Patent ID: 11892589
Assignee: CHINA PETROLEUM & CHEMICAL CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  E | IPC E  G

Claim 0:
1. A method of evaluating downhole formation porosity, comprising:
emitting neutron pulses from a pulsed neutron tool deployed in a wellbore to irradiate earth formation surrounding the wellbore;
detecting neutrons and gamma rays using a plurality of detectors disposed in the pulsed neutron tool, wherein each detector is operable to detect neutrons and gamma rays from the formation; and
estimating a plurality of neutron porosities and a plurality of gamma-ray porosities based on data from the plurality of detectors,
wherein the estimating step comprises:
obtaining a neutron count rate and a capture gamma-ray count rate from each of the plurality of detectors;
calculating a ratio of neutron count rate and a ratio of capture gamma-ray count rate between every two of the plurality of detectors so as to obtain a plurality of ratios of neutron count rate and a plurality of ratios of capture gamma-ray count rate; and
estimating a plurality of neutron porosities using the plurality of ratios of neutron count rate and/or estimating a plurality of gamma-ray porosities using the plurality of ratios of gamma-ray count rate.