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Using Nanofluids to Control Fines Migration in Porous Systems 187

Figure 4.4 Nanoparticles and fines concentration profiles and cumulative effluent
fines quantities with and without nanoparticles coinjection (Yuan et al., 2016).

4.4.2 Approach II: Precoat porous media with nanofluids
prior to fines invasion

As illustrated in Fig. 4.3B, before the introduction of new fine particles
into porous medium, a nanofluid slug is injected to coat the surfaces of
rock grains and thereby modify the surface potential of the rock grains.
As a result, the attractive forces between mobile fines and rock grains are
enhanced, which could help mitigate the further movement of newly
injected fines later. To characterize the enhanced attachment capacity of
fines onto pore surfaces, the maximum retention concentration of fines
onto rock grains is also applied, which can be also enlarged by the contri-
butions of pre-coated nanoparticles onto rock grains, see Eq. 4.7a-c
(Yuan et al., 2016, 2018b).