高邮凹陷永安地区戴南组一段储层特征及主控因素

通过岩心、铸体薄片、扫描电镜、物性分析和孔隙图像分析等资料,对高邮凹陷永安地区戴南组一段砂岩储层特征进行了系统分析,从沉积和成岩两方面对储层物性主控因素进行了研究。研究结果表明:岩石类型为长石岩屑砂岩,成分成熟度较低,粒度偏细,分选中等偏差; 储层物性以低孔低渗为主中孔中渗为辅,孔隙类型有粒间孔、粒间溶孔、粒内溶孔和铸模孔,平均孔径为37.53 μm,喉道主要为可变端面的收缩部分,其次为片状和弯片状喉道,平均喉道半径为10.25 μm,孔喉配位数主要为3,分选性好。沉积作用是高邮凹陷永安地区戴南组一段砂岩储层物性主控因素之一,水动力强分选程度高的沉积环境形成的砂岩粒度大分选好,储层物性好; 不同的成岩作用类型对储层物性具有不同的控制作用,压实和胶结作用导致储层孔隙空间变小,物性变差,而溶蚀作用形成次生孔隙空间,储层物性得到改善,在2 500～2 700 m和2 850～2 950 m处形成了明显的次生孔隙发育带。

Reservoir characteristics and its main controlling factors of Dainan1 formation in Yongan Area, Gaoyou sag

The sandstone reservoir characteristics of Dainan 1 Formation of Yongan area in Gaoyou sag are analyzed based on the data of core,casting film,electron microscope scanning,poroperm analysis and pore image analysis,and the main controlling factors of the reservoir quality are studies from the aspects of sedimentation and diagenesis.The results show that the sandstones are mainly feldspathic litharenite with low compositional maturation,fine grain,and medium-bad sorting degree.The reservoirs are mainly of low porosity and low permeability,and supplemented of medium porosity and medium permeability.The pores are mainly intergranular pores,intergranular dissolved pores,intragranular dissolved pores and moldic pore,with the average pore diameter of 37.53 μm.The throats are mainly the shrink parts of the feasible end faces,then the laminated throat and the curved lamellar throat,with the average throat radius of 10.25 μm,throat pore coordination number of 3,and good sorting.The research indicates that the sedimentary factor is one of the main controlling factors of the sandstone reservoir quality of Dainan 1 Formation of Yongan area in Gaoyou sag,and the sandstone formed in the sedimentary environment with high hydrodynamic intensity has good reservoir quality with large grain and good sorting.Different kinds of diagenesis have different effects on reservoir quality.Compaction and cementation make the reservoir quality become worse,while the dissolution make the reservoir quality become better by producing secondary porosity.The secondary porosity zones are obvious in the depth of 2 500～2 700 and 2 850～2 950 m.