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以四川盆地和塔里木盆地孔隙型白云岩样品为例,通过CT扫描、数字岩心、分形与多重分形等方法,讨论了典型白云岩储层不同孔隙系统(如晶间孔、粒间孔、铸模孔等)的结构特征,并用定量化参数对孔隙结构进行数值表征。结果表明:晶间孔和粒间孔样品的孔隙形状多为三角形,孔隙相对细长,喉道发育,连通性较好;铸模孔样品的孔隙形状较为规整,二维平面上表现为圆形,三维空间上近似球体,这类样品往往孔隙较为发育,但是孔喉系统连通性差;由多种类型孔隙组成的“混合孔”样品则非均质性较强,受岩石组构特征影响显著。进一步利用分形与多重分形方法对孔隙的非均质性进行研究发现:不同孔隙类型的结构差异在分形盒子维数上有明确响应,维数的均值相对大小表现为:铸模孔>粒间孔>晶间孔>混合孔。孔隙度可能也对盒子维数产生影响。
Taking the porous dolomite samples in Sichuan Basin and Tarim Basin as examples, the different pore systems of typical dolomite reservoirs (such as intergranular pores, intergranular pores, and mold pores are discussed by means of CT scanning, digital core, fractal and multifractal methods. Etc.), and quantitatively characterize the pore structure with quantitative parameters. The results show that the shape of intergranular pores and intergranular pores is triangular, the pores are relatively slender, the throat is well developed and the connectivity is good. The shape of the pores in the intercalated intergranular and intergranular pores is regular, These three kinds of samples are similar to spheroids, which usually have more pores but poor connectivity of pore-throat system. The “mixed pores” samples composed of many types of pores are highly heterogeneous and affected significantly by the rock texture . The fractal and multifractal methods are further used to study the heterogeneity of pores. The results show that the structural differences of different pore types have a clear response to the fractal box dimension. The average relative dimension of the dimensions is as follows: mold hole> intergranular hole> Intercrystalline pores> Mixed pores. Porosity may also have an effect on the box dimension.