Bentheimer sandstone samples

Our method is demonstrated with experiments on a Bentheimer sandstone sample. The sample was prepared to be cylindrically shaped with a diameter of 2.5 cm and a length of 2.0 cm. The sample was fully saturated with de-ionized water under vacuum. We performed the CPMG imaging experiment described in the previous section to measure the magnetization intensity at 50 echoes spaced by 4.6 ms for each of 32 x 16 x 16 voxels within the field of view of 3.0 cm x 3.0 cm x 3.0 cm. The corresponding voxel size is 0.938 mm x 1.88 mm x 1.88 mm. We used 1 s of repetition time (TR) and the total imaging time was 4.3 min. 

We demonstrate the procedure with an experiment conducted on a Bentheimer sandstone sample. For simplicity, we use a relatively thin sample and resolve only the two in-plane spatial coordinates. The sample is a rectangular parallelepiped shape having a length of 50 mm extending in the z direction, width 25 mm along the z2 direction and thickness 5 mm in the z3 direction. The sample was sealed laterally with epoxy and mounted in Plexiglass end-plates with O-rings and tube... 

Fig. 4.1.7 Superficial average velocity data for the flow experiment with the thin Bentheimer sandstone sample. Each arrow represents the direction and relative magnitude of the superficial average velocity at the corresponding voxel. The velocities are measured for 58 x 20 voxels.

Two different sandstone samples are used to demonstrate the methodology developed in Sections 2.1-2.3 in one spatial dimension. The first sample is a Bentheimer sandstone sample we have labeled KBE, which is saturated with oil. The second sample is a Brown sandstone sample, labeled MCD, that is saturated with water. 

Fig. 2. One-dimensional CPMG images and the intrinsic magnetization for a Bentheimer sandstone sample (KBE).

Fig. 3. Predicted and observed magnetization of the Bentheimer sandstone sample (voxel 80).

The developed methodology is now used to determine a two-dimensional porosity distribution on a Bentheimer sandstone sample (KBE) saturated with oil. The sample and reference used are the same as those for one-dimensional imaging in Section 2.4.1. A two-dimensional CPMG imaging sequence is applied with field of view of 10.00 cm x 3.50cm, which gives a voxel size of 0.078 cm x 0.11 cm x 0.58 cm. The porosity distribution of the two-dimensional... 

The method to determine fluid velocities is described in Section 3.1. The inverse problem is described in Section 3.2, and demonstrated on data from a Bentheimer sandstone sample in Section 3.3. 

Fig. 12. The joint spin-velocity density function, p(z)P (v , -), as a function of position z for water flow in the rectangular Bentheimer sandstone sample (voxel size is 0 94 mm)...

Figure 13 shows an example of (zM with respect to each voxel located at (z, x) for a fluid flowing through a Bentheimer sandstone sample, Fig 14. 

Fig. 15. Two-component velocity distribution with the Bentheimer sandstone sample.

An example of a joint density function gA (r, R) is shown in Fig. 12. The sample is a Bentheimer sandstone in a rectangular parallelepiped shape 50 mm long extending in the -direction, 25 mm wide along the x-direction, and 5 mm thick in the y-direction. The average volumetric flow rate of the water was 1.5 ml min-1 along the -direction. The sample is located between the two spikes resulting from free water present in the end caps of the core holder. 

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