Method for determining density of an earth formation

摘要

Apparatus for determining the density of underground formations surrounding a borehole, such as a wireline logging tool or a logging-while-drilling tool, includes a neutron source for irradiating the formations from within the borehole and at least one detector which detects neutrons and gamma rays in the borehole resulting from the irradiation of the formations with neutrons. Multiple detectors can also be used to separately detect neutrons and gamma rays. Detected neutron and gamma ray signals are each analyzed and combined to determine the density of an earth formation.