Laboratory Characterisation of Basaltic Rocks for Subsurface CO2-Geo-Sequestration by Carbon Mineralisation

Stretched across 500, 000 km2 in west-central India, the Deccan Traps have been recently identified as a potential site for safely and permanently trapping about hundred Gtons per year of CO2 through mineral carbonation, according to recent geochemical and mineralogical studies. However, limited data on the geophysical, petrophysical and geomechanical properties of the various basaltic lithotypes present in the area have been collected. These properties are crucial for an effective and quantitative evaluation of the site's suitability for carbon mineralisation. In order to fill in this knowledge gap, we performed an experimental framework for the petrophysical and rock mechanical characterisation of two different lithofacies (flow-top brecciated and massive) of basaltic rocks collected from the Deccan Volcanic Province. The research was conducted at the Geomechanics and Geophysics Laboratory (GGL) at ARRC, CSIRO Energy, Western Australia. Starting with sample preparation and CT-scanned imaging of the samples, geophysical and petrophysical properties (including bulk density, acoustic velocities, porosity and permeability) have been quantified. Hydrostatic and multi-stage triaxial tests under in-situ conditions (pressure/temperature) have also been conducted to characterise the rock mechanical properties of the basalt samples. This paper summarises the petrophysical and dynamic elastic moduli obtained for a selected suite of samples.