Subsurface CO_2 leakage: Lab-scale study of salient characteristics and assessment of borehole-based detection using resistivity tomography

摘要

A unique laboratory facility is developed for the observation of subsurface CO_2 leakage evolution. A thin transparent tank is filled with different sizes of glass-beads to form controlled layered stratigraphies; then the medium is saturated with water mixed with a universal pH indicator. The flow-controlled injection of CO_2 is carefully controlled using pressure transducers with precise needle valve and, time-lapse photography permits capturing the evolution of gas invasion and diffusion. Results show the nature of CO_2 gas migration in the near surface, the effect of fine-grained layers such as the cap-rock, water acidification near conduits and subsequent diffusion, the convection of carbonated water. In addition to this trial to understand salient characteristics on subsurface CO_2 leakage, applicability of borehole based resistivity tomography is assessed. Measurement system for resistivity tomography is attached to the CO_2 gas migration monitoring system. Produced resistivity images are compared with time-lapse digital images taken during CO_2 gas leakage simulation.