Source Rock Potential and Petroleum Systems of the Triassic and Paleozoic Successions of the Hayan Block, Central Syrian Palmyrides

摘要

Recent INA Oil Company discoveries in the central Syrian Palmyrides (Hayan Block) accentuate the Triassic Kurrachine Dolomite Formation as a major play for hydrocarbon generation and accumulation. Previously Triassic and especially Paleozoic source rocks and Petroleum Systems were not been studied in more detail. The evaporate/carbonate succession, and their associated lithofacies of the Triassic Kurrachine Dolomite Formation, become increasingly attractive exploration targets. The characteristic play definition is shown for the Hayan Block based on three defined elements: petroleum charge systems, the source-reservoir formation characteristics and the trap-seal type. Three Petroleum Systems of the Paleozoic, Triassic and Cretaceous/ Paleogene successions were recognized. It was presumed that hydrocarbon generation and migration (accumulated in the Triassic reservoirs) occurred from deeper Middle-Lower Paleozoic 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, geochemical analyses and 3D seismic show a much larger volume of mature source rocks than that predicted purely from geochemical analyses. A calculated volumetric characteristic of Triassic source rocks indicates their high hydrocarbon generating capability. Intensive tectonic activity formed fractured zones as favorable 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 Systems in the area of the Hayan Block. Triassic Petroleum System incorporates the Triassic Kurrachine Dolomite, Amanus Shale Formations and the Permian Amanus Sand Formation. Paleozoic succession is rather (dry) gas prone or being overmature, while Cretaceous/Paleogene Petroleum System is immature in this area and is capable to produce only heavy oil, thus, it is not evaluated in more detail.