Cementing Plug: when the drilling fluid make the bottom plug move into the end, raised plum flower petal of the bottom plug’s lower end engaging with the hollow plum flower petal of float collar’s upper end. At the same time, the pressure rise, when reach the definite pressure, the burst disk in the bottom plug crush, the passageway open, and the pump pressure descent, at this time can cementing.
After cementing, pumping into the top plug to clean cement slurry on the inner wall, the raised plum flower petal of the top plug engaging with the hollow plum flower petal of the bottom plug.
