Patent ID: 9599743
Date: 2017-03-21
CPC Classifications: E21B,G01N,G01T,G01V

Claim:
1. An apparatus for estimating at least one property of an earth formation and a borehole fluid, comprising: a carrier configured to be disposed in a borehole in the earth formation; a pulsed neutron measurement assembly disposed at the carrier, the pulsed neutron measurement assembly including a pulsed neutron source configured to emit neutrons into the borehole and the earth formation, and a gamma ray detector configured to detect gamma ray signals during a pulsed neutron measurement cycle; a fluid density measurement assembly disposed at the carrier, the fluid density measurement assembly including the gamma ray detector and a gamma ray source configured to irradiate a borehole fluid with gamma rays, wherein the gamma ray detector is positioned relative to the gamma ray source to detect gamma ray signals including both of: pulsed neutron gamma ray signals including gamma rays resulting from interactions between the neutrons and at least one of the borehole and the formation, and gamma density signals including gamma rays that pass through the borehole fluid in response to irradiation from the gamma ray source, the gamma ray detector configured to detect the gamma ray signals during a plurality of different selected time gates within the pulsed neutron measurement cycle, the plurality of selected time gates including one or more first time gates associated with the pulsed neutron gamma ray signals and one or more second time gates associated with the gamma density signals; and a processor configured to receive the gamma ray signals from the detector and generate gamma ray spectrum data, the processor configured to differentiate a pulsed neutron gamma ray spectrum associated with the pulsed neutron gamma ray signals from a density gamma ray spectrum associated with the gamma density signals based on a time during the pulsed neutron measurement cycle at which gamma rays were detected.