DENSITY MEASUREMENTS USING DETECTORS ON A PULSED NEUTRON MEASUREMENT PLATFORM

摘要

An apparatus for estimating a property of an earth formation and a borehole fluid includes a carrier configured to be disposed in a borehole, and a 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. The apparatus also includes a fluid density measurement assembly including the gamma ray detector and a gamma ray source configured to irradiate a borehole fluid with gamma rays. The gamma ray detector is positioned relative to the gamma ray source to detect both of: gamma rays resulting from neutron interactions and gamma rays emitted from the borehole fluid in response to irradiation from the gamma ray source. The apparatus further includes a processor configured to differentiate a pulsed neutron gamma ray spectrum associated with the interactions from a density gamma ray spectrum.

主权项

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 transmit signals corresponding to the detected gamma rays; 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, the gamma ray source disposed at an axial location of the carrier that is different than an axial location of the pulsed neutron source, wherein the gamma ray detector is positioned relative to the gamma ray source to detect both of: gamma rays resulting from interactions between the neutrons and at least one of the borehole and the formation, and gamma rays that pass through the borehole fluid in response to irradiation from the gamma ray source; and a processor configured to receive the signals from the detector and generate gamma ray spectrum data, the processor configured to differentiate a pulsed neutron gamma ray spectrum associated with the interactions from a density gamma ray spectrum associated with the gamma rays emitted in response to the irradiation.