玛湖凹陷东斜坡区下乌尔禾组砂砾岩储层孔隙形成机理及优势储层成因分析

以宏观沉积特征描述为基础,利用岩石薄片、铸体薄片、扫描电镜、X衍射、压汞和物性资料,对玛东斜坡区下乌尔禾组砂砾岩储层孔隙类型及成因进行研究;发现主要发育三种孔隙类型,剩余粒间孔、粒间浊沸石溶孔和泥质杂基收缩孔。剩余粒间孔因颗粒的支撑而形成,与黏土膜对孔隙的保护作用有关;泥质杂基收缩孔因伊/蒙混层矿物向伊利石转化而形成;粒间浊沸石溶孔受源于二叠系风城组烃源岩的有机酸溶蚀而形成。玛东2井区处于扇三角洲内前缘,以辫状河道砂砾岩沉积为主,主要发育剩余粒间孔和浊沸石溶孔,且以剩余粒间孔为主;夏盐2井区地处扇三角洲外前缘,以水下分流河道砂砾岩和河口坝砂岩沉积为主,主要发育浊沸石溶孔。扇三角洲前缘水下分流河道砂砾岩,可以提供碱性的高孔渗的开放性环境,有利于浊沸石的早期形成和后期溶蚀,是有利的储层孔隙发育区。

Pore formation mechanism and Genesis of advantage reservoir of Permian Lower Urho Formation glutenite reservoir in the Madong Area,Junggar Basion

Based on macroscopic sedimentary characterization combined with rock flakes, cast thin, scanning electron microscopy, X-ray diffraction, mercury and physical property data. We conduct research on Pore formation mechanism of glutenite reservoir of Permian Lower Urho Formation,and find that there are three major void in the area,they are the remaining intergranular pore, laumontite dissolution pores and muddy shrinkage holes. The remaining intergranular pore formed because of the particulate support by gravel, related to Protective effect of Clay films. muddy shrinkage holes formed because of the transformation from illite / smectite to illite. laumontite dissolution pores formed because of alkali feldspar dissolution by Organic acids from the Fengcheng Formation source rocks. Madong 2 well zone is within the fan delta front, Mainly to braided river sediments glutenite. The main pore types are the remaining intergranular pore and laumontite dissolution pores. Xiayan 2 well zone is within the Internal fan delta front, Mainly to Underwater distributary channel glutenite and Mouth bar sandstone. The main pore type is laumontite dissolution pores. Underwater distributary channel glutenite of the fan delta front which is beneficial for laumontite formed early and late dissolution is favorable reservoir porosity development zones.