盐定地区长8油层组成岩作用特征及影响因素

鄂尔多斯盆地长8油层组是受成岩作用影响的典型的低孔低渗储层，通过对研究区砂岩扫描电镜、铸体薄片及物性资料的分析，长8油层组岩性主要为长石砂岩、岩屑长石砂岩，其次是长石岩屑砂岩。储集空间以原生粒间孔和次生溶孔为主。成岩作用类型包括压实-压溶作用、胶结作用、溶蚀作用、交代和重结晶作用；其中绿泥石胶结和长石、浊沸石溶蚀能有效的改善孔隙，有利于储层发育，而压实作用和碳酸盐胶结则使原生孔隙减小和储集层致密。成岩作用更受到原始沉积物组分，沉积环境，结构及孔隙间的流体性质，埋藏作用等多种因素控制；而这些因素又与大地构造背景联系紧密。

Diagenesis and its influencing factors of the Chang 8 interval in Ordos Basin Yanding area

The reservoir of Chang8 interval in Ordos basin,controlled by diagenesis,is characterized by low porosity and extraordinary low permeability.Comprehensive analyses have been made on the sedimentary characteristic,property characteristics,rock thin sections,casting thin sections and so on.The results reflect that arkose and lithic arkose is well developed and secondly feldspathic litharenite in the Chang 8 interval of the study area.The reservoir spaces are mainly protogenetic intergranular pore and dissolution pore.The diagenetic types include compaction, pressure solution,cementation,dissolution,metasomatism and recrystallization;in which the chlorite cementation.feldspar dissolution and laumontite dissolution are favorable to improve porosity and reservoir,while the compaction and carbonate cementation are the main contributors to decreasing the intergranular pore and reservoir compaction.Above all,diagenesis is affected by original components of sediments,sedimentary environment,fluid property of stucture and pore,burial metamorphism and so on,which are connected with tectonic background.