The purpose of the Wiper Plug and the Drill Pipe Dart is to be a physical barrier between fluids and cement slurries to avoid contamination. To fulfill the separation both components have high quality elastomeric fences for optimal sealing. In addition, the Wiper Plug has an integrated shearable ball seat which catches the Setting Ball for further hydraulic setting operations. After building up the shear pressure for the ball seat, the ball seat is blown into the tube catcher and circulation can be re-established. Accordingly, the system can be cemented.
Once the cementing operation is finished the Drill Pipe Dart is released from the Cementing Head. The dart wipes the drill string and separates the cement from the mud until it lands in a shear sleeve of the Wiper Plug. The shear sleeve and the Drill Pipe Dart have a special latch profile to avoid any movement due to up/down differential pressure after landing. By applying pressure the shear sleeve shears and frees the dogs to release the Wiper Plug. In case of a Double Wiper Plug system the first Dart will be released before cementing operation. This will release the first Wiper Plug which will separate the mud and the cement before it lands in the Landing Collar. After this, the (second) Wiper Plug displaces the cement slurry, wipes the liner and lands in the Landing Collar. Following this, a pressure test for the Liner Hanger can be performed.
To enable an easy drill out operation the Wiper Plug’s and Landing Collar
's anti rotation profiles fit into each other. The Wiper Plug and Drill Pipe Dart components are PDC drillable.