饶阳凹陷油藏储量在空间分布的分形特征

Fractal Characters of Oil Reserves in Spatial Distribution in Raoyang Sag

在油藏级别划分的基础上,研究了饶阳凹陷201个油藏储量规模的分形曲线,认为该区今后勘探工作中发现112×104t级别以上的油藏难度较大,28×104～112×104t的油藏有一定的勘探潜力,大量28×104t以下的油藏待探明;计算前古近系、沙河街组、东营组、新近系4个层位油藏储量规模的分形维数,并统计各层系油藏的分形特征值,认为沙河街组勘探潜力最大,其次为东营组,新近系发现油藏的概率大于前古近系,但发现30×104t以上油藏的机会不如后者;通过对比整体、前古近系、沙河街组油藏空间分布的分形特征,发现整体分形维数远大于分层分形维数。分形维数的大小反映含油面积,而不能直接代表储量的大小。

Based on the classification of reservoir grade, the reserves fractal curves of 201 reservoirs in Raoyang sag are studied. The results indicate that in future exploration it is difficult to find reservoirs with more than 112×10^4 t reserves; the reservoirs with （28-112）×10^4 t reserves are of certain exploration potentials, and most reservoirs with less than 28×10^4 t reserves are to be proven. By calculating the fraetal dimensions of reserves of pre-Paleogene, Shahejie formation, Dongying formation and Neogene reservoirs and counting fractal eigenvalues of reservoirs of every sequence, it is suggested that Shahejie formation is of the greatest exploration potential, followed by Dongying formation, Neogene and pre-Paleogene. However, there are more opportunities to find reservoirs with more than 30×10^4 t reserves in pre-Paleogene than that in Neogene. By comparison among fractal characters of spatial distribution of all reservoirs, prePaleogene reservoirs and Shahejie reservoirs, it is found that the whole fractal dimension （D） is much greater than layered fractal dimension, so the size of D only reflects the oil-bearing area, but it can not represent the size of reserves directly.