Page 85 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

CHAPTER 4 Hybrid Chemical EOR Using Low-Salinity and Smart Waterflood 77

100
CF-2 Inj. W. 2nd Cycle
CF-1 Inj. W. 1st Cycle
CF-2 S.W. 1st Cycle
In-Situ Viscosity, mPa.s 10
CF-1 S.W. 2nd Cycle

1
1 10 100
Interstitial velocity, ft/d
FIG. 4.10 In situ viscosity of polymeric solutions using high-salinity injecting water and low-salinity water at
various shear rates. (Credit: From AlSofi, A. M., Wang, J., & Kaidar, Z. F. (2018b). SmartWater synergy with
chemical EOR: Effects on polymer injectivity, retention and acceleration. Journal of Petroleum Science and
Engineering, 166, 274e282. https://doi.org/10.1016/j.petrol.2018.02.036.)

result is explained that the low-salinity polymeric solu- acceleration of the polymer front. The coreflooding tests
tion exhibits the significant shear-thinning behavior of conventional polymer flood have the inaccessible
before the shear-thickening behavior. The second exper- pore volumes of 0.136 and 0.142. LSPF shows the
iment estimates the polymer retention at dynamic con- higher inaccessible pore volume with 0.147 and
dition using the polymer mass balance equation of Eq. 0.149. The slight increase in the inaccessible pore vol-
(4.11). ume is attributed to the expansion of polymer molecule
in low salinity condition. The increment in the inacces-
P
V inj C inj; poly V prod C prod; poly
n sible pore volume might improve or, at least, not hinder
G dynamic; poly ¼ (4.11)
W rock the propagation of polymer front. Because the incre-
ment is under the range of experimental uncertainty,
where G dynamic, poly is the polymer retention at dynamic the experimental results might not guarantee the favor-
condition; V inj is the injected volume of polymeric solu- able effect of inaccessible pore volume on the flow of
tion; C inj, poly is the polymer concentration to be polymer in porous media. It is concluded that the suc-
injected; V prod is the produced volume of polymeric so- cessful LSPF should be carefully deployed considering
lution; C prod, poly is the polymer concentration to be the issues of injectivity, dynamic retention, and inacces-
produced; and W rock is the weight of the rock. sible pore volume and then synergy of LSPF might pro-
In the two sets of coreflooding, the conventional duce successful oil recovery.
polymer flood results in the polymer dynamic retention For the heavy oil sandstone reservoir, Almansour,
of 0.230 and 0.133 mg/g of rock. The LSPF yields the AlQuraishi, AlHussinan, and AlYami (2017) also car-
retention of 0.084 and 0.102 mg/g. The usage of ried out the lab-scaled experiments to investigate the
low-salinity water reduces the 1028% of reduction in potential of LSPF process. The study measured the IFT,
the dynamic condition and will save the costs miti- contact angle, and z-potential to quantify the wetta-
gating polymer loss in the bulk of polymeric solution. bility modification effect, but it tested the brines, not
In addition, the experiments also estimate the inacces- polymeric solution. The heavy oil recovery of displace-
sible pore volume by polymer molecules, which differ- ment experiment and rheology of polymeric solution
entiates the depletion in the effluent profile of polymer are also investigated. The Saudi heavy crude oil is sub-
from that of tracer. The inaccessible pore volume, in ject to the experiments and has viscosity of 33 cp and
3
which polymer hardly enters, might promote the faster density of 0.91 g/cm at 60 C and 2000 psi. The syn-

flow of polymeric solution and contribute the thetic formation water of 197,451 ppm TDS is