SR-XFA of uranium-containing materials. A case of Bazhenov formation rocks exploration

When an X-ray fluorescent analysis (XFA) is carried out, errors are possible because fluorescent K-lines of “light” elements and L-lines of some “dark” elements can overlap in energy domain. With certain contents of these elements and insufficient resolution of the spectrometer, this leads to considerable errors of determination. An example is the overlapping of a large number of uranium (U) L-lines and Rb, Nb, Mo K-lines. In this paper a procedure is suggested to correct such overlapping. It was tested on uranium-containing rock samples. These samples represent the oil-producing Bazhenov rock formation, which is characterized by organic matter accumulated in abundance and accompanied by “organophile” elements, including U. The procedure is based on scanning the energy of initial exciting X-radiation. This may be regarded advisable only in the XFA versions that use synchrotron radiation — SR-XFA. As a result of this investigation, geochemical characteristics of the Bazhenov formation rocks are demonstrated and the efficiency of energy scanning procedure in determining both Rb, Nb, Mo and U contents is revealed (using comparison with other methods). The energy scanning procedure also works in the presence of L-lines of some other dark elements (Pb, Th, etc.) in the energy domain of K-lines of As–Mo.