Pore-Fracture System Distribution Heterogeneity by Using the T[sub.2] Spectral Curve under a Centrifugal State

In this paper, 12 sandstone samples are collected from the Taiyuan Formation in Qinshui Basin, and sample types using the T [sub.2] spectral under LF-NMR saturation and centrifugation conditions are classified. Moreover, single and multifractal models were used to calculate fractal parameters of saturated and centrifugal T [sub.2] spectra, and the correlation between different fractal parameters, pore structure, T [sub.2cutoff] value, and pore permeability parameters was studied. The results are as follows. (1) According to the T [sub.2] spectrum curves under centrifugation and saturation conditions, all the samples can be divided into three types. There are significant differences in the uniform pore size distribution. However, the non-uniformity of small pore distribution in type B samples is stronger than that of other types, while heterogeneity of large pore distribution is weaker than that of different types. The centrifugal T [sub.2] spectrum curve exhibits both single-fold and multifractal characteristics. The results of a single fractal by using a centrifugal T [sub.2] spectrum are consistent with those of a saturated T [sub.2] spectrum, indicating that single fractal features by using centrifugal and saturated T [sub.2] spectra are consistent. Unlike the single fractal parameters, the correlation between the saturation and centrifugal T [sub.2] spectrum’s multifractal parameters is weak. This suggests that the physical significance conveyed by the centrifugal T [sub.2] spectrum’s multifractal parameters differs from that of the saturated T [sub.2] spectrum.