Formation water geochemistry according to the integrated study of the core and cuttings samples of the Leskinskaya Well (West Taimyr potential oil and gas bearing area)

Introduction. The West Taimyr potential oil and gas bearing area is one of the major Arctic exploration clusters of Gazprom Neft. The lack of comprehensive research work in this area, including hydrogeological studies, does not allow to reliably evaluate the hydrocarbon resource potential.
Aim. Analysis of hydrogeochemical research materials obtained within the Leskinskaya well drilling stage, which is a low-studied but the high potential productive region of the West Taimyr.
Materials and methods. We used an integrated solution for the complex characterization of formation water using both core and cuttings samples. The workflow includes the free and bound water content measurements by the evaporation method (EM) with isotopic analysis (δ18O and δD) of the released water and the formation of water salinity estimation using a modified method of aqueous extracts. The results of the cutting using core data were accurately verified by direct analysis of the formation water composition.
Results. For the first time, a chemical composition of the formation waters of the Mesozoic-Paleozoic deposits along the Leskinskaya well of the West Taimyr potential oil and gas bearing area was obtained.
Conclusion. The complex interpretation of the obtained results shows that there is direct hydrogeochemical zoning with the formation water total salinity increasing down the section. The upper part of the section (up to the Lower Devonian) is washed out by the surface infiltration waters. The deeper part of the section has low hydrogeological connectivity with the overlying aquifers and includes the ancient relict waters of varying degrees of metamorphization stage and with a heavier isotopic composition.

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