Page 201 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Effect of Gas Wettability on Capillaries CHAPTER 5 185

(A) (B)

(C)
FIGURE 5.18
Effect of gas wettability on gas/oil distribution and gas recovery. (A) Nongas-wettability, (B) neutral-gas-wettability, and (C)
preferential-gas-wettability.

5.3.1 Effect of Core Permeability
5.3.1.1 SCREENING OF CORES

The effect of wettability on the displacing effect of cores was studied by screen-
ing cores with similar physical properties.
1. Cores were washed with Soxhlet extraction and organic solvent (see
Fig. 5.20), and baked before weighing;
2. The permeability of washed and dried cores was measured. Permeability
was measured thrice in intervals of 10 minutes each, while constant dif-
ferential pressure was applied to the two ends of the cores. The average
value of all three was taken as the gas permeability of the core ðK g Þ;
2
3. Cores with gas permeability of (1500 6 10) 3 10 23 μm were selected.
The selected core was saturated with distilled water using vacuum
pumps, and was then weighed. The porosity of cores ðφÞ was calculated
using the weight method;
4. Cores with porosity of (35 6 5)% were marked numerically in order
(see Table 5.1), and baked for application.

5.3.1.2 DISPLACEMENT EXPERIMENT
5.3.1.2.1 Pretreatment of Cores
1. Flourocarbon polymer gas-wetting alteration agent solutions of 7% and
15% concentration were prepared.
2. One core column was cut into six pieces of 1.5 cm thickness each.