Page 217 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

Using Nanofluids to Control Fines Migration in Porous Systems 191

production using nanoparticles until the moment when the fines-effluent
concentration increases to become the injected condition. By comparing
the calculated MI of the two different approaches described, Yuan et al.
(2018a,b,c) established that approach II (i.e., the pretreatment of the reser-
voirs or fracture packs with nanoparticles) performs better than approach I
(i.e., to coinject nanofluids into fluid stream as additives) to fixate the
injected fines and prevent fines moving further. This performance differ-
ence can be explained by the decrease of interaction efficiency between
nanoparticles and fines, although both of them are mobile along with
nanoparticles-fines reactions.

8
Ð t D3
C FP;ini φð1 2 S or ÞAL 3 t D1 1 C FP;eff φð1 2 S or ÞALdt
>
1 2
> t D2
> Scenario I
>
C FP;inil φð1 2 S or ÞAL 3 t D1 1 C FP;inj φð1 2 S or ÞAL 3 ðt D3 2 t D1 Þ
>
<
MI 5
Ð
t cr ðx D 51Þ
> C FP;eff φð1 2 S or ÞALdt
> 1
> Scenario II
>
>
C FP;inj φð1 2 S or ÞAL 3 ðt cr ðx D 5 1Þ 2 1Þ
:
(4.9)
For the case involving constant injection rates and constant injected
nanoparticles concentrations, the pressure differentials along the 1-D per-
meable medium increase with the accumulation of fines attachment and
straining. The severe permeability impairment can be indicated by the
increase of injection pressure drop using Eq. (4.1) (Yuan et al., 2017b).
Yuan et al. (2017a,b) developed analytical solutions to explain the increase

Figure 4.7 Permeability changes obtained from analytical models (solid line) and
laboratory experimental results (discrete points) for both cases (case with nanoparti-
cles effects; and reference case without nanoparticles (after Yuan et al., 2017b)).