Page 165 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Gas flooding compared with huff-n-puff gas injection 149

Table 6.3 Gas flooding performance.
m o , # # Well Performance,
Field Inj. gas k, mD cP Inj Prod spacing MSCF/bbl References
Viewfield, Lean 0.01e 2e3 1 9 80, 160 Oil rate Schmidt
Bakken gas 0.1 acres increased, and
formation, 6.5e10 Sekar,
Saskatchewan 2014
Bakken Natural 1 4 Oil rate Hoffman
formation, gas improved and
North Evans,
Dakota 2016
0.79 6.6 14 26 200e 53.75 Jiang et al.,
Song-Fang-Dun, CO 2
Daqing 300 m 2008
Fuyang Daqing CO 2 0.96 3.6 7 17 4.73 Wang 2015

1. Three out of four projects that demonstrated gas injection were success-
ful with more oil produced.
2. The formation permeabilities were less than 1 mD, but much higher than
nanoDarcy.
3. The oil viscosities were low.
4. Tests showed there was no gas injectivity issue. Some cases rather showed
gas breakthrough issue.

6.5 Feasibility of gas flooding
Joslin et al. (2017) used simulation approach to study the feasibility of
flooding methods in a volatile oil reservoir. They found that when the
matrix permeability is lower than 0.03 mD, any flooding method, nitrogen,
CO 2 , and water, will not be economical at the oil price of $40/bbl oil and
the gas price of $2.5/MSCF. Nitrogen flooding is the best option when the
matrix permeability is 0.03e0.1 mD in terms of incremental oil recovery.
CO 2 is the best when the matrix permeability is higher than 0.1 mD. In
terms of net present value (NPV), when the matrix permeability is higher
than 0.1e0.3 mD, nitrogen flooding is profitable, but not for CO 2 flooding.
When the matrix permeability is higher than 0.3 mD, both nitrogen and
CO 2 flooding outperformed primary depletion. Waterflooding requires
the matrix permeability greater than 1 mD to be profitable.