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Petroleum Geological Characteristics and Exploration Potential of Paleozoic Clastic Rock Stratum Series in Qatar

Rao Yong, Du Xiangdong, Yu Shui, Huang Xingwen, Sun Pengchao   

  1. Overseas Evaluation Center of CNOOC Research Institute
  • Published:2015-05-20

Abstract: Tectonic and sedimentary evolution of the Arabian Plate provided favorable petroleum conditions for Paleozoic hydrocarbon accumulations in Qatar. The analysis shows that a set of high-quality source rock (graptolite hot shale) developed at the bottom of the Silurian System in Qatar, with development of two sets of clastic rock reservoir-cap assemblage. The reservoirs are mainly fluvial-delta facies sandstone with the buried depth usually exceeding 3600 meters. Generally speaking, the reservoir rock is relatively tight and mainly of mid to low porosity and low permeability. However, the sweet spots of the reservoirs might develop partially in the region, with a good productivity. The types of Paleozoic traps are mainly anticlines, faulted anticlines, updip pinchout lithologic traps and stratigraphic traps in connection with unconformity. There are three hydrocarbon accumulation patterns. The main pattern is migration and accumulation based on transportation through vertical faults and generated in the lower and stored in the upper part. Hercynian tectonic compression and salt uplift have a critical effect on development of Paleozoic traps, which were shaped mainly in Late Permian – Late Triassic, earlier than the hydrocarbon expulsion period of Silurian source rock. The conditions for accumulations were matched desirably. The clastic rock stratum series in Qatar has highquality source rock as its materials basis, favorable reservoir-cap assemblages, favorable areas for accumulation of structural traps and excellent conditions for hydrocarbon accumulations. The stratum series has a great potential for exploration thanks to low extent of exploration. The main favorable areas for potential exploration are the flanks of Qatar Uplift and the Southern Gulf Salt Basin in the eastern part of the country,