Neutron activation analysis of rocks from petroleum wells

The concentrations of major and minor components and trace elements in rocks extracted from seal and collector layers in petroleum wells were determined using instrumental activation analysis with reactor neutrons. A sequence of decaying concentrations for the seals was established: Mn, Ba, Ce, V, Rb, Cr, Co, Al, Sc, As, Th, Cs, Hf, Yb, Tb, Sb, Ta and Lu, in consecutive order. The concentrations of V, As and Sb were greater in rocks from collector layers than those in seals. These results suggest the use of V, As and Sb concentrations as micro-indicators of the presence of petroleum in layers. (author). 8 refs, 3 figs, 2 tabs