Three‐dimensional acoustic monitoring and modeling of a deep‐sea CO₂ droplet cloud

Abstract

We show that release of 5 liters of liquid CO 2 at 1000 m depth can be readily detected acoustically, and tracked for over 30 minutes, and 150 m of ascent, with both surface ship (38 kHz) and ROV (675 kHz) sonars. The released liquid broke up into droplets covered with a hydrate film. The remarkably sensitive acoustic response of the droplets may be attributed to the high sound speed contrast between CO 2 (300 m/sec) and sea water (1500 m/sec), the near spherical shape of the droplets created by the hydrate shell, and the high compressibility of the liquid. The observed cloud conformed closely to models of CO 2 disposal, allowing for reasonable predictions of larger scale processes. This offers a remarkably sensitive technique for examination in real time of engineered releases of CO 2 , volcanic sea floor liquid CO 2 plumes, or leakage from geologic CO 2 storage.