Page 170 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

154 Gas Wettability of Reservoir Rock Surfaces with Porous Media

phase, it is called reverse imbibition (also known as backward imbibition).
The quantity, speed, and efficiency of wetting-phase imbibition is affected by
factors, including the geometrical shape of cores, boundary conditions, wetta-
bility of cores, fluid property, core property, and the interaction of fluids and
cores [24]. Keeping in mind the gas/liquid (water or oil)/rock system, this sec-
tion details experiments on unidirection self-adsorption and reverse self-
adsorption, respectively, studying the effect of gas wettability on imbibition
gas recovery, imbibition speed and saturation of captured gas.

4.4.1 Gas-wetting Alteration of Cores
4.4.1.1 CORE PRETREATMENT

4.4.1.1.1 Imbibition Experimental Procedure
There are many factors affecting the imbibition process. In order to investigate
the effect of gas wettability on core imbibition and eliminate the interference
of other factors, on one hand, cores (air permeability 5 177 6 10 md, and
porosity 5 14% 6 3%) having the same permeability and porosity from the
same batch of artificial cores were used in the imbibition experiment. On the
other hand, under similar experimental conditions, depolarized neutral kero-
sene and deionized distilled water were taken as liquid phase, and air was
taken as the gas phase for the imbibition experiment. The entire experiment
process is displayed in Fig. 4.19.

4.4.1.1.2 Procedure of Core Sample Pretreatment
1. A number of artificial cores were pressed with 60B80 mesh outcrop
sands and silicate cement;
2. Prepared and artificial cores were measured using perm-plug method
with 177 6 10 md permeability;
3. Porosity measurement was conducted on the selected artificial core
using weighing method, and the artificial core with 14% 6 3% porosity
was further selected as the rock sample for the experiment;

FIGURE 4.19
Flow chart of imbibition experiment.