Geochemical Logging With Spectrometry Tools

Abstract

Summary A geochemical logging tool (GLTSM) string, measuring natural, activation, and prompt neutron-capture gamma rays, produces logs of the most abundant and a few trace inorganic element concentrations. Direct measurements of Al concentrations are provided. A geochemically based closure model is used to derive Si, Ca, Fe, S, Gd, and Ti concentrations. The only significant spectroscopically undetermined element, Mg, is inferred by comparing measured with derived photoelectric factor. Analysis algorithms, demonstrations of accuracy and precision, and applications of geochemically derived formation properties are discussed.