## 3 Result and Discussion
### Correlation of Rock Core Physical Properties  
The NMR method accurately reflects pore size distribution, whereas MICP measurements may underestimate the proportion of macro-pores and overestimate that of meso-pores. The discrepancies between the two methods are consistent with numerous  
Figure 12: A comparison of pore-throat size distributions in shale as determined by NMR and MICP methods: (**a**) H1-1, (**b**) H1-2, (**c**) H2-3, (**d**) H2-4, (**e**) H3-6, (**f**) H4-7, and (**g**) H4-8. studies conducted by other researchers. We suggest that the differences in information obtained from dynamic and static methods reflect meaningful physical characteristics that can serve as characteristic values for porous media. Taking the sandstone core S1-1 as an example, the study investigates the volume overestimated in the MICP method and the pore throat radius controlling mercury intrusion into the large pores. Figure 13 illustrates the relationship between cumulative frequency distribution and pore size in NMR and MICP experiments. It is observed that at larger pore sizes, particularly when mercury intrusion just begins, the cumulative frequency of NMR is higher than that of MICP. As the mercury intrusion pressure increases and mercury enters pores of 1.2 \(\upmu\)m, the cumulative frequencies of both methods become equal. The pore radius corresponding to this equal cumulative frequency is defined as controlled throat radius r\({}_{\text{c}}\). In MICP, r\({}_{\text{c}}\) represents the pore throat radius restricting mercury entry into larger pores. When the injection pressure increases to a point where mercury can enter large pores controlled by r\({}_{\text{c}}\), the cumulative frequencies of MICP and NMR align. The cumulative frequency distribution corresponding to r\({}_{\text{c}}\) is then twice the volume of pores controlled by r\({}_{\text{c}}\). Defining the volume controlled by pore throat r\({}_{\text{c}}\) as F\({}_{\text{rc}}\), it is evident from Figure 13 that in core S1-1, 4.91% of the pore volume is influenced by r\({}_{\text{c}}\). It is noteworthy that the primary differences between MICP and NMR are observed in the low capillary pressure range. There is a significant size disparity between the throats and pores in this range. However, in the high capillary pressure range, the diameters of the pore throats are similar, and no significant discrepancies between the two methods are observed. Therefore, it is considered that the controlled volume by throat size at r\({}_{\text{c}}\) contributes dominantly to the permeability. In the past, Dr. [PERSON] [64] found that r\({}_{\text{35}}\) (the radius corresponding to the point at which mercury intrusion volume reaches 35% of the total pore volume of the core) controlled fluid volume is dominant in the flow though feature and used r\({}_{\text{35}}\) to quantify the rock quality from a statistical point of view. [PERSON] et al. [65] classified reservoir rock types based on micro-CT results and then evaluated rock quality for different rock types using the Winland method [65]. The empirical expression is as follows:  
\[\text{logr}_{\text{35}}=0.732+0.588\text{logK}_{\text{a}}-0.864\text{log}\Phi \tag{7}\]  
where r\({}_{\text{35}}\) represents the radius corresponding to the point at which mercury intrusion volume reaches 35% of the total pore volume of the core, measured in \(\upmu\)m. K\({}_{\text{a}}\) is the absolute permeability of the core, expressed in mD, and \(\Phi\) is the porosity of the core, denoted in %. Figure 13: The cumulative frequency distribution by NMR and MICP (S1-1). According to Equation (7), the porosity-permeability graph merged with the Winland r\({}_{35}\) method (Figure 14) can be derived. It is observable from the figure that sandstone and shale predominantly occupy two distinct regions. Furthermore, the traditional Winland r\({}_{35}\) method underperforms in characterizing the attributes of our samples.