陕北斜坡延长统低渗储集层成岩相研究

鄂尔多斯盆地三叠系延长统储集层具有低渗、特低渗性质 ,强烈的成岩胶结作用是形成低渗的主要原因。不同的沉积微相其胶结类型不同 ,从而导致酸性水溶蚀次生孔隙所发育的程度迥异。通过沉积微相分析、以及大量岩石显微薄片的观察 ,对盆地东北部志靖三角洲长 6储集层的成岩相总结为 8种类型 ,并分析了 3种沉积充填类型 (序列 )与成岩相的关系。第Ⅰ种充填类型为叠置水下分流河道 ,主要发育绿泥石 浊沸石胶结相 ,在叠置水下分流河道靠近湖盆一侧 ,主要发育浊沸石 长石溶蚀相 ;第Ⅱ种充填类型为孤立水下分流河道 ,主要发育绿泥石 方解石胶结相 ;第Ⅲ种充填类型为水下分流河道间洼地微相 ,主要发育钙质 泥质胶结相。在上述分析的基础上 ,对长 6 1 2和长6 2 1两个重点含油层位储集层进行了成岩相的平面预测 ,指出志靖、安塞三角洲有利沉积相带及有利成岩相应向湖区延伸。图 4参 4

Diagenesis and diagenetic facies studies for Yanchang Formation of the Triassic in Ordos basin

The reservoirs of Yanchang Formation of the Upper Triassic in Ordos basin are low and super permeability reservoirs, which were formed by vigorous diagenesis. Generally, different sedimentary microfacies developed different types of cementation that controlled distribution of secondary pore dissolved by acid water solution. Through studying sedimentary microfacies of Chang 6 reservoir and analyzing about 500 thin sections, diagenetic facies of Chang 6 reservoir are classified as eight types. For the above mentioned study and analysis, the authors discuss the relation of sedimentary facies and cementation types. Finally, the authors predict the distribution of diagenetic facies for Chang 6 2 1 Chang 6 1 2 reservoirs and obtain a result that the favorable sedimentary facies tract and favorable diagenetic facies of Zhijing and Ansai delta may extend towards lake area.