Page 279 - Enhanced Oil Recovery in Shale and Tight Reservoirs

256 Enhanced Oil Recovery in Shale and Tight Reservoirs

twin plug initially saturated with water, measure the imbibed oil volume
(saturation). The wettability indices are defined as follows.
S w1
WI w ¼ (9.42)
S w1 þ S o2

S o2
WI o ¼ (9.43)
S w1 þ S o2
The plugs must be set horizontally, especially when the interfacial ten-
sion is low because gravity is relatively more important.

9.8.4 Pore-space imaging methods
Recent advances in microtomography have allowed the noninvasive imag-
ing of fluid distributions in rocks at reservoir conditions. Andrew et al.
(2014) characterized the effective contact angle directly in a carbonate-
brine-scCO 2 system at reservoir conditions using the microtomography
(micro-CT imaging) technology, as shown in Fig. 9.31. The micro-CT

Figure 9.31 Contact angles measured directly in a rock sample (Andrew et al., 2014).