平湖地区ZST构造X井平湖组储层特征研究

Reservoir characteristics of Pinghu Formation in X well in ZST structure of Pinghu area

以平湖地区ZST构造X井区有限的钻井资料为基础,利用岩石铸体薄片、扫描电镜、X-衍射等测试技术手段,对该井区平湖组的岩石学特征、粒度、储层物性等方面开展了系统研究。研究揭示:该储层的岩石类型主要为长石岩屑砂岩,属中孔中渗砂岩储层。平湖组储层物性受沉积环境和成岩作用的双重影响。沉积环境控制储层物性,潮间带和潮下带发育的潮道砂、砂坪是较好的储层;成岩作用对储层物性优劣起主导作用,胶结作用导致储层物性变差,溶蚀作用(长石溶蚀作用)改善了本井平湖组的储层物性。

ZST structure, in south of Pinghu area, is a NNW trending reverse dragging semi-anticline occurred in Pinghu fault subsiding block. Existing research has revealed that the sandstone of Pinghu Formation has favorable reservoir-forming conditions and reservoir area is controlled by the gulf background such as gulf-wad depositional system in intertidal zone and subtidal zone. But because of boreholes are few, the cognition is weak now. Based on vast borehole and core data, the reservoir is composed of lithic arkoses, which belongs to middle porosity and middle permeability sandstone reservoir. Casting thin sections, scanning electron microscope and X ray diffraction show that reservoir properties of Pinghu Formation is influenced by sedimentary environment and diagenesis. Reservoir properties are controlled by the sedimentary environment. Channel facies and sand flat of intertidal zone and subtidal zone are good reservoirs. The diagenesis plays a critical role in the quality of reservoir properties. Cementation breaks the reservoir properties, while dissolution improves it.