Page 100 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Huff-n-puff injection in shale gas condensate reservoirs 87

Figure 4.8 Condensate recovery during a gas flooding experiment.

For the huff-n-puff experiment, one cycle took 30 min of injection
(puff) and soaking time and 30 min of production (puff) time, totaling
1 h. One cycle lasted 1 h, and total five cycles took 5 h. Thus, the conden-
sate recovery can also be plotted in terms of experimental time (similar to the
operation time in a field project). The condensate recovery from the huff-n-
puff injection and the flooding is compared in Fig. 4.9. For the same period
of 5 h, the condensate recovery was increased by 23.3% by huff-n-puff gas
injection; but it was increased by 18.6% by gas flooding. This comparison
showed outperformance of huff-n-puff gas injection over gas flooding.
For huff-n-puff gas injection, the pressure near the well dropped and is
depleted during the puff period; during the huff period, the pressure can

Figure 4.9 Performance comparison of huff-n-puff with gas flooding.