河南省南襄盆地泌阳凹陷古近系核桃园组湖相页岩油储集层特征

尽管对南襄盆地泌阳凹陷古近系核桃园组湖相页岩采用大型压裂初产已获高产油气流,但是对该湖相页岩储集层特征尚未进行系统研究。文中应用薄片分析及全岩X衍射分析,结合陆相页岩矿物组成特点,将泌阳凹陷湖相页岩划分为块状泥岩、纹层状黏土质页岩、纹层状粉砂质页岩、纹层状灰质页岩及纹层状云质页岩5种类型。根据页岩岩心样品氩离子抛光扫描电镜分析结果,探讨了研究区湖相页岩的储集特征:(1)主要发育溶蚀孔、晶间孔、粒间孔、构造缝、层间页理缝和微裂缝等储集空间类型;(2)孔隙发育具有各向异性;(3)孔隙以中孔体积为主,微孔次之,孔径平均为4.76nm,有2个峰值区,分别是2~3nm和71nm左右。进一步分析表明,岩石类型控制了储集层的储集空间发育特征,研究区以纹层状灰质页岩的溶蚀孔、晶间孔、有机质孔、层间缝等孔隙最为发育,其亦对页岩油储集最为有利。

Reservoir characteristics of lacustrine shale oil of the Paleogene Hetaoyuan Formation in Biyang sag of Nanxiang Basin,Henan Province

Although high production oil has been achieved from continental shale of the Paleogene Hetaoyuan Formation by using large-scale hydraulic fracturing,less systematical research has been carried out on reservoir characteristics of the lacustrine shale in Biyang sag,Nanxiang Basin. In this paper,by use of thin sections and whole rock X-ray diffraction analyses,combining with the mineral composition feature of continental shale,the lacustrine shale oil in Biyang sag can be divided into massive mudstone,laminated argillaceous shale,laminated silty shale,laminated limestone shale and laminated dolomitic shale. With the photos taken by argon ion polishing high resolution scanning electron microscope(SEM),the reservoir characteristics in study area are concluded:(1)the main reservoir spaces include dissolution pore,intercrystal pore,intergranular pore,fracture,interlayer lamellation seam and macrostructure;(2)the pores are anisotropic;(3)mesopore is prior to micropore in study area,that is,the aperture size ranges from 0.841 to 213.34 nm with average in 4.76 nm, a main peak between 2 to 3nm and the second peak about 71 nm. It is indicated that rock type is the main factor controlling reservoir space development,and the corrosion pore,intercrystal pore,organic pore and interlayer lamellation seam are mainly developed in laminated limestone shale,which are beneficial to the shale oil accumulation.