XXXV, No. 2, Pp. 87-188
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Authors: Rui Chen, Cheng-Yuan Luo, Hai-Tao Wang, Zhi-Feng Liu, Xiong-Jie Zhang, Ren-Bo Wang, Shu-Min Zhou, and Bin Tang
Owing to the influence of continuous running of ground water, the uranium atoms can be separated physically from their daughters for the reason of different solubilities and the uranium deposit often shows the disequilibrium feature between uranium and its daughter products (radium principally). It is important, when spectral gamma ray logging, to quantify the uranium content which can cause inaccuracy of the result. This paper, based on spectral γ ray logging method, proposes a neutron-gamma logging method to determine the coefficient of uranium-radium disequilibrium. In this method, characteristic peak count rate of uranium is taken from prompt fission neutron logging, whereas characteristic peak count rate of radium, thorium and potassium are taken from spectral gamma ray logging. Based on this method, the union logging tool including epithermal neutron, thermal neutron, and gamma detector along with D-T generator, have been developed. The experimental results, in standard model wells, show that this method is in good agreement within 7 % in core assay results. It shows that the union neutron-g logging method can be used for field uranium logging jobs.
Key words: prompt fission neutron, spectral gamma ray, uranium logging, disequilibrium coefficient
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