Warunki hydrochemiczne w dolnopaleozoicznych poziomach perspektywicznych zachodniej części basenu perybałtyckiego

Leszek Bojarski

Abstrakt


HYDROCHEMICAL CONDITIONS IN PERSPECTIVE LOWER PALEOZOIC HORIZONS FROM THE WESTERN OF THE PERIBALTIC BASIN


Summary
Peribaltic syneclize, a depressional unit of the East-European Platform, is also called the Peribaltic basin. This basin opens to the west and passes into the Marginal basin Cambrian deposits from the central and western parts of the Peribaltic basin promise the occurrence of oil fields. In recent years, a remarkable accumulation of bitumens was found in the Żarnowiec area; exploitation of one of the boreholes has just started. Reservoir horizons of the Cambrian are covered here by impermeable series of Ordovician and Silurian strata. Cambrian strata yield brines differing in degrees of metamorphism and mineralization. In general, degree of water mineralization increases from peripheral to central parts of the basin. Values of mineralization vary from 70 to 240 g/l. Variability of water metamorphism appears to be similar. These are chloride-calcic waters with the ratio rNa+ rCl- equaling from 0.65 to 0.35. In the Bartoszyce area (boreholes Br 1 and L 1), brines of the nature of alkali lye were found. Analysis of hydrochemical indices shows that conditions optimal for preservation of bitumen accumulation have existed in the western, deeper part of the Peribaltilc basin. In turn, reservoir horizons of the Cambrian, located outside the range of impermeable cover of Silurian strata, are considered to be less perspective.

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