子洲-清涧地区山西组山2_3段储层物性影响因素分析

Influence factors of Shan 2_3 reservoir property of Zizhou-Qingjian area

利用铸体薄片、扫描电镜、压汞分析及岩心观察和测井等各种基础资料,对鄂尔多斯盆地子洲-清涧地区山2_3储层物性特征及影响因素进行分析。研究结果:子洲-清涧地区山西组山2_3渗透率和孔隙度具有明显的正相关特征,储层物性主要受控于沉积微相、岩石类型、粒度以及成岩作用。水下分流河道砂体孔隙度、渗透率相对较高,河口坝席状砂次之,分流间湾较差;石英砂岩物性普遍好于岩屑石英砂岩,岩屑砂岩则相对较差;砂岩的粒度越大,储层物性越好,粗砂岩、巨-粗砂岩的物性要明显好于中-粗砂岩、粗-中砂岩、细-中砂岩。成岩作用中压实作用和胶结作用是储层物性变差的主要原因,溶蚀作用是一种对储层有利的建设性成岩作用,有利于产生大量次生孔隙,成为碎屑岩储层主要储集空间。

The physical property and influential elements of Shan 23member of Zizhou-Qingjian area in Ordos Basin were studied by analysis of the cast slices, scanning electron microscope, porosity and per- meability, log interpretation and mercury injection test. The results show that： the porosity and permeabil- ity at Shan 23member of Zizhou-Qingjian area in Ordos Basin has a significant positive correlation. Res- ervoir properties controlled by sedimentary microfacies, rock type, grain size and diagenesis. Underwater distributary channel has relatively high porosity and permeability, underwater mouth bar and sheet sand are followed, and underwater natural levee is relatively poor. The physical properties of quartz sandstones is generally better than that of lithic quartz sandstones, and lithic sandstones is relatively poor. In gener- al, physical property parameters decline with the change of grain size from gravel through coarse sand and medium sand to fine sand. The rocks with inter granular, inter-crystalline porosity and solution po- rosity have good reservoir physical property, but then, the rocks with micro-porosity have poorer physical property. Diagenesis of the study area is also an important influence factor. Decrease of sandstone porosi- ty is mainly caused by compaction and the cementation. The dissolution is a diagenesis that can produce a large number of secondary porosity and constitute the main reservoir space of clastic rocks, which make the performance of a reservoir better.