Pulsed Neutron Monitoring of Carbon Dioxide in Reservoirs

Methods, tools, and systems for determining CO2 saturation in a porous formation using pulsed neutron logging are described. Embodiments of a pulsed neutron logging tool feature a pulsed neutron generator configured to emit pulsed neutrons into the formation and at least two detectors configured to receive emitted photons. The first detector is located closer to the neutron generator than the second detector. Embodiments of the method involve determining first detector formation capture counts indicative of neutron capture photons originating from the formation and detected at the first detector, determining second detector borehole capture counts indicative of neutron capture photons originating from the borehole and detected at the second detector, using the first detector formation capture counts and the second detector borehole capture counts to estimate the saturation of CO2 in the formation.