Abstract: A drilling fluid additive sweep cartridge and method. The cartridge contains additives and the cartridge introduces those additives at the tool joint of the next drill pipe used which is positioned in the mouse hole. A modified sweep cartridge introduces the additive in the kelly pipe. Sealing disks in the form of neoprene blowout seals are used to hold the additive inside the sweep cartridge until the seals are partly ruptured by line water pressure. The sweep cartridge is retained inside the tool joint or the kelly pipe by retainers of various designs.