During a well drilling operation, cement casing is typically inserted into the borehole to provide structural support for the borehole in unstable geological formations in addition to sealing the borehole. The casing is typically cemented in place by circulating a cement slurry through the inside of the casing and out into the annulus through a casing shoe at the bottom of the casing string. To prevent the cement from flowing back into the inside of the casing, a float collar above the casing shoe may be used to act as a check valve and prevent the fluid from flowing up through the shoe from the annulus.
After an initial casing is inserted and cemented into the borehole, another smaller casing may be inserted with a liner hanger on a running tool and cemented into the borehole in a similar fashion. This may continue downward into the borehole in a telescoping fashion as the inserted casings become progressively smaller diameter.
The running tool, with a plug system coupled to the bottom, holds the liner casing as the running tool descends through the borehole. The downhole environment may include multiple downhole tools, having central bores, that are part of the casing. Similarly, conventional wiping plugs of the plug system have a central bore through which fluid flows. Additionally, multiple conventional plugs are used from the surface to the toe of the well due to the diameter changes between the drill pipe and liner hanger setting tool, and the casing in the liner. The use of these conventional plugs limits the quantity of sleeve tools possible within the liner casing due to the larger diameter of the plug used to wipe the cement.