Page 241 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Application of Gas Wettability CHAPTER 6 225

5 4

Permeability 10 –3 µm 2 3 2 Before injecting trapezoid protection agent After injecting trapezoid protection agent

0 1
20 30 40 50 60 70 80 5 10 15 20 25 30 35 40
Volume pumped in pores PV
FIGURE 6.16
Experimental results of damage due to adsorption of trapezoid protection agent A on rock surfaces.

5 4

Permeability 10 –3 µm 2 3 2 Injecting modification water and permeation

0 1
5 10 15 20 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400
Volume pumped in pores PV
FIGURE 6.17
Experimental results of antiswelling period with trapezoid protection agent A.

permeability of cores does not decrease, which solves the problem of damage
to water-sensitive reservoirs by injected water. Trapezoid protection agent A
can be used as the protection agent to prevent damage to low and extra-low-
permeability reservoirs.

In order to investigate the effects of reservoir protection offered by trapezoid
protection agent A, a KCl antiswelling cycle evaluation was conducted. The
experimental core was taken from S2 upper layers of S56-10 well, in Shengli
Oilfield. The evaluation result is shown in Fig. 6.18.
It can be seen from the experimental data that when the core is treated with
KCI and modification water is injected, the permeability of cores decreases by
25.5% within 20 PV. Then, it is balanced until 400 PV, and there is no longer
any change.