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42 Enhanced Oil Recovery in Shale and Tight Reservoirs
Figure 2.34 Effect of diffusion on gas flooding oil recovery at different fracture
spacings.
Figure 2.35 Effect of diffusion on huff-n-puff methane injection.
about 50 ft to 100 ft, the increase in oil recovery with diffusion compared
with the case without diffusion is about 10%. Yu et al.’s (2014b) simulation
shows that the incremental oil recovery factor is 3%e4% using a diffusion
2
coefficient of 10 8 m /s. In their model, one huff-n-puff is 6 months of
huff, 3 months of soaking, and 12 months of puff, and this cycle is repeated
for 30 years.
Li and Sheng (2017a) simulated huff-n-puff CH 4 injection with and
without diffusion. The molecular diffusion coefficients are calculated using
