根据岩石薄片、铸体薄片、扫描电镜、黏土矿物X 射线衍射、压汞和物性分析等资料，对延安地区长 ₄₊₅ 油层组致密砂岩储层特征进行了研究。结果表明：延安地区长₄₊₅ 油层组储层岩石类型主要为细粒 长石砂岩；孔隙度和渗透率分别为6.0%～10.0% 和0.2～2.0 mD，为典型的致密砂岩储层；储集空间主要 为残余粒间孔，其次为长石和浊沸石溶孔；孔隙结构以小孔细喉型为主，其次为小孔中细喉型和细孔微细 喉型；压实作用及绿泥石、方解石和浊沸石胶结作用是造成储层物性变差的主要因素，而溶蚀作用在一定 程度上改善了储层物性。该研究成果为延安地区长₄₊₅ 油层组致密砂岩油藏滚动勘探开发提供了地质 依据。

According to the data of rock thin section, cast thin section, scanning electron microscope, X diffraction of clay minerals, high pressure mercury and properties analysis, this paper studied the characteristics of tight sandstone reservoir of Chang ₄₊₅ oil reservoir set in Yan’an area. The results show that the rock type of Chang ₄₊₅ sandstone reservoir is mainly fine-grained feldspar sandstone; porosity and permeability range from 6.0% to 10.0% and 0.2 mD to 2.0 mD respectively, and the reservoir belongs to typical tight sandstone reservoir; reservoir space is mainly residual intergranular pores, followed by dissolved pores in feldspar and laumontite; pore structure is dominated by small pore and fine throat type, followed by fine throat and pore tiny throat type; compaction and cementation in chlorite, calcite and laumontite are the main factor for causing poor reservoir properties, and dissolution improves reservoir properties. The results of this study provide a geological basis for rolling exploration and development for Chang ₄₊₅ oil reservoir set in Yan’an area.