注水前后储层微观孔隙结构的分形表征

针对用分形分维方法研究储层的微观孔隙结构。提出获得微观孔隙结构分维的两种切实可行的途径，一是利用压汞曲线的分形特性，通过建立油藏条件下压汞曲线的分形模型。计算压汞曲线的分维值来获得；二是利用常规测井解释的孔隙度和渗透率，来预测微观孔隙结构分维。然后对注水开发中后期河流相储层的微观孔隙结构的分维进行了注水前后的计算和对比分析，并对微观孔隙结构参数用分维进行了定量表征，研究了水驱对微观孔隙结构变化的影响。研究表明，储层微观孔隙结构的复杂度在注水后较注水前增加，储层微观非均质性增强，且微观旋回性得到增强；并指出可据此开展流动单元的分类表征研究；储层岩石的束缚水饱和度随着微观孔隙结构分维的增加而增大，水驱时前缘推进越趋不均匀，无水期采收率越趋减小。

Fractal Characterization of Microscopic Pore Structures of Reservoirs Both before and after Water Injection

In consideration of studying microscopic pore structures of reservoirs by using the method of fractal dimension, 2 feasible ways for obtaining fractal dimension for the microscopic pore structures are put forward, of which one is to obtain the fractal dimension by using the fractal characteristics of a mercury curve and calculating the fractal dimension value of the mercury curve by establishing the fractal model of the mercury curve under the reservoir conditions, the other is to predict the fractal dimension of the microscopic pore structures by using the permeability and porosity obtained from conventional well logging interpretation. And then the fractal dimensions of the microscopic pore structure is calculated and contrasted for the fluvial depositional reservoir at the middle and late stages of waterflooding, the parameters of the microscopic pore structure are quantitatively characterized by fractal dimension; the influence of water drive on the microscopic pore structures is studied. It shows that the complexity level of microscopic pore structures increase higher after water drive. The reservoir microscopic heterogeneity and its microscopic cyclicity are enhanced. And it is pointed out that the classified characterization is studied on the flow unit based on the above, the irreducible water saturation of the reservoir rocks raises with the increase of fractal dimension of the microscopic pore structures, the frontal drive tends uneven in water drive, the recovery tends to decrease at the water free stage.