Page 288 - Fundamentals of Enhanced Oil and Gas Recovery

276 Mohammad Ali Ahmadi

a problem in a case of huff-n-puff injection mode. Wan et al. [33] compared the oil
recovery from CO 2 flooding with that from huff-n-puff CO 2 injection and found
that CO 2 huff-n-puff outperformed CO 2 flooding. Sheng and Chen [11] also com-
pared gas flooding with huff-n-puff and their simulation results show that huff-n-puff
oil recovery factors are higher than flooding ones. Yu et al. [34] performed experi-
mental investigation to determine the performance of continuous gas injection com-
pared to huff-n-puff CO 2 injection. They concluded that if the soaking period is
short then the oil recovery factor gained by CO 2 huff-n-puff scenario will be higher
than continuous CO 2 injection. Meng et al. [35] carried out different flooding
experiments to evaluate the liquid condensate recovery in both huff-n-puff and con-
tinues schemes. The experimental results reveal that huff-n-puff is much higher than
that the gas injection with continuous setting.
Shoaib and Hoffman [36] conducted different carbon dioxide injection scenarios
including huff-n-puff, continuous carbon dioxide flooding in Elm Coulee Field in
Richland County, United States. They employed various well configurations in their
numerical simulation design. The reservoir formation of this field is Bakken forma-
tion; this formation is a main production zone in this oil field. Design of carbon diox-
ide injection in a huff-n-puff mode was 3 months for injection, 3 months as a soaking
time, and 3 months for production time. Using such a scheme they gained 2.5%
improvement in oil recovery factor from primary production scenario; in huff-n-puff
scheme they achieved this value by injecting 0.19 pore volume (PV) of the reservoir.
Their simulation results revealed that the continuous carbon dioxide flooding is much
better than the huff-n-puff CO 2 injection scenario. Based on their results the continu-
ous CO 2 injection improved oil recovery factor by 14-15%. Lower performance of
CO 2 huff-n-puff scenario attributed to the parameters of this method which are not
optimum value. Consequently, the performance of such a method lower than the
continuous mode [7]. Also, very high permeability has a good contribution in the
performance of continuous carbon dioxide flooding [11].
Wang et al. [15] carried out numerical reservoir simulation to evaluate the EOR
potential of the Bakken reservoir in Saskatchewan. Their results reveal that continuous
carbon dioxide injection works much better than that CO 2 huff-n-puff scenario in
such a formation. The main reason for this conclusion is in their reservoir simulation
they considered huff-n-puff as a single cycle with 10 years as an injection time, 5 years
as a soaking period, and 5 years as a production period. As discussed in previous sec-
tions, in a cased of huff-n-puff injection mode there are lots of parameters that should
be optimized. In their study, these parameters obviously not optimized and too large.
Kurtoglu [37] performed numerical simulation for carbon dioxide huff-n-puff sce-
nario with three horizontal well configuration. In his model,all the wells are parallel
and the central well was employed as an injection well; the two side wells were used
as production wells. He also compared the results with the case of continuous CO 2