Study on micro-structure of pore in carbonate reservoir in western Hubei and eastern Chongqing area by P-A fractal model

As one comparatively fresh theory in complexity sciences, fractal and multifractal have penetrated into almost all the fields of geosciences, including the distribution patterns of element concentrations, of ore-deposits and of pores in different kinds of rocks. A lot of attention has been paid to the study of micro-structures of Carbonate reservoir rocks in recent years as it has been recognized extensively that traditional parameters, such as porosity and permeability, are not enough to depict the complexity among them. In this paper, 18 samples from outcrops in different strata and 4 samples from cores drilled in Dasan stratum have been selected to study the micro-structures of Carbonate reservoirs and then assess their reservoir properties. By analyzing the binary ESEM digital images of thin sections from the samples, the area and perimeter of each pore in the coated thin section has been calculated and then plotted on the log-log diagram. This P-A fractal analysis of the micro-pore's distribution patterns has shown that the micropores in the samples are of fractal properties and that the average of fractal dimension in samples from Dasan stratum reaches maximum and that from the Changer stratum and Maokou stratum are smaller. By comparing with the experimental physical parameters, it could be concluded that the Dasan stratum is the optimum reservoir, whereas the Changer stratum and Maokou stratum are poorer.