Main controlling factors for the enrichment of oil and gas in deep tight sandstone in the Qiudong Sub-sag of the Turpan-Hami Basin
The Qiudong Sub-sag is the replacement field for oil and gas exploration in the deep tight sandstone of the Taibei Sag in the Turpan-Hami Basin.In view of the problems such as large differences in oil and gas production and water content in the test production of multiple horizontal wells in the Qiudong Sub-sag and unknown factors for the horizontal and vertical differential enrichment of deep tight oil and gas,based on exploration and development practice,this study systematically investigates the main controlling factors for the enrichment of oil and gas in tight sandstone of the Sangonghe Formation in the Qiudong Sub-sag of the Taibei Sag with seismic,geochemical,analytical testing,and other data.The results show the followings.①The tight oil and gas of the Sangonghe Formation originate from the coal-measure source rocks of the Badaowan Formation and the lacustrine mudstone of the top of the Sangonghe Formation.The lacustrine mudstone has a stable plane distribution and a thickness of 20-40 m.It is source rocks and also a set of good regional caprocks,forming a sandwich-like source-reservoir-cap(source)combination with the coal-measure source rocks of the Badaowan Formation and the braided river delta channel sand bodies of the Sangonghe Formation,with good reservoir-forming conditions.② The Sangonghe Formation fault-fracture system provides favorable channels for vertical and lateral migration of deep oil and gas.At the same time,it effectively improves the physical properties of deep tight sandstone reservoirs and is a key factor in the enrichment of oil and gas in deep tight sandstone.③ The mudstone area at the top of the Sangonghe Formation is stably developed,and the lithology is relatively pure,which provides good caprock conditions for the enrichment and preservation of oil and gas under it in the Sangonghe Formation reservoir.④ The fault-fracture-cap system is developed in the Sangonghe Formation of the proximal slope of the Qiudong Sub-sag,and the physical properties of reservoirs are relatively good,making it a favorable area for searching for oil and gas reservoirs in deep tight sandstone.This finding has important guiding significance for the exploration of oil and gas in deep tight sandstone in the Turpan-Hami Basin.
deep layertight sandstonefault-fracture-capenrichment factorsSangonghe FormationTurpan-Hami BasinQiudong Sub-sag
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