DETERMINING THERMAL NEUTRON POROSITY FROM NEUTRON-SLOWING DOWN LENGTH, FORMATION THERMAL NEUTRON CAPTURE CROSS SECTION AND BULK DENSITY

摘要

FIELD: physics.;SUBSTANCE: in order to determine at least one formation property calculated from neutron measurements obtained using a downhole tool, the following operations are performed: emitting neutrons from a source in the tool into the formation; detecting neutrons with at least one detector in the downhole tool; calculating a first slowing-down length (L₁) based on the neutron detection results; and deriving a second slowing-down length (L₂) based on the first slowing-down length (L₁).;EFFECT: highly accurate estimation of porous space using a neutron logging tool with an electron source.;18 cl, 8 dwg