CPC E21B 47/06 (2013.01) [G01V 5/102 (2013.01)] | 17 Claims |
1. A downhole tool system comprising:
a radiation source configured to emit neutron radiation at a location within a cased wellbore of a geological formation;
a radiation detector configured to determine nuclear radiation at the location within the cased wellbore, wherein the nuclear radiation is based at least in part on nuclear interactions between the neutron radiation and the geological formation; and
processing circuitry configured to:
determine a sigma, a neutron porosity, a fast-neutron cross-section, or a combination thereof, of the geological formation at the location based at least in part on feedback received from the radiation detector indicative of the nuclear radiation at the location within the cased wellbore; and
estimate a gas pressure of the geological formation at the location based at least in part on the sigma, the neutron porosity, the fast-neutron cross-section, or a combination thereof
wherein the processing circuitry is configured to estimate the gas pressure at least in part by:
determining a first estimation of the gas pressure based at least in part on a first one of the sigma, the neutron porosity, and the fast-neutron cross-section; and
determining a second estimation of the gas pressure based at least in part on a second one of the sigma, the neutron porosity, and the fast-neutron cross-section, and
wherein the first estimation, the second estimation, or both are determined based at least in part on assumptions of physical properties of the geological formation at the location based at least in part on additional measurements received by the processing circuitry.
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