## 3 Results and Discussion
### Intensification of Single-Phase Filtration
#### 3.2.1 Medium-Permeability Sandstone  
In the experiment, a liquid of one phase (oil) is filtered through a sandstone plug of medium permeability. The oil contains paraffins and asphaltenes, which block the pore channels of the sample. During the experiment, a number of activations and deactivations of the nonlinear load were performed. In this case, depending on the moment of time when activation is performed, the effect of nonlinear loads is different. Figure 10 shows graphs of changes in experimental data. Figure 10 shows that the permeability changes in proportion to the pressure drop. In turn, the pressure drop is caused by the difference between the pressure at the inlet of the sample and the pressure at the outlet of the sample, as shown in the bottom panel of Figure 10. Looking at the moments of activation of the emitter, for example, at the 31 st minute (second activation), one can see that permeability increases sharply by 25%. This jump is due to the fact that the pressure at the inlet of the sample and the pressure at the outlet of the sample do not change in the same way. At the moment of activation of the nonlinear load, the pressure at the inlet of the sample decreases more significantly than at the outlet of the sample (Figure 11). By lowering the pressure more significantly at the inlet than at the outlet, the pressure drop is reduced. Reducing the fluid pressure at the sample inlet seems logical. It can be assumed that the nonlinear load contributes to the unblocking of the pore space from accumulations of paraffins and asphaltenes in the narrowing of the pore channels (pore throats), i.e., more space is opened up for fluid filtration at the same flow rate, resulting in fluid filtration not requiring the initial high inlet pressure to be maintained. Figure 10: Graphs of experimental parameters during crude oil filtration (medium permeability sandstone). Figure 12 shows a plot of the change in permeability throughout the experiment. Analysis of the graph provides three observations that can be distinguished, as described below. _Observation 1: When oil containing paraffins and asphaltenes is filtered, the permeability deteriorates._  
From the start of the experiment to the end of the experiment, the permeability decreased six times from 60 mD to 10 mD. It is interesting to note that elastic fluctuations affect the permeability decrease trend only at the beginning, where the permeability de  
Figure 11: Graphs of experimental parameters at the 31 st minute. Figure 12: Graphs of change in sample permeability during crude oil filtration (medium-permeability sandstone). The red arrows show the general trend towards a decrease in the permeability of the sample as a result of blocking the pore space. The periods of activation of the nonlinear action are highlighted in blue. creases in accordance with the exponential law. In the future, the graph will become linear with each activation and deactivation of elastic vibrations (this is most noticeable after 1-5 deactivations). The decrease in permeability is most likely due to the deposition of paraffins and asphaltenes in the pore space throats, as a result of which it is more difficult for oil to enter the pore channel, which eventually becomes completely blocked and fluid filtration in it stops. Further, it will be shown that with longer filtration, the pore space of the sample becomes completely blocked. _Observation 2: The activation of a nonlinear load during the filtration of oil containing paraffins and asphaltenes contributes to the restoration of permeability._  
From the point of view of the nature of the change in permeability upon activation of a nonlinear load, three observed effects can be distinguished. The first effect is the restoration of the permeability to some value close to the initial value and its maintenance at a constant level. The first three activations correspond to this effect.