## 3 Results
### Comparison between Laboratory Measurements and Tomographic Images Calculations  
In this section, the samples only with data obtained from both laboratory measurements and X-ray microtomography are compared. Whatever the method used, Normandie, Euville and Lexos present the same trend. Generally, Normandie always has the highest porosity, lowest electrical parameters and smallest pore diameters, while Euville is the opposite and Lexos is comprised between them. Nevertheless, parameters are different depending on the method used. Generally, for similar parameters, results from tomographic images calculations have less variability than petrophysical results. This can indicate that the micropores control some of the large scale properties and heterogeneities, but not the macroscopic parameters. Electrical factors are different between laboratory measurements and XRMT calculations with a focus on tortuosity. Electrical tortuosity \(\tau_{e}\) is obtained from laboratory, while hydraulic tortuosity \(\tau_{h}\) is from XRMT calculations. The two tortuosities are sometimes considered to be similar [19], while \(\tau_{e}\) should sometimes be smaller than \(\tau_{h}\)[44]. In our data set, \(\tau_{e}\) is higher than \(\tau_{h}\). The first hypothesis to explain this difference is that XRMT calculations do not take the microphase in consideration. However, the fluid mainly flows through the connected macropores, and high values of \(PV\) in Table 2 show that there is a good connectivity in the macrophase. The second hypothesis is that the calculation for \(\tau_{e}\) (using Equation (6)) is wrong. Clemnell equation is a simplification of the real expression \(\tau_{e}=\sqrt{F.\phi.f}\) where \(f\) is the constrictivity factor, depending on the pore radius fluctuation ratio. \(f\) is comprised between 0 (e.g., trapped pores) and 1 (e.g., cylindrical pores with constant radius), and is taken to be equal to 1 for convenient in Equation (6) and in many other papers. An estimation of \(f\) for our samples is made with the hypothesis that \(\tau_{e}=\tau_{h}\)[21]. Results are displayed in Table 3. As expected, \(f\) values are mainly not equals to 1. When samples have \(f\) closed to 0, it means that macropores are poorly connected or that the connection is possible by micropores non-visible in tomography. At the contrary, when \(f\) is closed to 1, macropores are well connected and the macrophase is mainly responsible for the fluid flow. Concerning Normandie, once again three groups are shown. N02/N04 have \(f\) closed to 0, N03/N05 have \(f\) closed to 1, and N08/N09 have \(f\)\(\sim\)0.4. Euville samples are homogeneous and have \(f\)\(\sim\)0.4. This means that pore diameters are subjected to vary a lot inside the sample, inducing a difficult fluid flow. This variation in pore diameters were seen in centrifuge (Figure 4). Lexos samples  
Figure 8: Chords length distribution for Lexos samples, pore diameters are displayed by proportion. On the left, an average of chord lengths in the three directions is shown. On the middle and right, chord lengths are detailed in directions X, Y and Z: L01, L04 and L08 on the middle, and L03 and L07 on the right. present high variability, making an interpretation difficult. Nevertheless, we can conclude that constrictivity plays an important role in the rock characterization and should be taken into account. The others global variabilities observed between Tables 1 and 2 are due to the difference between the two poral phase studied. Indeed, XRMT calculations were made based on pores larger than 12 \(\upmu\)m, while laboratory measurements were conducted on the global poral phase. For Normandie and Lexos samples, pores larger than 12 \(\upmu\)m contribute to only 20 to 40% of the poral phase and constitutes around 50% for the Euville samples.