shown coupled to the wiper plug 20 the perforating system 24 comprises a perforating gun 26 with shaped charges 27 for creating perforations 29 through the casing 7 and into the surrounding formation 9 in the embodiment shown a line 22 couples the perforating gun 26 to the wiper plug 20 an optional wireline 28 may be used to deploy the perforating gun 26 into the wellbore 5 and to convey an initiation signal for detonating the shaped charges 27 the wireline 28 can also be used to remove the perforating gun 26 from the wellbore 5 however as discussed below the perforating gun 26 can also be free floating in the wellbore 5 attached to a wiper plug 20 without being suspended from a deployment member such as a wireline 28 additionally the shaped charge 27 detonation signal may be from a timer circuit telemetry or other communication means after shaped charge 27 detonation the gun 26 can remain in the wellbore 5 or retrieved using fishing techniques a fishing neck not shown may be included on the perforating gun 26 for later retrieval to ensure the perforating gun 26 can be detached from the wiper plug 20 a frangible link may be included in the connection between the perforating gun 26 and the wiper plug 20 alternatively the coupling between the perforating gun 26 and the wiper plug 20 may include a detachment mechanism automatically activated upon shaped charge 27 initiation after a programmed delay or manually on a command from the surface in one mode of operation of the embodiment illustrated in fig2 a typical cementing operation may take place by applying completion fluid 15 from an injection system 30 to the upper or high pressure side of the wiper plug 20 alternatively the substance added into.