Page 148 - Enhanced Oil Recovery in Shale and Tight Reservoirs

132 Enhanced Oil Recovery in Shale and Tight Reservoirs

According to the Sheng’s (2015d) simulation results, some years of primary
depletion assists the subsequent production of oil by gas flooding and
huff-n-puff gas injection. Meng and Sheng (2016a) proposed that in the
huff-n-puff gas injection in gas condensate reservoirs, the puff time should
be started when the gas rate at the end of puff period should be 10% of
the gas rate in the beginning. It suggests that the first huff-n-puff cycle
should be started when the primary oil rate is depleted to a low enough
rate, for example, 10% of the initial rate. There is no criterion proposed
in the literature.