ENVIRONMENTAL CORRECTIONS IN NUCLEAR SPECTROSCOPY USING VARIABLE SHAPE STANDARD

摘要

An aspect of a formation may be estimated by placing a nuclear spectroscopy tool including a neutron source and a gamma ray detector into a borehole and performing a plurality of environmental measurements. Neutrons are emitted from the nuclear spectroscopy tool such that some of the neutrons generate gamma rays from a formation adjacent the nuclear spectroscopy tool, some of the neutrons generate gamma rays from elements within the nuclear spectroscopy tool and some of the neutrons generate gamma rays from an element in the drilling mud. An energy spectrum of gamma rays induced by the emitted neutrons can be detected with the tool. The detected gamma-ray energy spectrum can be analyzed using a combination of standard spectra, where the shape of at least one of the standard spectra can be varied based on the environmental measurements to account for the environment's effects on gamma-ray spectra.