US 12,181,626 B2 · Pulsed neutron monitoring of carbon dioxide in reservoirs

Abstract

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.

Claims20

Dependent claims

A method of estimating a saturation of carbon dioxide (CO2) in a formation penetrated by a wellbore using a pulsed neutron (PN) tool deployable in the wellbore, wherein the PN tool comprises a source configured to irradiate the formation with fast neutrons, a first detector spaced a first distance from the source, and a second detector spaced a second distance from the source, wherein the second distance is greater than the first distance, and wherein each detector is configured to detect gamma radiation resulting from the irradiating and arriving at the respective detectors, the method comprising:

for each of the first and second detectors, receiving neutron capture data indicative of neutron capture photons detected at the respective detectors,
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.

1 more element

A system for estimating a saturation of carbon dioxide (CO2) in a formation penetrated by a wellbore using a pulsed neutron (PN) tool deployable in the wellbore, wherein the PN tool comprises a source configured to irradiate the formation with fast neutrons, a first detector spaced a first distance from the source, and a second detector spaced a second distance from the source, wherein the second distance is greater than the first distance, and wherein each detector is configured to detect gamma radiation resulting from the irradiating and arriving at the respective detectors, the system comprising:

a non-transitory computer readable storage medium comprising instructions, which when executed by a computer configure the computer to perform a method comprising:
for each of the first and second detectors, receiving neutron capture data indicative of neutron capture photons detected at the respective detectors,
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.

2 more elements

Dependencies are inferred from the claim text.

Pulsed neutron monitoring of carbon dioxide in reservoirs

Life of this patent

Pulsed neutron monitoring of carbon dioxide in reservoirs

Life of this patent

Abstract

Claims20