Page 222 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

206 Gas Wettability of Reservoir Rock Surfaces with Porous Media

100
Plugging rate
90 Recovery rate
80
70
60
50
40
30
20
10
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14
FIGURE 6.8
Permeability damage rate bar chart after rock samples are polluted by the formulations.

water-block resistance agent FCS-08, and the acrylate polymer-based oil pro-
tection agent LCM-8, is higher than that caused by other film-forming drilling
fluid systems. Furthermore, when the LCM-8 content in the drilling fluid sys-
tem is greater than 2%, it can increase the permeability plugging rate to 90%.
However, when the concentration is greater than 2%, the permeability plug-
ging rate increases a little. Therefore, when the concentration of LCM-8 is 2%,
the permeability of the pollution end can be greatly reduced to prevent
drilling fluid filtrate from further invading the interiors of the reservoirs.

6.1.4.2 EVALUATION OF PERMEABILITY RECOVERY
To further study the protecting reservoirs effect of fluorine-containing water-
block resistance agent FCS-08 and the acrylate polymer-based oil protection
agent LCM-8, the above rock samples were sliced and the oil-phase perme-
ability recovery of remaining rock samples were measured, as shown in
Fig. 6.9.

It can be seen from the research results that when the polluted end is cut off, the
permeability recovery values of all rock samples show an obvious increase.
A shielding ring with extra-low-permeability forms within a short distance from
the pollution end, so that the solid-phase grains and filtrate of the drilling com-
pletion fluids are completely blocked from accessing the reservoirs, thereby pro-
tecting the reservoir. At the same time, the permeability recovery values of other
film-forming agent systems are all less than the FCS-081 LCM-8 system. This
illustrates that when the water-block resistance agent FCS-08 enters the rock sam-
ples through instantaneous filtration, it forms thin films on the pore surface of