Page 31 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Huff-n-puff gas injection in oil reservoirs 21

Figure 2.12 Oil recovery factor and matrix average pressure vs. operation time, (A) in a
typical huff-n-puff injection time, (B) zoomed in a typical cycle.

increased, the oil recovery factor became higher (Gamadi et al., 2013). Such
results were confirmed by other researchers in laboratory and simulation,
e.g., Yu et al. (2016a) and Li et al. (2018). Liu et al. (2005) mentioned
that if the gas injection pressure is lower, the gas penetration velocity
become lower; then the injected gas (CO 2 ) may stay near the injector,
reducing gas contact with oil. When the velocity is higher, gas may bypass