鄂尔多斯盆地东南缘长3油层组成岩储集相

Study on diagensis reservoir fades of Chang 3 reservoir,Yanchang formation,southeastern margin of Ordos Basin

鄂尔多斯盆地东南缘长3油层组为低孔、特低渗透储层,为明确其成岩储集相类型和优质储层的控制因素,根据铸体薄片、扫描电镜、电子探针、X衍射等资料分析,对其成岩作用特征和成岩储集相类型进行了系统研究。结果表明,鄂尔多斯盆地西南缘长3油层组成岩后生作用复杂多变,破坏性成岩作用主要为机械压实、压溶作用及各类自生矿物胶结作用,溶解作用和破裂作用是储层物性改善的主要途径;长3油层组发育4种类型的成岩储集相,其中浊沸石溶蚀次生—原生孔储集相是最有利的成岩储集相,其分布受沉积相带控制,发育在三角洲平原及前缘截削式分流河道中;浊沸石次生孔隙的发育和沉积砂体的分布特征及是优质储层形成的主控因素。

Combined with the characteristics of diagenetic facies and the structure of pore and the matching relationships of the types of sand body formation,we established the type of diagenetic reservoir facies,and then analyzed the control factor of the high quality res-ervoirs in reservoir Chang 3 of Yanchang formation in the southeastern margin of Ordos hasin,it is also found that the reservoir Chang 3 of Yanchang formation suffered a series of complex and capricious epigenesis in Fuxian exploration area.such as mechan-ical compaction pressure solution and cementation of all kinds of auihigcnic minerals.The epigenesists coufd reduce the porosity until 28.13%,but corrosion might increase the porosity by 3.39%.The cementation of laumontite and the dissolution of lau-montite in Fuxian exploration area were cpigenesist which was different from other exploration area.The original content and corrosion ratio were the main factors influencing the pore of laumontite.The reservoir Chang 3 has 4 types of reservoir facies,a-mong which the reservoir with weak compaction and chlorite rim cementation and laumontite dissoluted secondary pore is the most favorable.The distribution of this diagenesis reservoir facies was controlled by sedimentary facies,which was developed in truncated distributary channel facies of delta plain.The distribution of sedimentary sand bodies and the characteristics of sedimen-tary sand bodies and the development of laumontite dissoluled secondary pore are the main control factors for the high quality reservoirs in reservoir Chang 3 of Yanchang formation in the southeastern margin of Ordos basin.