CO 2 injection to granite and sandstone in experimental rock/hot water systems

Abstract

Experiments were conducted using a batch type micro-autoclave over a temperature range of 100–350 °C to understand granite and sandstone reactions in hot water in the absence or presence of excess CO 2. Our experiments, for one-week duration, show that the dissolution of granite and sandstone, and the deposition of secondary minerals, is enhanced by the presence of excess CO 2. Major element concentrations of the residual solution from the batch autoclave experiments were higher for the rock (granite or sandstone)/H 2O/CO 2 system, than in the rock (granite or sandstone)/H 2O system, but the sample weight loss was lower in the rock/H 2O/CO 2 system than in the rock/H 2O system. Changes in sample weight and CO 2-gas volume content concur with the deposition of aluminium silicate and calcium-aluminosilicate secondary minerals, which indicate fixation of CO 2 in the rock. Our results suggest that it may be possible for granite and/or sandstone to ‘capture’ CO 2, at hydrothermal conditions, and that underground disposal may be a feasible solution to reducing atmospheric emission of CO 2.