Flow Control Packer (FCP)
The simplest method allowing basic unmanned and unmonitored control of the injection process is to employ a pneumatic packer at the bottom of the injection column or simply suspended into the bore casing.
The packer is inflated with air or nitrogen to a specific pressure such
that injection pressure by means of the gas 
compressibility
automatically inflates and deflates the packer to control the injection
pressure and thus injection flow rate. This system does not allow
manual operation of the down hole valve or control of specific injection
flow rates. It simply maintains a given injection head pressure by
varying the injection flow rate.
If the injection head is not sufficient, the packer will remain fully
inflated allowing no injection flow. When the injection head increases
due to water supply etc, the head pressure on the packer builds and
automatically compresses the inflation gas causing the packer to
partially deflate. The amount of head pressure in the system will
determine the amount of packer deflation and hence injection flowrate.
When the injection head falls, the packer will automatically start to
re-inflate dropping the injection flow rate to maintain the minimum
required column head.
