Ultrasonic velocity data for quartz sands during CO2-brine injection experiment

Time-series measurements of ultrasonic P-wave and S-wave velocities from quartz sands obtained during cyclic CO2-brine injection. The measurements were conducted under high-pressure conditions using piezoelectric transducers and capture elastic property changes during repeated injection and hold periods. Velocity changes represent percentage changes relative to a reference velocity defined for each experiment. Velocity ratio difference represents the difference relative to a reference velocity ratio.