Understanding the acoustic emission from gas bubble dynamics: a signature of CO₂ leakage

The identification and characterization of CO₂ leakage signatures in water and other fluids are of interest in the geophysical study of geysers and aquifers. As several DOE programs are investigating the feasibility of operationally injecting CO₂ into the subsurface, detecting and characterizing the signatures associated with the interaction of CO₂ with water shows important implications for monitoring large scale Carbon storage. This project proposes the development of a laboratory-scale test bench to carry out experimental studies of the acoustic emission emanating from gas bubble dynamics in a bi-phasic (water and gas mixture) fluid system. Different air bubble sizes, varying from 1 cm to 10 cm, are injected from the bottom of a water bath. As the bubbles migrate to the top, the vibrational response of those bubbles is captured by an acoustic pressure sensor placed within the fluid. The interaction is expected to be dependent on the size of the bubble, which can be characterized using the recorded acoustic signal. The result provides a non-invasive technique for characterizing the air bubble-size in the water/gas system and enables us to develop a framework for determining signatures pertaining to the presence of CO₂ in water.