2+. These can combine with carbonate, CO32-, from dissolved CO2, to produce carbonate minerals such as Magnesite (MgCO3). The CarbFix project in Iceland is a successful example of CCSM in basalt. CO2 is captured from the industrial emission site and piped to the CarbFix operation, where CO2 gas is dissolved in water to produce carbonated water and injected into the basalt (Matter and Kelemen, 2009). A key point to note is that a successful basalt storage scheme requires a target formation with sufficient porosity and permeability to sustain the required injection rates. We present an experimental study focused on characterising basalt of the Ambenali and Poladpur formations sampled from the Killari-1 borehole to assess the storage potential of Deccan Trap basalts. A density log for the Killari-1 borehole is shown in Figure 1, illustrating significant physical property variations throughout the site. Rubbly flow tops and vesicular layers which may be considered as potential injection intervals can be identified from the density log. Higher density layers may act as low permeability top seals. X-ray computed tomography (CT) was performed on six selected core samples (c. 120 mm in length and 54 mm in diameter) using a Geotek rotating X-ray computed tomography (RXCT) core scanner at the British Geological Survey’s (BGS) Core Scanning Facility (CSF). Sample depths are shown on Figure 1. Total and connected porosity was calculated using digital rock analysis (PerGeos by ThermoFisher). Figure 2 illustrates the porosity network for sample KIL-110 taken from a low-density zone at a depth of 231 m. The left image (blue) shows total porosity, while the right image (purple) shows total connected porosity which is 15.57%. For comparison, KIL-123, at a depth of 168 m has no porosity and is therefore unlikely to contribute to fluid flow unless open fractures or joint networks are present. Previous geochemical experiments carried out on Deccan Trap samples have indicated that major dissolution of primary carbonates and precipitation of secondary minerals such as siderite occurs during CO2 exposure. This confirms the potential for mineral trapping of CO2. Using samples from the Killari-1 borehole, a new series of experiments has been initiated to explore these geochemical processes more fully, including the reaction rates and implications for CO2 storage. An ongoing series of batch experiments using powdered basalt samples at a range of temperatures is currently underway, with regular fluid sampling and monitoring to provide valuable information on reaction rates. The experiments are conducted under 100 bar CO2 headspace and at temperatures of 50°C, 100°C and 150°C. As well as providing some relatively high temperature data points where reactions will progress more rapidly, the selected temperature range reflects the significant variation in geothermal gradient across the Deccan Volcanic Province. SEM and XRD reacted solids will provide information on changes from pre to post experiment. The experiments will be complemented by additional batch experiments conducted at similar conditions using cut, rather than powdered sample material. As well as generating more realistic data on reaction rates, this approach will enable detailed characterisation of the reacted material surfaces through a before and after comparison of specific surface sites via SEM. A subsequent suite of flow-through experiments will be conducted on core samples to investigate the impact of flowing water with a high dissolved CO2 content through the basalt. These experiments will enable the assessment of the dissolution and precipitation potential of porous basalt systems, and, therefore, the potential impacts on flow within a representative flow zone. Effluent chemistry will be monitored to assess directions and rates of reaction within the system, allowing an assessment of the storage potential of Deccan Trap basalts. The experiments will be conducted under pressure and temperature appropriate to potential storage depths. Acknowledgements The research was part of the BGS International NC programme ‘Geoscience to tackle Global Environmental Challenges’, NERC reference NE/X006255/1. Nimisha Vedanti acknowledges ECCSEL-ERIC for supporting transnational access to ECCSEL research infrastructure at the British Geological Survey. The Director, NGRI is acknowledged for permission to conduct research on NGRI Basalt samples. The extended abstract is published by permission of the Director of the British geological Survey. References Gupta, H.K., Srinivasan, R., Rao, R.U.M., Rao, G.V., Reddy, G.K. and others. 2003. Borehole investigations in the surface rupture zone of the 1993 Latur SCR earthquake, Maharashtra, India: Overview of results. Memoir of the Geological Society of India, 54, 1–22. Matter, J., Kelemen, P. 2009. Permanent storage of carbon dioxide in geological reservoirs by mineral carbonation. Nature Geosci 2, 837–841. Vishal, V., Verma, Y., Chandra, D. and Ashok, D. 2021. A systematic capacity assessment and classification of geologic CO2 storage systems in India. International Journal of Greenhouse Gas Control, 111, 103458.

Item Type:	Publication - Conference Item (Poster)
Additional Keywords:	IGRD
Date made live:	03 Jul 2023 11:43 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/535122

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