It is now possible to relate most oil and gas reserves to six stratigraphic black shale formations which include the majority of the world's oil and gas source rocks (Ulmishek and Klemme, 1990). From 1997 the US Dept of Energy attempted to predict the activity of NORM and other factors which may affect the activity and / or occurrence of NORM in E&P production operations (Chriss 2002). Black shales are the source rocks for petroleum trapped within Uranium deposits (IAEA 2009).
According to current ideas kerogen† is the organic constituent of sedimentary materials that is associated with petroleum formation. Kerogen is considered by petroleum geologists as being of two different varieties: humic kerogen associated with poor oil sources and sapropelic‡ kerogen, related to subaqueous sediments and associated with rich oil sources. Oil and gas is formed by the thermal cracking of organic matter (kerogen) trapped in sedimentary rock.
Two hypotheses regarding NORM in E&P production operations need to be considered. The first hypothesis is that NORM is produced by locally high U and Th concentrations in the reservoir rocks. If this is generally true, NORM scale will be largely controlled by the geological formation and lithology. The second hypothesis is that NORM is released from ordinary geological media during normal geological processes. If this is generally true, the potential for NORM scale
precipitation may be predicted largely from basin setting and history.
A worldwide survey comprising a comprehensive review and detailed analysis of reported NORM activity in oilfield scales has now determined which of these hypotheses prevails. For the first time management will now have the ability to predict the magnitude of NORM in E&P facilities worldwide.