Center for Geologic Storage of CO2

The specific objectives of this work are the following: 1) To determine the effect of geochemical reactions on geomechanical rock properties at the nano and continuum (core) scale. 2) To determine the effects of geochemically induced to geomechanical rock properties on rock fracturing Immediately upon injection, CO2 will sorb onto the reservoir minerals and will dissolve into brine. Clay is expected to swell within hours to days upon CO2 adsorption, and this is expected to decrease the available pore space, and to increase the local strain. The CO2 dissolved in brine is present as carbonic acid. It is expected to promote dissolution on the time scale of weeks to months for clays, and on the time scale of years to decades and even centuries for the most stable silicates. Minerals that dissolve in short time scales often act as binding agents for more stable minerals. Hence, their dissolution is expected to weaken the strength of the reservoir rock. Greater in situ stress from clay swelling, and dissolution of grain binding agents, are both expected to promote fracturing along grain boundaries.