The wiper plug system is an essential component of well cementing operations. Installed on the cement head, these plugs ensure efficient displacement of cement into the casing by:
Separating fluids (mud, spacer, cement, displacement fluid),
Cleaning the casing interior, and
Preventing contamination between fluids.
Cementing Sequence Using Wiper Plungs
- Bottom Plug
Loaded into the cement head first.
Pumped ahead of the cement slurry.
Wipes drilling mud from the casing walls.
Ruptures when it seats on the float collar, allowing cement to pass through.
2.Cement Slurry:
Pumped immediately after the bottom plug.
Flows downhole behind the bottom plug and into the annulus.
- Top Plug
Launched after all cement is pumped.
Separates cement from the displacement fluid (usually drilling mud or water).
When it lands on the bottom plug, a pressure spike is observed — indicating cement displacement is complete.
Cement Head Configuration
A cement head is mounted on top of the casing and typically holds:
One or two wiper plugs (in chambers),
Valves and ports for injecting cement,
A quick-latch system for safe plug release.
Some cement heads are double-plug systems with two separate compartments for launching both top and bottom plugs automatically or manually.
Benefits
Maintains cement integrity by avoiding mixing with mud.
Ensures clean casing ID for better cement bonding.
Pressure response gives operators a clear signal of placement success.