Page 64 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

48 Gas Wettability of Reservoir Rock Surfaces with Porous Media

50
45
40
1000 mg/L
35
500 mg/L
30 300 mg/L
H 2 /(cm) 2 25
20
15
10
5
0
0 5 10 15 20 25 30 35 40 45 50
3
t /×10 s
FIGURE 2.13
Relationship of self-absorption height and time of water in quartz sand treated with FC911.

60
100 mg/L
55
80 mg/L
50 50 mg/L
45 30 mg/L
40 20 mg/L
35
10 mg/L
H 2 /(cm) 2 30 0 mg/L
25
20
15
10
5
0
–5
0 100 200 300 400 500 600 700 800
t/s
FIGURE 2.14
Relationship of self-absorption height and time of n-decane in quartz sand treated with FC911.

water phase and oil phase is measured. The self-absorption height square H 2
of water and oil has a linear relationship with time t (Figs. 2.13 and 2.14).
Linear fitting is conducted for data in Figs. 2.13 and 2.14, and contact angles
of quartz sand treated with FC911 of various concentrations with respect to
water phase and oil phase is based on the Eq. (2.14). The result is displayed
in Table 2.5.
From Table 2.5, it can be seen that when quartz sand is treated with FC911 in
low concentration (10 100 mg/L), the surface of quartz sand is oil-wet. As
concentration increases, wettability changes from strong oil-wet to weak oil-
wet. In this concentration range, quartz sand rejects water, and the contact
angles with respect to water phase are greater than 90 degrees. When the