Analysis of sedimentary facies and reservoir characteristics of Middle-Lower Ordovician Yijianfang Formation in Tuofutai area,Tahe oilfield,Xinjiang,China

This research mainly covers the property core observation,the casting thin sections observation and identification and the analysis of sedimentary facies,reservoir space types,reservoir physical types by characteristic of lithologic,geophysics and organic sediment about Ordovician Yijianfang Formation in the Tuofutai area of Tahe(River Tarim) oilfield.The results show that in the research area there exists wide mesa faces(including intraplatform shallow sub-facies,intrashallow sea sub-facies and the second depression zone sub-facies).The pore space consists of intergranular dissolved pore,intragranular dissolved pore,moldic pore and fracture.By further studying the different grouping types,the reservoir space can be divided into four types including vuggy-fractured reservoir,fractured-vuggy reservoir,fractured reservoir and crack-dissolved pore reservoir.For the relatively lower degree of porosity and penetration rate of the carbonate rock reservoir,it is hard to form effective reservoir spaces.