The Relationship Between The Characters Of Reef-banks Facies Of Changxing Formation And Taphrogenesis In Tongjiang Tiechanghe

Reef-banks facies of The Upper Permian Changxing Formation are widely developed in the northeast Sichuan Basin,and its'reservoirs are important reservoir space.Therefore,the research to the reef-banks facies'distribution and characteristics was great significance.As is known to all,the distribution of sedimentary facies is controlled by tectonic movement.Which through the research of the relationship between the distribution and characteristics of reef-banks facies and Emei Taphrogenesis can better guide the oil and gas exploration.The Tiechanghe organic reefs developed in the Upper Permian Changxing Formation are another important representative of platform edge reefs in northeast Sichuan basin. By studying the measurement of 4 outcrop and their detailed indoor examining, this paper finds that the reefs here are not just some isolated reefs like Linchang, and Jiaoshutang, but a united Changxing reef-bank complex. The Changxing Formation is mainly made up by platform edge reefs and platform edge shallow facies, and three upwards vertical cycles reef-bank complex. The main reef-building organism of the organic reefs is sponge, taking a percentage of about 20-50%; fringing reef organism are algae, foraminifer, fusulinida and other categories,and its primary reef-building process is baffling.Although the development scale of a single reef is small,but the subfacies in the reef complex could be easily distinguished. The reef base contains many bioclasts and mostly composed of gray middle-heavy bedded bioclastic grainstone.In the reef core,the form of sponge is intact,which is 5-8cm long,3-6cm width.Sponge upright growth and some recumbent growth.the reef cover and reef top mostly composed of thin-middle bioclastic grainstone and fine dolomite.The reef flank had some flint nodules.The interreef deposits a thick bioclastic bank. Reservoir lithology is mainly made of reef limestones and bioclastic grainstones , with low level dolomitization. Holes are rich, but many were filled with calcite crystals.The reservoir suffered many kinds of diagenesis,including compaction,pressolution,micritization,cementation,recrystallization,dolomitization, dissolution and cataclasis,which are constructional to the reservoir is dissolution,dolomitization and cataclasis.Throhgh the research of the character of reef–banks to Puguang,Huanglong and Panlongdong area in the eastern of Kaijiang– Liangping aulacogen,it is revealed that The Emei taphrogenesis does control the distribution of reef-banks facies in the northeast of Sichuan Basin,and detailed analyse the characters of reef–banks in each region,and finger that the carbonate platform in the eastern of Kaijiang–Liangping aulacogen sloped towards north and east,overall,the northern and western low-lying,the southern and eastern is high terrain.