Page 91 - Enhanced Oil Recovery in Shale and Tight Reservoirs

78 Enhanced Oil Recovery in Shale and Tight Reservoirs

Figure 3.17 Reductions by asphaltene deposition in oil recovery factor at different huff
pressures.

6000, and 5000 psi. It shows that as the huff pressure is increased, the reduc-
tion in oil recovery is higher. It implies that a lower huff pressure should be
used to decrease the effect of asphaltene deposition. However, Fig. 3.18
shows that the oil recovery factor at a higher huff pressure is still higher
than that at a lower huff pressure, even asphaltene deposition is included
in the simulation. It means that the negative effect of asphaltene deposition
on oil recovery is less than the positive effect of higher pressure. Then a
higher huff pressure should be chosen to improve oil recovery. This conclu-
sion is drawn when asphaltene is not taken into account (Gamadi et al.,
2013; Yu et al., 2016a; Li et al., 2018).
Similarly, Fig. 3.19 shows that as the puff pressure is decreased, the
reduction in oil recovery by asphaltene deposition is higher. However,
Fig. 3.20 shows that the oil recovery factor at a lower puff pressure is still
higher than that at a higher puff pressure, when asphaltene deposition is
included in the simulation. The negative effect of asphaltene deposition
on oil recovery is less than the positive effect of lower puff pressure. There-
fore, a lower puff pressure should be chosen to improve oil recovery. This
conclusion is drawn when asphaltene is not taken into account (Sheng
and Chen, 2014; Sheng, 2015b; Sanchez-Rivera et al., 2015).