BOREHOLE INVARIANT NEUTRON POROSITY MEASUREMENT SYSTEM

摘要

This invention is directed toward the determination of porosities of earth formations penetrated by a borehole, and more specifically is directed toward the determination of porosities of earth formations while the borehole is being drilled. Borehole invariant neutron porosity measurements are obtained using a borehole tool which provides the response of two detectors spaced axially at different spacings from a neutron source. No independent measure of borehole geometry is required to correct the resulting porosity measurements for variations in borehole size or variations of the position of the borehole tool within the borehole.