PROCESS DESCRIPTION
If natural gas and petroleum resources can no longer be exploited through natural reservoir pressure (primary production) or by introducing water (secondary production), so-called tertiary processes, known as Enhanced Oil Recovery (EOR) or Enhanced Gas Recovery (EGR), are used. Tertiary processes include the injection of gases into the reservoir. During "fracking" so-called "shale gas" is extracted. Here, aqueous suspensions are injected into rock layers at high pressure, breaking up gas-containing layers so that natural gas is released.