Page 369 - Fundamentals of Gas Shale Reservoirs
P. 369
FACTORS INFLUENCING WATER IMBIBITION IN SHALES 349
Exposure FS in DI-water M in DI-water OP in DI water
time
0 h
72 h
Exposure FS in M in OP in
time 10 wt.% NaCl 10 wt.% NaCl 10 wt.% NaCl
0 h
72 h
Exposure FS in M in OP in
time 20 wt.% NaCl 20 wt.% NaCl 20 wt.% NaCl
0 h
72 h
FIGURE 16.8 Pictures of FS, M, and OP shale samples used in the spontaneous imbibition experiments using 20 wt.% NaCl brine, 10 wt.%
NaCl brine, and DI water (Xu and Dehghanpour, 2014).
16.4.6 Connectivity of Hydrophobic and Hydrophilic materials. Significant water uptake of gas shales may indi-
Pore Networks
cate that the hydrophilic pore network is relatively well
It is well known that the shale pores can either be in connected. Furthermore, this network may be coated by
organic or inorganic materials (Sondergeld et al., 2010). water film and salt which increase its affinity to water,
The organic part of the rock is hydrophobic (Mitchell et al., as discussed earlier. On the other hand, insignificant
1990), while the inorganic part can be hydrophilic, espe- oil uptake of gas shales may indicate that the hydrophobic
cially in the presence of clay minerals. Therefore, organic pore space, partly coated by organic carbon, is poorly
shales are usually a mixture of hydrophilic and hydrophobic connected.
