Research on the Application of Neutron Gamma Density in Anomalous Mineral Formations

Le résumé fourni par la source

Neutron gamma density (NGD) plays an increasingly important role in petroleum exploration and development. However, current NGD logging fails to obtain reliable results in anomalous mineral formations (such as anhydrite, halite and coal). To address these issues, the application of NGD logging in anomalous minerals has been studied in this paper. Studies have shown that, compared to the standard formations (dolomite, limestone and sandstone), halite, anhydrite and coal have additional influence on inelastic gamma rays, epithermal neutron distribution, and thermal neutron distribution. This causes additional errors when the gamma and neutron information is used for density calculation. In addition, since the influence mechanisms of different minerals on NGD logging are different, it is necessary to determine the mineral type before conducting NGD correction. Compared to other minerals, halite can be easily distinguished by its very high sigma (thermal neutron capture cross-section) and low apparent density; anhydrite by its high sigma, high density and low neutron porosity; and coal by its very low density and zero neutron porosity. Furthermore, for a given anomalous mineral, the density error of NGD logging has a clear linear relationship with the apparent density, which can be used for density correction. By using the corresponding correction algorithm, the density error of NGD logging can be controlled within 0.025 g/cm3 in anomalous mineral formations. This study can provide guidance for the application of NGD technology in mineral exploration.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.