Page 239 - Fundamentals of Enhanced Oil and Gas Recovery

Waterflooding 227

1
Figure 7.9 Wettability map in different pH and Na concentration [45,79].
Robertson [81] compared three waterflooding field performances in Wyoming.
The reservoir was pre-flushed using surfactant-polymer; With a lower salinity ratio, a
higher oil recovery was obtained. preflush water should bring incremental oil if LS
waterflooding worked. However, apparently, no oil rate increase was observed during
the fresh water preflush in the North Burbank Unit surfactant polymer pilot in
Osage County, Oklahoma [82] and Loudon surfactant pilot [83]. Thyne and Gamage
[84] evaluated the LS flooding effects in the fields in the Powder River Basin of
Wyoming. They found no increase in recovery for the 26 fields where LS water was
injected when they compared with the 25 fields where mixed water or formation
water was injected [45].
Skrettingland et al. [85] evaluated LS flooding for the Snorre field. A SWCTT
did not show a significant in oil recovery factor; they explained why low salinity
water injection did not have a considerable effect because of the reservoir was in an
optimum wettability condition. As a result, such an EOR method could not work
for this reservoir [45].

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[3] S.E. Buckley, M. Leverett, Mechanism of fluid displacement in sands, Trans. AIME 146 (1942)
107 116.
[4] H.J. Welge, A simplified method for computing oil recovery by gas or water drive, J. Pet. Technol. 4
(1952) 91 98.
[5] Sheldon, J., Cardwell Jr, W., 1959. One-dimensional, incompressible, noncapillary, two-phase fluid
flow in a porous medium.