Page 92 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

84 Hybrid Enhanced Oil Recovery using Smart Waterflooding

carbonate systems having fracture widths of 0.2, 0.5, of 1% NaCl brine still increases the oil production.
and 0.8 cm are subject to the displacement tests. The The postflush results in the increasing injection pressure
displacement experiment is designed with pre- and after PPG injection with 0.01% NaCl brine. However,
postflushes injecting 1% NaCl brine and PPG injection the other PPG injections with 0.1% and 1% NaCl brines
with various brines of 0.01%, 0.1%, and 1% NaCl. The lead to the significant drop in the injection pressure for
oil recovery and injection pressure are measured the postflush injection. The PPG injection with higher
(Fig. 4.16), and the residual resistance factor is calcu- salinity shows the more decreases in the injection pres-
lated from the injection pressure measured. sure as well as oil recovery for the postflush of 1% NaCl
In the fracture system of fracture width with 0.2 cm, brine. It is clearly confirmed that low salinity condition
PPG injection with 0.01% NaCl brine recovers higher of the gel solvent is favorable to the gel swelling and re-
oil than PPG injections with 0.1% and 1% NaCl brines. sidual resistance factor increasing oil recovery and injec-
This higher incremental oil production is attributed to tion pressure. In addition, the swollen gel by low
the higher swelling ratio in lower salinity condition. Af- salinity condition is still effective to recover oil and in-
ter the PPG injection with 0.01% NaCl brine, postflush creases the residual resistance factor during the high-

FIG. 4.16 History of (A) oil recovery and (B) injection pressure of the experimental results of hybrid low
salinityeaugmented gel treatment. (Credit: From Alhuraishawy, A. K., & Bai, B. (2017). Evaluation of combined
low-salinity water and microgel treatments to improve oil recovery using partial fractured carbonate models.
Journal of Petroleum Science and Engineering, 158,80e91. https://doi.org/10.1016/j.petrol.2017.07.016.)