US Patent 8127846 Wiper plug perforating system

A method and system for cementing and perforating a wellbore in a single step by coupling a perforating gun with a wiper plug. The method includes injecting cement in a wellbore having casing therein and an annulus between the casing and wellbore. A wiper plug is dropped on the cement having a perforating gun attached to the wiper plug. The plug is forced downward pulling the perforating gun along. The downward motion of the plug in turn pushes the cement out the bottom end of the casing and into the annulus. The cement in the annulus is allowed to set and the perforating gun is activated.