Natural Gamma Ray Emissions in The Muddy J Formation in Eastern Wyoming


W. S. Donovan
Dugan Production Corp. , D. W. Hilchie
Colorado School of Mines

7th Formation Evaluation Symposium of the
Canadian Well Logging Society in Calgary, October 21, 22, 23 & 24, 1979



A laboratory study of the gamma ray emissions from clean and shaly parts of the Muddy J formation of Eastern Wyoming show that there are relationships between the cation exchange capacity and the uranium originating radiation. In fact, the major source of radioactivity in the shales and shaly sands appears to be of uranium origin. In short, the gamma ray log, as Thompson and Linke found, is more of a cation exchange capacity log than a shale log. The findings of this study may also force us to re-evaluate the theory of the source of shale radioactivity.