US Patent 7861781 Pump down cement retaining device

A wall casing cement plug assembly includes a receptacle with an axial passage. The receptacle is pumped to a lower end of the casing string and locked in place. The receptacle has a casing seal that engages the string of casing and a retainer mechanism on its exterior that engages a profile in the string of casing. Cement is pumped through the receptacle by rupturing a blocking device in the axial passage of the receptacle. A wiper plug is pumped down the string casing. The wiper plug has a prong on its lower end that stabs into the axial passage of the receptacle. A latch located in the lower portion of the receptacle locks the wiper plug to the body.