The evolution of fractures in an oil shale from in situ synchrotron XR-microtomography experiments at different conditions

The behavior of fractured shales in contact with CO2 fluids can have many implications in the understanding of important subsurface processes. In a scenario of geological carbon sequestration shales are often seen as ideal caprocks, as a principle the very low permeability of the material makes them a perfect candidate for the task, but in a realistic scenario fractures often exist and in contact with reactive fluids the self-enhancing or self-sealing behavior can drive very different outcomes. From an unconventional oil recovery perspective, the evolution of a fracture, either propped or not, can also make a huge difference in the efficiency of the oil/gas recovery process.

The presentation will show different scenarios where these topics have been investigated at the micron resolution, at reservoir conditions, using synchrotron X-ray microtomography. We'll see a wormholing effect and the development of a leached layer resulting from slow flow of an aqueous CO2 in a simple fracture. Also the differences of (fast) flowing liquid CO2 and aqueous CO2 in a propped fracture will be presented, showing interesting differences about the evolution of the fracture characteristics and the effect of the proppant sand grains, with implications on practical applications.

Speaker: Marco Voltolini, Lawrence Berkeley National Labs

Room 104