Study on Fractal Structure of Pore Space of Sandstones Based on NMR and Capillary Pressure Curves

We apply the fractal equation of pore distribution and NMR spectrum to 25 sandstone samples from several boreholes in China, and we show the results of the relations between NMR, fractal dimension and capillary pressure. The fractal dimensions can be calculated from NMR and capillary pressure data, and the value of correlation coefficient could indicate whether the pore structure shows fractal features. For the same core sample, there are different fractal dimensions in different pore radii ranges, indicating that core pore space has multiple fractal structure. The fractal dimensions determined from NMR data is lower than the values determined from capillary pressure data, this is due to the different pore throat space reflected by these two methods. The fractal dimension from NMR data can better represent the rock’s physical properties.