Lithological and geochemical characteristics of Triassic sediments from the central part of the South Barents depression (Arkticheskaya-1 well)

Abstract

The thickest section of the upper Triassic deposits in the South Barents depression is penetrated by the Arkticheskaya-1 well. Core samples from this well were analysed for lithology, palaeontology and geochemistry. Different environments of deposition were interpreted on the basis of these analyses. Continental and coastal facies dominate, but some short-term sea ingressions were also identified. The geochemical data include qualitative and quantitative characteristics of the organic matter and bitumen. Maturity-related changes are described, and the zone of optimum conditions for the generation of hydrocarbons is determined. Ladinian and Carnian deposits are found to be the major source of hydrocarbon-rich rocks: they are dominated by humic kerogens, and are of a maturity within the 3990–4515-m oil window. Triassic deposits of the Barents Sea region represent different depositional facies; consequently, a wide variety of lithologies are present. An integrated study of the sedimentary rocks provides information on the textural and mineral composition, organic geochemical parameters, the structural features and the fossil content to interpret their depositional environments, and their oil or gas potential.