Potassium chloride is used for drilling / drilling fluid in the oil recovery phase. Potassium chloride (KCL) is a soluble salt that is an extremely effective slate stabilizer when drilling water-sensitive clays and slates. Inhibition is provided through ion exchange; the potassium ion enters between the individual clay platelets in the shale, so that they are held together, thus eliminating water from the drilling fluid. Store indoors in a dry climate.