Comparative Study On Tight Sandstone Reservior Of The Xu6 Member In Guang'an And The Chang6 Reservior In Banqiao-Heshui Area

Tight sandstone reservoir is the important exploration field of unconventional natural reservoir in the word.Tight sandstone reservoir is abundant in China.Sichuan basin and ordos basin are all important tight sandstone development zones in China.The xu6 member in Guang'an and the chang6 reservior in Banqiao-Heshui are tight sandstone reservoir.According to the core,casting thin sections,scanning electron microscopy,physical property and mercury injection data on the basis of area reservoir petrology characteristics,and through the physical properties and pore structure characteristics,comparative research,explore in different areas,different sedimentary background,this paper expounds the tight sandstone reservoir what the similarities and differences are in terms of reservoir development.This paper finds the similarities and differences of reservoir,analysis of the main reasons for the formation of tight reservoir through two aspects of sedimentary and diagenetic.The research reveals the formation of tight sandstone reservoir,the main results and understanding as follows:(1)Because of the different sedimentary background and sedimentary facies,there is a big difference in petrology,mineral composition,filler content,sandstone grain size,sorting and roundness between the xu6 member in guang'an and the chang6 reservior in Banqiao-Heshui.(2)It also has big differences among the reservoir properties,pore type and pore structure.The analysis shows that it is mainly caused by primary permeability and diagenesis.(3)Primary permeability and depositional combination are greatly influenced on the characteristics of the reservoir.The diagenesis intensity is also influenced indirectly.(4)In diagenetic process,because of the effects of compaction and cementation,large number of pores loses,and forms tight reservoir.Secondary porosity caused by dissolution make little sense to tight reservoir,but it can improve the reservoir property and change porosity type.(5)The study of the effect of reservoir characteristics,sedimentation and diagenesis shows that,with different area and sedimentary background,the cause of the formation of the reservoir is consistent,material basis is provided by sedimentation,diagenesis is the key to forming a tight reservoir,strong compaction and cementation result in a large loss of reservoir porosity,making the reservoir tight.Dissolution is too weak to change the density of the reservoir.In a word,the reservoir is controlled by sedimentary and diagenetic together.