准噶尔盆地乌—夏地区二叠系风城组致密油储层特征

近年来,致密油已成为国内外油气勘探的新热点.通过岩心、普通薄片、铸体薄片、扫描电镜、阴极发光薄片的观察和鉴定以及物性压汞数据分析,对准噶尔盆地乌—夏地区二叠系风城组致密油储层岩石类型、储集空间特征、物性特征及储层“甜点”区主要影响因素进行了系统研究.结果表明：风城组主要发育5种岩石类型：云质岩类、凝灰岩类、砂岩类、泥岩类和盐岩类,并以云质岩类为主;致密油储层常见4类储集空间类型：裂缝、溶孔、晶间孔和原生粒间孔,其中裂缝占储集空间的53％,溶孔占储集空间的35％;油层属典型低孔、低渗致密储层,孔隙度为1％～10％,平均为3.86％,渗透率＜2 mD的样品占85％以上,平均为0.17 mD;致密油储层“甜点”区主要受白云石化、裂缝和溶孔发育程度等的共同影响.

Characteristics of tight oil reservoirs of the Permian Fengcheng Formation in Wu-Xia area,Junggar Basin

Tight oil reservoirs have become popular targets in petroleum exploration both at home and abroad in recent years. This paper studied the rock types, reservoir space, physical properties and main influencing factors for ＂sweet spots＂ of tight oil reservoirs of Permian Fengcheng Formation in Wu-Xia area by using petrography, SEM, cathodoluminescence and core analysis. The result shows that the reservoir of Fengcheng Formation consists of dolomitic rock, tuff, sihstone, mudstone and salt beds, with the first present predominantly in the reservoirs. The main reservoir spaces are fractures, dissolved pores, intracrystalline pores and intergranular pores. Fracture and dissolved porosity in the reservoirs are around 53% and 35% respectively. The porosity is 1%~ 10%, with an average porosity of 3.86%. The average permeability is 0.17 mD, and the samples that the permeability is less than 2 mD account for more than 85%. The reservoir belongs to low porosity and low permeability reservoir. The ＂sweet spots＂ of the tight oil reservoir is mainly influenced by dolomitization, fracturing and dissolution.