Source Rock generative potential and volumetric characteristics of Kurrachine Dolomite Formation, Hayan Block, central Syrian Palmyrides

摘要

Source rocks from the lower part of the Triassic Kurrachine Dolomite Formation were investigated in order to establish their role in the Petroleum System of the Hayan Block. Recent deep well discoveries accentuate the Triassic Kurrachine Dolomite Formation as a major play for hydrocarbon accumulations. The characteristic play definition is shown for the Hayan Block based on three defined elements: petroleum charge system, the source-reservoir formation characteristics and the trap-seal type. According to geochemical analyses, Triassic source rocks are of good generative potential, but they are not abundant (only thin layers were estimated). It was presumed that hydrocarbon generation and migration occurred from deeper Middle-Lower Palaeozoic Formations. Exploration results show that the generative potential of the Triassic source rocks in the Hayan Block was underestimated. Correlation and calibration of the petrophysical parameters from well logs and geochemical analyses show a much larger volume of mature source rocks than that predicted purely from geochemical analyses. The Kurrachine Dolomite Formation resistivity of 20 Ωm is typical of the area, and it represents the threshold value (Net Pay cutoff criteria) between immature and mature source rocks. Net Pay thickness (effective thickness), of mature and generative source rock intervals, exceeds more than 150 m in some wells. A calculated volumetric characteristic of source rocks indicates their high hydrocarbon generating capability. Intensive tectonic activity formed fractured zones as favourable reservoir rocks, so in some areas, practically no or very short migration pathways exist. Expelled hydrocarbons (within explored area) have not been accumulated into discrete reservoirs, thus the system is generating oil in situ. The results accentuate the existence of a key Triassic Petroleum System in the area of the Hayan Block. This Petroleum System incorporates the Triassic Kurrachine Dolomite, Amanus Shale Formations and the Permian Amanus Sand Formation.