CONTENT OF RARE-EARTH ELEMENTS IN GROUNDWATERS OF UPPER JURASSIC SEDIMENTS OF THE VERKH-TARSK OIL FIELD (WESTERN SIBERIA)

The results of the analysis of rare earth elements distribution in groundwater of J1 reservoir of the Verkh-Tarka oil field are reported for the first time. It was established that groundwater with Cl Na composition are predominate, with a value of total mineralization from 24.7 up to 48.9 g/dm3. The content of REE ranges from 3.72 to 30.49 µg/dm3 with an average of 13.61 µg/dm3. The highest concentrations are observed (µg/dm3) in La (up to 20.8), Eu (up to 7.9), Gd (up to 1.8) and Dy (up to 0.65). The level of dissolved REE is determined by their distribution in the water-bearing sandstones. Migration of rare-earth elements is carried out in the form of free ions and hydroxide complexes.

The rare-earth elements distribution in the Bazhenov shales

The rare-earth elements and yttrium (REY) distribution data with depth in the Bazhenov formation are given for the case of the one well in the Nizhnevartovsk arch of the Western Siberia, Russian Federation. According to the correlation analysis, it was found that REY (mainly LREE) is concentrated in apatite more than in clays or plagioclase, while HREE is preferably accumulated in clay minerals. It was estimated that the water extracts from the Bazhenov formation contain REY up to 0.014 ppb, while LREE is contained in 3.6 times more than HREE. An attempt to estimate the REY content in the pore water of the Bazhenov formation was made using water extract composition data.