Page 216 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

200 Gas Wettability of Reservoir Rock Surfaces with Porous Media

Table 6.3 Core Contact Angles and Surface Energy (After FCS-08
Adsorption Equilibrium)

Concentration Contact Angle ( ) Surface Energy (mN/m)

(%)
Distilled n- Dispersion Polarity Surface
Water Hexadecane Force Force Energy
0.1 101.25 63.75 14.35 2.64 16.99
0.2 115.00 70.25 12.35 0.42 12.77
0.3 120.50 73.25 11.45 0.09 11.54
0.4 122.75 75.50 10.79 0.04 10.83
0.5 123.25 76.00 10.64 0.03 10.67
0.6 124.00 80.50 9.37 0.06 9.43
0.7 124.25 81.25 9.16 0.06 9.22
0.8 123.75 82.50 8.82 0.10 8.92
0.9 123.50 84.75 8.22 0.17 8.39
1.0 124.75 85.00 8.16 0.11 8.27

concentration increased, the contact angles of water and oil phases gradually
enlarged. The contact angle of distilled water on the surfaces of treated cores
was a maximum of 124.75 degrees, and the contact angle of n-Hexadecane
was 85.00 degrees. The surface energy was reduced to 8.27 mN/m, which is far
below the surface tension of normal liquids. So, it is difficult to be wetted by
liquids. The above results indicate that adsorption of FCS-08 occurs on the
surface of core slices. The stable adsorption film makes the core surface hydro-
phobic and oleophobic. This effectively reduces the liquid phase adherence on
the core surface, enhances the flow capability, reduces capillary pressure, and
prevents damage from water-blocks. When the concentration of FCS-08 was
greater than 0.4%, the tendency of the contact angle to enlarge gradually
slowed down.

6.1.3 Preparation and Properties of Film-Forming
Polymer Oil Protection Agent LCM-8
6.1.3.1 PREPARATION OF LCM-08
Purified styrene (St), butyl acrylate (BA), and reactive polymer emulsifier were
added to 150 mL of deionized water to conduct emulsification pretreatment.
It was then transferred to a four-mouth flask mounted with nitrogen input
devices and reflux condensate devices. The temperature of the water bath was
set at 80 C, and the water-soluble initiator was dipped in twice, after stirring.

The reaction completed after 6 hours.
The solution obtained was added in a macrobridging agent and microbridging
agent at a certain proportion. The final production was a milky white viscous
liquid, which was prepared with a film-forming polymer drilling liquid addi-
tive LCM-8 (Fig. 6.1). The grain diameter distribution is as shown in Fig. 6.2.