准噶尔盆地西北缘乌风地区风城组白云质岩类储层特征及控制因素分析

Reservoir characteristics and controlling factors of dolomitic rocks of Fengcheng Formation in Wufeng area,northwestern margin of Juggar Basin

通过岩心、岩石薄片、扫描电镜等资料,对准噶尔盆地西北缘乌风地区二叠系风城组储层特征及控制因素进行了研究。结果表明:研究区发育的粉砂岩、泥岩和凝灰岩均不同程度地发生了白云石化作用,白云石晶体以细晶和粉晶为主,呈团块状、星点状,顺层或顺微裂隙分布于凝灰质或泥质基质组分中。孔隙类型主要为粒间孔、晶间孔、溶孔和裂缝,其中溶孔和裂缝为主要储集空间。沉积作用、白云石化作用和构造作用共同影响白云质岩类储层物性。沉积环境决定白云质岩类岩石的分布范围;白云石化作用增强岩石脆性;构造活动下发育大量裂缝,其作为储集空间及渗滤通道,使得溶孔在裂缝周边发育。

Based on the investigation of cores,rock slices and scanning electronic microscope,this paper investigated the reservoir properties and controlling factors of the Permian Fengcheng Formation in Wufeng area,northwestern margin of Juggar Basin.The result shows that siltstone,mudstone and tuff developed in the study area were dolomitized in various extents.Dolomite crystal developed mainly fine crystal and powder crystal.The distribution patterns of dolomite crystal in tuffaceous or mud matrix show three different types：lump,satellite and along bedding or fracture.Intergranular pores,intercrystalline pores,dissolved pores and fractures developed mainly in Fengcheng Formation.Both of dissolved pores and fractures are the main reservoir space.Deposition,dolomitization and tectonism affect the reservoir properties together.Depositional setting determines the distribution of dolomitic rocks,dolomitization enhances rock brittle,and large amounts of fractures developed under tectonism as reservoir spaces and percolation channel,which makes dissolved pores developed around.