鄂尔多斯盆地延安地区长4+5油层组致密砂岩储层特征

Characteristics of tight sandstone reservoir of Chang 4+5 oil reservoir set in Yan'an area,Ordos Basin

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0.2～2.0mD,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.