岩层厚度对碳酸盐岩构造裂缝面密度和分形分布的影响

摘要

Layer thickness is fairly important for the development of structural fractures in carbonate strata. According to statistical analys is, of the profile measuring results of Dawangou, Qingsong and Penglaiba of Keping, Xinjiang, the surface densities of structural fractures in carbonate strata is negatively correlated to layer thicknesses. The thicker the layer is, the smaller the fracture densityis. But the scale of fractures is relatively bigger; when the layer thickness becoming thinner, the fracture density is linearly increasing, meanwhile, the scale of fractures is getting relatively smaller. Structural fractures in carbonate strata own good fractal characteristics. Statistics shows that there is a negative correlation between fracture fractal dimension and layer thickness. Fracture fractal dimension becomes bigger when layer thickness gets smaller, which indicates a better fracture development. Certain linkage exists between fractal dimension and density of fractures, which can together quantitatively describe development level of fractures. Generally, fracture fractal dimension increases wiih increasing fracture density. If fractures have the same density, the bigger fractal dimension is, the more uniform the distribution of fractures is. Meanwhile, permeability of the carbonate layers is poorer.%岩层厚度对于碳酸盐岩构造裂缝的发育起到重要作用.新疆柯坪大湾沟、青松和蓬莱坝构造性质比较稳定,剖面的构造裂缝测量结果统计分析表明,碳酸盐岩构造裂缝面密度与层厚呈负相关关系,层厚越大,构造裂缝面密度越小,但裂缝规模较大；随着层厚减薄,构造裂缝面密度线性增大,但裂缝规模较小.碳酸盐岩构造裂缝具有良好的分形特征,统计结果显示,构造裂缝分数维与层厚呈负相关关系,层厚越小,构造裂缝分数维越大,裂缝越发育.构造裂缝分数维与裂缝面密度有一定的联系,两者可以共同定量描述构造裂缝发育的程度.通常,分数维随着裂缝面密度增大而增大.在裂缝面密度相同条件下,分数维越大,裂缝分布越均匀,碳酸盐岩地层渗透性越差.