Evolution of Micro-CT
segmented results of the foam pores at different time points for the Belgian strong ale. In situ two-phase flow in porous
media. Two-phase flow in porous media has been studied extensively in several areas such as oil and gas, environmen- tal sciences, and alternative energy [15]. Although lab-based micro-CT has been performed to study this interaction [16], the information gathered has almost always been with the sample in an equi- librium state. Typically, the sample is imaged with one phase, a second phase is introduced and allowed to come to steady state, and then the sample is imaged again with both phases present. Tis provides a nice snapshot of the before and aſter but provides little information concerning the ongoing state as the second phase is introduced. With the advent of lab-based dynamic micro-CT acquisition, research- ers are now able to explore these interim states. As an example, a sintered glass sample was saturated with a brine solu- tion (containing 2 wt % CsCl as the con- trast agent) followed by introduction of an oil phase (n-decane). Both the sample and filter were placed in a Viton sleeve, and a confining pressure was applied around the sleeve. To achieve full water saturation, the sample was first flushed with CO2
at 2 bars for 5 minutes from
the top, followed by water pumped from the bottom (20 μL/min for 1 hour) until it was through the sample. Next, brine was continuously pumped through the sam- ple until the CO2
was removed from the
pore space. Finally, the oil was introduced from the top by changing the direction of the pump (bottom of flow cell). Te primary goal for this test was to
better understand the drainage behav- ior in geological porous materials when undergoing uninterrupted oil injection. Tomographic data were continuously collected in the TESCAN DynaTOM, a unique gantry-based instrument that allows for complex in situ setups, which are not suitable with traditional micro- CT architectures where the sample is required to rotate. A total of 80 scans were collected over a period of 10 min- utes, with each rotation of the sample taking 7.5 seconds at 12.5 μm voxel size. Figure 6 shows a picture of the sample setup in the system, while Figure 7 shows several 3D ren- derings at different time points. Te red areas indicate location of oil infiltration through the porous network. Aſter a time, the
2021 May •
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Figure 6: Flow cell mounted in DynaTOM. The unique horizontally rotating gantry of the system allows for complex in situ dynamic CT such as complex flow experiments.
Figure 7: 3D rendered images showing the full sample at four different time points during a dynamic experi- ment, without interrupting the injection of oil (red) (0, 2.5, 5, and 7.5 minutes).
flow was paused and the micro-CT system was reconfigured for higher resolution, in this case 4.5 μm voxel size, with each rotation taking 60 seconds. Figure 8 provides some detail of the
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