An Analysis of CO2-driven Cold-water Geysers in Green River, Utah and Chimayo, New Mexico

Abstract

The eruption periodicity, CO2 bubble volume fraction, eruption velocity, flash depth and mass emission of CO2 were determined from multiple wellbore CO2-driven cold-water geysers (Crystal and Tenmile geysers, in Utah and Chimayó geyser in New Mexico). Utilizing a suite of temporal water sample datasets from multiple field trips to Crystal geyser, systematic and repeated trends in effluent water chemistry have been revealed. Crystal geyser has a four part eruption cycle composed of a minor eruption period (mEP), major eruption period (MEP), aftershock eruption period (Ae) and recharge (R). Tenmile geyser has a four part eruption cycle composed of MEP, drainage (D), mEP and R. Chimayó geyser has a two part eruption cycle composed of a MEP and R. The MEP at Crystal geyser currently lasts for over 24 hours highlighting the potential for a natural geyser to reach quasi steady state discharge. At shallow depths the bubble volume fraction ranges from 0 to 0.8, eruption velocities range from 2 to 20 m/s and flash depths are predominately shallow ranging from 5 to 40 meters below the surface. Annual emission of CO2 is estimated to be (4.77±1.92)×103, (6.17±1.73)×101, (6.54±0.57)×101 tonnes/yr for Crystal, Tenmile and Chimayó geysers, respectively. Inverse modeling of endmembers for the mEP at Crystal geyser show that the effluent is comprised of 66%, 33% and 1% the Navajo Sandstone, Entrada Sandstone and Fault Brine, respectively. The range of input for the Navajo, Entrada and Brine during the MEP is 53-57%, 42-45% and 1-2%, respectively. The geyser plumbing geometry consists of a vertical wellbore which allows for the upward migration of CO2-rich fluids due to artesian conditions. The positive feedback system of a CO2-driven eruption occurs within the well. Mitigating high velocity CO2-driven discharge from wellbores will, however, be easier than mitigating diffuse leakage from faults or into groundwater systems.