柴达木盆地北缘断裂构造分形特征与油气分布关系研究

FRACTAL CHARACTERISTICS OF FRACTURAL STRUCTURES AND ITS RELATION TO OIL-GAS DISTRIBUTION IN NORTH QAIDAM BASIN

本文应用分形几何理论对柴达木盆地北缘断裂体系的分布进行了定量研究 ,在研究标定尺度范围内 ,该区断裂体系的平面分布具有良好的统计自相似性和分形特征 ,在双对数坐标系中 ,用最小二乘法进行直线拟合的相关系数平方 (R2 )均在 0 .97以上。该区 4个已知油气田断裂构造的分维数 D值均大于 1 .3,明显高于整个区域内 4个反射层的断层分维数 (平均 D=1 .2 1 8)。可以认为断裂构造的分维值大于 1 .3的部位是该区油气聚集分布的有利区。断裂体系分数维值越大的地区 ,有利于油气藏的分布 ,其单位面积内的油气地质储量越高。

To apply the principle of fractal geometry on study of the two dimensional distribution of fracture systems, the fracture systems have the statistical self similar characters and fractal characteristics in the scale extent studied in the North Qaidam Basin. The square of correlation coefficients( R 2 )by least squares lines fitting are more than 0 97 in log log coordinate system of box counting number and the scale. The D values of fractal dimension of fracture systems in 4 known oil and gas fields are more than 1.3, which is obviously higher than that of the whole district of 4 reflection layer(the average D value is 1.218). The locations that the D values of fractal dimension of fracture system exceed 1.3 are favorable to accumulate oil and gas. The higher the D value,the more favorable the conditions and larger the abundance of oil and gas.