Bendix Field Engineering Corp., as a part of the Department of Energy's National Uranium Resource Evaluation (NURE) program, has investigated the feasibility of measuring radon in recirculating drilling mud, and whether the radon variations might be useful for uranium exploration. To implement this program, a prototype instrument was developed and tested. The system works by degassing the drilling mud as it recirculates and by continuously measuring the radon activity of the evolved gas. A record of the relative radon activity, as related to borehole depth, is obtained.

Radon data were obtained at two sites: Sand Wash basin in northwestern Colorado, and the Great Divide basin in south-central Wyoming. At both sites it was found that radon could be measured in the recirculating mud, and the downhole radon profiles paralleled gamma logs obtained from the same drill holes. At the Sand Wash site, the radon content in the mud varied with the lithology encountered. The conglomeratic member of the Browns Park Formation had the highest radon content, twice that of the sand member. The shale of the Mancos Formation had much lower radon levels than either of the other two lithologies. At the Great Divide basin site, the lithology was not as well delineated by the radon profiles.

From this study it was found that radon can be detected in drilling mud and that anomalous radon zones can correspond to uranium concentrations and to variations in lithology. It may also be possible by this method to detect the presence of nearby uranium concentrations.

End_of_Article - Last_Page 898------------