| The Ordos Basin is a polycyclic superposition basin.It is the largest terrace sedimentary basin in China which possesses abundant oil and gas resources.It is an important resource supply area in China.The aim is to study the sedimentary facies and their relationship with oil and gas accumulation in this area.The relationship of sedimentary facies with oil and gas accumulation is studied and summarized from data collected.We collected abundant data of geology,drilling,logging,well testing,regional geological setting,sedimentary microfacies and sandstone distribution,reservoir characteristics of Yan 9.Used the marker formation in the study area,combined with sedimentary cycle and the principle of the thickness of strata,according to the traditional division method,this study divided Yan 9 into two sections: Yan 91 and Yan 92.Yan 9 belongs to meandering river facies.The sand body in channel is the main reservoir.The lithology is mainly feldspathic sandstone.The clastic particles is medium rounded,well sorted.Contact relationship is line contact.Rocke are mainly siliceous and calcareous cemented.In the study area Yan 9 reservoir has entered the late diagenesis stage.Main sedimentary effect are compaction,pressolution,cementation and dissolution effect.The sedimentary facies in the study area can be divided into several types of microfacies,the riverbed detainment sedimentation is the main reservoir.Through the analysis of the relationship of sedimentary facies and hydrocarbon enrichment,it is consider that the thick sand layer at the bottom of the yan 10 is the pressure relief port of the lower excess pressure,that is the main channel of Lower oil and gas migrate to yanan group.Yan 9 reservoir has mainly affected by sedimentary facies,mainly gathered in the sand body thickness,these areas are the advantage of regional river development.Oil and gas are rich in the riverbed detainment sedimentation in the lower of river subfacies. |
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