|The pore space
(void space inside the rock, picture a hard sponge) in the
formations at several thousand feet of depth in the vicinity of
disposal wells are already 100% saturated with natural brines.
In many injection zones, these brines have specific gravities
of between 1.05 and 1.2 gm/ml.
This salinity can be several times the salinity of seawater.
When operated, Class I wells have fluid inside the tubing
from the surface all the way down to the injection zone.
By adding a carefully controlled amount of pressure to the
fluid by pumping during disposal operations, wells can be used to
add the injectate to the brine already present in the injection
formation. This is accomplished by pushing natural fluids out of the
rock pore spaces near the well and into neighboring pore spaces by
compressing these moving fluids and the fluid already contained
inside those rock spaces to a higher pressure. This effect continues
radially away from the well.