玛南斜坡下乌尔禾组砾岩储层特征及主控因素

Characteristics and Controlling Factors of Glutenite Reservoir in Permian Lower Urho Formation in the South Slope of the Mahu Sag

准噶尔盆地玛湖凹陷南斜坡二叠系下乌尔禾组具有良好的勘探前景,为明确该区储层特征及主控因素,通过岩芯观察、铸体薄片、扫描电镜及储层物性等手段,对二叠系下乌尔禾组砾岩储层特征及主控因素进行了研究。结果表明,下乌尔禾组储层岩石类型主要为岩屑砂岩,胶结类型以泥质、沸石胶结为主,结构及成分成熟度较低。储层储集空间类型多样,以剩余粒间孔、火山物质溶孔及沸石溶孔为主。储层物性主要受沉积作用、成岩作用及构造作用共同影响。其中,优质储层受沉积相带控制作用明显,以牵引流为主的扇三角洲前缘水下分流河道是最有利的沉积相带,其次为扇三角洲平原水上分流河道;成岩作用主要有压实作用、胶结作用和溶蚀作用,其中,压实减孔损失量平均为24.0%,胶结减孔量为4.9%,溶蚀作用以浊沸石溶蚀为主,产生的次生溶蚀孔隙对储层物性具有明显的改善作用。构造破裂作用对储层物性也具有重要的改造作用。

Good prospects of exploration of the Permian Lower Uhro Formation on the south slope of Mahu Sag in Juggar Basin.Based on the core observation,the casting of the thin sections,SEM,as well as the analysis of reservoir physical properties,the characteristics and controlling factors of Lower Urho Formation have been researched.The results indicate that the type of reservoir rock in the Permian Lower Uhro Formation is mainly debris sandstone with muddy and zeolite cementation,and reservoir has lower maturity of structure and composition.There are various of pores of reservoir space,mainly the residual intergranular pores,volcanic material pores and zeolite pores.Influencing factors on physical properties of reservoirs are sedimentation,diagenesis and tectonism.The reservoir is controlled by sedimentary facies belt.The under-water distributary channel on the leading edge of the fan Delta is the most favorable sedimentary facies belt,followed by the fan Delta plain water diversion channel.The diagenesis is mainly compaction,cementation and dissolution.Average 24.0%pores are reduced by compaction,and the cementation reduction porosity is 4.9%.The dissolution is mainly turbid zeolite dissolution,and secondary pores formed by dissolution improve physical property.