Page 48 - Enhanced Oil Recovery in Shale and Tight Reservoirs

36 Enhanced Oil Recovery in Shale and Tight Reservoirs

Figure 2.26 Comparison of oil recovery from N2 and C1 when live and dead Wolfcamp
oils are used.

In condensate reservoirs, Sheng et al. (2016) observed from a simulation
study that the liquid condensate recovery from CO 2 injection is little bit
higher than that from the methane injection, but it is much higher than
that from nitrogen injection because it is more difficult for nitrogen to be
miscible with liquid oil. However, Sheng (2015b) observed that the liquid
oil recovery from CO 2 injection is lower than that from C 1 injection
because the total volume of injected CO 2 is 15% lower than that of injected
C 1 for the same injection pressure. Sharma and Sheng (2017, 2018) found
that ethane is the most effective agent to recover liquid condensate
compared with methane and solvents like methanol and isopropyl alcohol
(IPA).
In principle, if the injected agent is more similar in its properties to liquid
oil, the liquid oil recovery will be higher under the same injection condi-
tions and injection volume. Other operation issues need to be considered.
For example, CO 2 injection may have issues like corrosion, hydrate and
lack of availability near a large field operation; it may cause an asphaltene
deposition issue (Shen and Sheng, 2017a; 2017b, 2018).