鄂尔多斯盆地镇原地区长8油层组低渗透储层特征

Low permeability reservoir characteristics of Chang 8 oil reservoir set in Zhenyuan area, Ordos Basin

据岩心、铸体薄片、扫描电镜和常规物性等资料,结合测井解释成果,对鄂尔多斯盆地镇原地区长8油层组砂岩储层特征进行了研究。结果表明:长8油层组砂岩储层曾遭受酸性介质的改造,次生孔隙发育;储集空间以剩余原生粒间孔、粒间溶孔和微裂缝为主,黏土矿物晶间微孔对储层物性也有贡献;储层发育受沉积相、碎屑组分、成岩和构造作用共同影响,其中沉积微相影响储层的空间展布;碎屑组分和粒度与储层物性具有直接关系;成岩作用对储层物性的影响有利有弊,压实和胶结作用可使原生孔隙大部分丧失,而溶蚀作用形成的次生孔隙可大幅度提高储层的孔、渗性,为形成优质储层的关键。

Based on core observation, cast thin sections, scanning electron microscopy and physical properties, combined with well logging interpretation, this paper studied the reservoir characteristics of Chang 8 oil reservoir set in Zhenyuan area, Ordos Basin. The result shows that the reservoir suffered acidic alteration with secondary pores developed. The reservoir space is dominated by remaining primary intergranular pores, intergranular dissolved pores and microcracks. Intercrystalline pores between clay minerals have also a little contribution. The reservoirs are controlled by sedimentary facies, detrital composition, diagenesis and tectonism. The favorable microfacies controlled the spatial distribution of the reservoirs. The clastic composition and grain size are directly related to physical properties. The diagenesis has both good and bad effects. The compaction and cementation made the majority of primary pores lost. The dissolution formed secondary pores which greatly improved the porosity and permeability, and they are crucial to the high quality reservoirs.