PBS Plug M System is a surface-mixed, pumpable solids-laden slurry, formulated to provide an enhanced rigid crosslinked gel structure after pumping. This system includes sized particles of borate-containing minerals and special polymers, which provide formulating flexibility to accomplish diverse requirements in lost circulation applications. PBS Plug Modifier, a calcium/magnesium compound, and PBS Plug Activator M, a salt/magnesia compound, serve as crosslink catalysts when mixed with PBS Plug M to provide maximum gel structure with reduced setting times. Alternatively, PBS Plug Accelerator is an additional activator for low-temperature applications, or to increase rigidity of the plug. The polymers in the base product enhance viscosity and filtration control and are crosslinked by the borate anion once ionized by the sparingly water-soluble borate salts. The catalysts initiate the crosslink reaction by raising the pH and salinity from a fresh water slurry. This reaction is accelerated by the normally higher temperature in the wellbore. PBS Plug Retarder is used to delay the set, increase the available pumping time on surface, and broaden the window of possible applications. The PBS Plug M System density ranges from 10.3 lb/gal to 18.0 lb/gal, which is achieved with the addition of calcium carbonate, barite or hematite. PBS Plug M System products are packaged in 25 kg sacks.