Page 95 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Evaluation Methods and Influencing Factors CHAPTER 2 79

Table 2.17 Effect of Roughness on Gas Wettability (Bubble Capture Method)
Gas-Water System Gas-Oil System
Glass Slide Gas Contact Angle Glass Slide Gas Contact Angle
Number θ gas ( ) Number θ gas ( )

170.1 173.5
W 0 0 O 0 0
W 0 20 167.7 O 0 20 169.7
W 0 40 165.4 O 0 40 167.3
W 0.01 0 168.7 O 0.01 0 171.7
W 0.01 20 162.6 O 0.01 20 166.5
158.4 163.2
W 0.01 40 O 0.01 40
134.2 136.7
W 0.5 0 O 0.5 0
129.9 133.4
W 0.5 20 O 0.5 20
124.7 128.8
W 0.5 40 O 0.5 40
nongas-wettability characteristics (preferential liquid-wetting), as roughness
increases, gas wettability gradually decreases, and gas wettability of solid sur-
face weakens. When the surface of glass slide has preferential gas wettability
characteristics (nonliquid-wetting), as roughness increases, gas wettability
gradually increases, and gas wettability of solid surface is strengthened. Gas
wettability of the surface of glass slide with same roughness treated with HF
acid solution at this stage is gradually strengthened as Zonyl8740 concentra-
tion increases. Gas wettability of glass slide treated with Zonyl8740 solution
of same concentration or having same roughness in gas-water system is
greater than gas wettability in gas-oil system. The above conclusion shows
that gas wettability is related to the form and chemical composition of
solid surface.

2.4.4.2 STUDY OF BUBBLE CAPTURE METHOD

See Table 2.17 for results of gas wettability evaluation of glass slides with dif-
ferent roughness and varying degrees of gas wettability by bubble capture
method in liquid.
From Table 2.17, it can be seen that all contact angles of gas are greater than
90 degrees, and surfaces of all the glass slides have nongas-wettability charac-
teristics. On the surface of glass slide treated with Zonyl8740 solution of same
concentration, as roughness increases, contact angle of gas gradually decreases
and gas wettability is strengthened. On the surface with the same roughness,
as Zonyl8740 solution concentration increases, gas wettability is strengthened
and gas wettability of gas-water system is greater than that of gas-oil system.
Comparing sessile drop method and bubble capture method, it can be seen
that gas wettability of the same solid surface processed with sessile drop
method is greater than that processed with bubble capture method.