## 3 Results
### Petrophysical Properties from Laboratory Measurements
These differences in electrical properties (\(F_{lab}\), \(m_{lab}\) and \(\tau_{e}\)) are explained by differences in mechanical properties (Table 1) and micropores proportions (Figure 4). First concerning Normandie, N02 and N04 present both very low permeabilities  
Figure 4: Pore diameters distribution from the centrifugation measurements. Results for Normandie samples are on the left, Euville in the center, Lexos on the right. Figure 3: Crossplot of formation factor over porosity depending on the rock type. Diamonds are for Normandie, squares for Euville and circles for Lexos. Lines of equal cementation factors according to [PERSON]’s law (Equation (5)) are also displayed. (around 5 mD) and very high tortuosities (around 3.7) compared to other samples, so they both present a low connectivity. Also, they both have similar low porosities and high electrical factors, but N02 has lower velocities of P and S waves and higher proportion of micropores than N04 (72% against 62%). N02 is therefore considered to be a less cohesive sample than N04 [7; 46]. Then, N08 and N09 present same low porosity, medium electrical properties and micropores proportion (66%), but differ in permeability and \(Vp\). N09 has a lower permeability, which can be related to a higher \(Vp\), inducing a better cohesiveness [46]. Finally, N03, N05, N11 and N13 are part of the group with the highest porosities and lowest electrical factors. However, N03, N05 and N11 have permeabilities around 11 mD while N13 has the double. Moreover, while they all present low \(Vp\), N03 and N05 both have around 80% of micropores while N13 only counts 70%. Therefore, with a higher proportion of large pores, N13 has a less complex poral system than the three others, inducing a better permeability [27]. Despite great similarities, some particularities were found in the Euville samples set. Two groups of samples can emerge from Figure 3 and Table 1 in terms of structural properties: E05/E06/E08 with high electrical factors while the other samples have low electrical factors. However, when looking at \(Vp\), two other groups emerge: E01/E05/E07/E08 with high \(Vp\) (around 3.8 km/s) while E02/E03/E04/E06 with low \(Vp\) (ranging from 2.3 to 2.7 km/s). Two groups overlap: E05/E08 with high structural factors (\(I_{lab}\), \(m_{lab}\) and \(\tau_{e}\)) and \(Vp\), and E02/E03/E04 with low ones. E01, E06 and E07 present values which oscillate between the two groups. However, it should be noticed that samples with low permeabilities have high \(Vp\) and low proportions of small pores, which is consistent with literature [7; 46]. The Lexos samples set seems to present more variability. From Figures 3 and 4, two groups emerge. On one hand, L01, L02, L04, L05, L08, L10 and L11 are samples with high porosities, globally low formation factors. They present more than 60% of pores with sizes comprised between 3.2 and 46 um, which can be considerate as intermediate size pores. On the other hand, L03, L06, L07, L09 and L12 have low porosities and mainly high formation factors. They also count the highest proportion of micropores (pores with diameters smaller than 10 um), and especially a lot of very small pores, with more than 40% of pores smaller than 3.2 um and more than 50% of this proportion is composed of pores smaller than 1.3 um. In these previous two consistent groups, P-wave velocities differ for samples. In the first group, L02, L04 and L05 present low \(Vp\), which is consistent with high porosities [46] and high proportion of micropores, inducing a low cohesiveness [7]. Contrarily, L01, L08 and L11 have high \(Vp\). For L01 and L08, these high values are correlated with a low proportion of micropores (61 and 57% respectively) compared to other samples which induces a better cohesiveness. However, L11 has a relatively high proportion of micropores (67%), but also has a high value of Bulk modulus K, inducing a low compressibility, which is usually correlated with a high cohesiveness.