WATER SATURATION DETERMINATION USING AN OXYGEN ESTIMATE AND FORMATION LITHOLOGY

摘要

Borehole logging methods for estimating a parameter of interest using nuclear radiation. Methods include estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen. This may include using at least one processor to: obtain a gamma ray count measurement, representing gamma rays from one of (i) the decay of nitrogen-16 (ii) and the inelastic scattering, and estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.

主权项

1. A method for estimating at least one parameter of interest of a formation, comprising:
estimating a water saturation of the formation from gamma radiation from at least the formation detected in the borehole using a radiation detector, the gamma radiation responsive to a pulsed neutron source and resulting from at least one of: (i) decay of nitrogen-16 formed by activation of oxygen-16, and ii) inelastic scattering of neutrons from oxygen, by using at least one processor to:
obtain a gamma ray count measurement, representing gamma rays from one of: (i) the decay of nitrogen-16 (ii) and the inelastic scattering, via spectral stripping of gamma rays from a measured gamma ray spectrum of the detected gamma radiation,estimate the water saturation using the gamma ray count measurement and a model comprising a relationship between measured gamma ray counts and modeled gamma ray counts from each of a fully water saturated formation and a minimally water saturated formation.