Self-sealing of Wellbore Cement under the CO2 Batch Experiment Using Well Composite Sample

Abstract

We studied the self-sealing behavior of wellbore cement due to chemical reaction between Portland cement and CO2 by CO2 batch experiment using a well composite sample having a CO2 leakage pathway. To generate the CO2 leakage pathway in the well composite sample, a gelatin-beads dumbbell put inner wall of the hole of a cylindrical Berea sandstone, and a Portland cement slurry was poured into the hole. After the batch experiment, higher density zone due to precipitation of calcium carbonate was clearly observed around the CO2 leakage pathway. The void and channel sizes were decreased significantly while part of channel size was barely increased. In addition, partial channels were completely clogged. This result indicated that the evidence of self-sealing of Portland cement by CO2 chemical reaction.