A cementing method includes positioning a bottom plug at a casing shoe, rupturing the bottom plug, signaling when a top plug reaches a target position, and releasing a chemical into a cement slurry below the top plug in response to the signaling. The signal may comprise a mechanical trigger changing its position due to movement of the top plug past the target position.
Cementing methods and systems employing a smart plug
Gupta, V., Roberson, M., Myers, D. F., Davis, J. L., & Dausch, D. E. (2019). Cementing methods and systems employing a smart plug. (U.S. Patent No. 10,196,308 B2).