鄂尔多斯盆地彭阳—泾川地区长8 1小层沉积储层特征

The characteristics ofsedimentary facies and reservoir of the Chang 81 member in Pengyang-Jingchuan Area,Ordos Basin

利用钻井岩心中沉积构造、古生物标志等对长81小层的沉积相进行分析,利用核磁共振、压汞、扫描电镜、铸体薄片等方法对长81储层进行研究。结果表明,彭阳—泾川地区主要发育三角洲前缘亚相,仅在西南缘发育三角洲平原亚相,发育4支北东—南西向展布的水下分流河道,水下分流河道砂体为主要储集砂体。砂岩类型以灰色—灰绿色、细—粉细岩屑长石砂岩和长石岩屑砂岩为主,储集空间以粒间孔和溶蚀孔为主,孔隙类型主要是中—大孔隙,喉道主要为细喉和微细喉。长81储层处于晚成岩A期,压实-压溶作用导致原生孔隙减少23.8%,胶结作用使孔隙度减少27.35%,溶蚀作用增加的孔隙面孔率为1.23%。研究后认为,沉积相、成岩作用是控制研究区储层物性的重要因素。

Using the sedimentary structures and paleo-biotic features obtained from the drilling core to analyze the characteristics of sedimentary facies and reservoir of Chang 81 member in study area;using nuclear magnetic resonance,high pressure Hg injection,scan electron microscope,casting lamella and other methods to analyze the characteristics of chang 81 reservoir.The investigation finds the chang 81 member of the Pengyang-Jingchuan Area mainly developed the braided river delta frontal subfacies,and the delta plain facies only developed in the southwest of study area,and the four underwater distributary channels are almost distributed from NE to SW,the channel sand dominated the advantage space.The Chang 81 member sandstone are mainly gray,green-grayish lithic feldspathic sandstone and feldspar lithic sandstone,the intergranular pore and dissolved hole are main pore space of Chang 81 reservoir,and the pore type are mainly meso-and macroporosities,intergranular pore throat types are mainly micro throat and micro fine throa pore throat.The reservoir rocks are now in stage A of late diagenesis.Due to the compaction and presolution,cementation,the decrease of the primary sandstone porosity of each diagenesis are 23.8%and 27.35%;because of dissolution,the rate of face porosity slightly increased is 1.23%.After the research,it is believed that deposition and diagenesis are the main factors influencing physical properties in study area.