Correlation of relative boron content with the amount of coal seams as a sign of sedimentation conditions of sediments

Relevance. Establishment of sedimentation parameters of terrigenous reservoirs is an important aspect in predicting new deposits and rational exploitation of hydrocarbon systems. Boron concentration in sandstones serves as an informative indicator of paleosalinity of sedimentary conditions. As a rule, boron accumulation in marine sedimentation regimes is more pronounced compared to its accumulation in continental settings. In contrast, the formation of coal-bearing horizons is predominantly carried out in waterlogged paleolandscapes, where favorable conditions of anaerobic decomposition of organic matter promote peat accumulation. In this relation, the necessity to search for correlations between boron content and the amount of coal seams to reveal the facies of sedimentation is actualized. Aim. To determine the relative boron content and the number of coal interlayers in sandstones of the Tanopchi Formation of one of the Yamal Peninsula fields based on the data of geophysical borehole surveys and to identify correlations between these parameters and sedimentation conditions. Methods. Determination of geochemical parameters based on the data of geophysical well surveys, separation of coal seams based on the data of electrical, radioactive and induction logging methods, separation of electrofacial models using the methodology of V.S. Muromtsev, classical methods of determining the conditions of sedimentation based on the data of core and geophysical well surveys. Results and conclusions. The results of the study indicate high informative significance of relative boron content as an indicator of sedimentation conditions of reservoir rock formation. Determination of boron content normalized to clay content, together with estimation of the number of coal interlayers, allows us to reliably differentiate sedimentary strata of marine and continental genesis. Continental facies conditions show a negative linear regression between the boron content and the number of coal interbeds, which is due to the conditions characteristic of these environments: periodic waterlogging, fluctuations in the acid-alkaline balance, and reduced hydrodynamic activity of formation waters. Marine facies, on the contrary, are characterized by a positive linear relationship between the considered parameters, which can be interpreted in the context of the allochthonous model of coal formation.