Page 230 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

214 Gas Wettability of Reservoir Rock Surfaces with Porous Media

6.2.2.2 BUBBLE ADHESIVENESS
To prove that FGC-1 alters wettability and results in bubbles attaching on cut-
ting surfaces, a contrasting experiment was conducted with two kinds of com-
mon surfactants and FGC-1. At room temperature, 3 flasks with magnetic
rotors were chosen and 40 g of rock cuttings were added, respectively.
Surfactant 1, 2, and FGC-1 at a certain concentration, and the foaming agent
in moderate amounts were prepared in advance. The magnetic stirring appara-
tus was then initiated. It was let to stand for some time when the bubbles are
injected constantly for 5 minutes. The experimental results are shown
Fig. 6.11. In the beginning, a few bubbles are seen attached on the cutting sur-
faces in the flask that had a common surfactant added to it. After a while,
almost no bubbles are attached on the cutting surfaces. However, several bub-
bles adhere to the cutting surfaces in the solution where FGC-1 is added. This
is because FGC-1 is composed of two polarity ends and two nonpolarity ends.
It is easier for the polarity end to be adsorbed on the cutting surface, but the
nonpolarity end is adsorbed on the bubble surface. The rotation of the mag-
netic rotor drives the movement of cuttings in the flasks. As the bubbles are
constantly injected into the flasks, the moving cuttings and bubbles collide
and adhere together. In addition, the foaming agent enhances the strength of
bubbles, making it tougher to break them. The cutting carrying micro-function
mechanism is shown in Fig. 6.12.

6.2.2.3 OPTIMIZING CONCENTRATION AND GRAIN DIAMETER
To investigate the optimum concentration of cutting carrying agent FGC-1 and
the optimum portable grain diameter of cuttings, FGC-1 water solutions were
prepared in different concentrations and sufficient foaming agent was added.
The core was made into rock cuttings with grain diameters of 2.8B3.2,
2.0B2.8, 0.9B2.0, and 0.45B0.90 mm, and the experimental results are
shown in Fig. 6.13.
Bubbles adhere on the surface of rock cuttings, which float on the solution’ssur-
face due to buoyancy. The rock cuttings with grain diameter of 0.9B2.0 mm
easily adhere together with bubbles and are carried with the liquid surface into

FIGURE 6.11
Comparison of bubble adhering effects.