US Patent 12116862 Dual detached wiper plug system for cementing operation

A cementing string assembly for cementing a liner in a wellbore includes a drill pipe, a liner hanger running tool attached to the drill pipe, a liner releasably secured to the liner hanger running tool, an upper wiper plug disposed within the liner and releasably secured to the liner hanger running tool or to the liner, and a lower wiper plug disposed within the liner and releasably secured to the liner downhole of the upper wiper plug. The lower wiper plug is detached from the upper wiper plug. The lower wiper plug is releasably secured to an inner surface of the liner by a wiper plug hanging collar and is releasable from the liner independent of the upper wiper plug and without exerting forces on the upper wiper plug. The cementing string assembly prevent premature and unintentional release of the upper wiper plug while releasing the lower wiper plug.