Page 174 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

158 Gas Wettability of Reservoir Rock Surfaces with Porous Media

FIGURE 4.23
Diagram of imbibition experimental facilities.

solutions of the same concentration. The faces are sealed with a sealing tape
and placed in a constant temperature and humidity chamber hanging on a
scale (60.001 g) for self-water-adsorption and self-oil-adsorption experiments.
The scale translates the changes in core mass in the imbibition process into
electrical signals to a computer through a tension sensor; the computer records
the dynamic imbibition capacity of cores in real time and processes data stor-
age and analysis. The imbibition gas recovery (self-water-adsorption gas recov-
ery: S gas-water , and self-oil-adsorption gas recovery: S gas-oil ) is calculated using
formula (4.11) and formula (4.12).
As displayed in Fig. 4.23,
The gas recovery of the cores’ unidirection imbibitions is calculated using for-
mula (4.1) and formula (4.2).
M water
Water 2 gas 2 rock system: S gas-water 5 ð1 2 Þ 3 100% (4.11)
ρ water V
M oil
Oil 2 gas 2 rock system: S gas-oil 5 ð1 2 Þ 3 100% (4.12)
ρ V
oil
In the formula, S gas-water — unidirection self-water-adsorption recovery, %;
M water —unidirection self-water-adsorption mass, g; ρ water — density of water,
3
3
g/cm ; V—pore volume of cores, cm ; S gas-oil —unidirection self-oil-adsorption
recovery, %; M ʹ —unidirection self-oil-adsorption mass, g; ρ oil — density of oil,
3
g/cm .
At the beginning of the experiment, the liquid was injected from the intake
pipes. When the liquid level in cups was tangential to the bottom of the cores,
the scale was reset. At the same time, the imbibition treatment software was
started to collect and process data. In order to reduce the interference of exter-
nal factors, the experiment was conducted in a sealed environment (tempera-

ture: 25 C, humidity: 75%).