The test for high potassium ion
concentration was first applied to drilling fluids by Ron Steiger at Exxon Production Research Co. and has proven to be a reliable way to measure K+ ion concentration in a mud at the wellsite, which allows the mud engineer to maintain the
proper level when drilling through hydratable shales. Before a direct test for K+ ion was available, KCl in a mud was monitored by chloride analysis. Although simple to perform, this analysis was misleading and counterproductive because after
drilling shale with a new KCl mud for awhile, the beneficial K+ ion was consumed by the clays but the Cl- ion remained in the mud. Eventually, the wellbore shales hydrated, fell into the hole and created severe mud and drilling
problems. As a result of improper analytical methods, early potassium muds earned an undeservedly negative reputation.
For optimal shale stability, K+ ion must be continually maintained by adding KCl (or some other K salt) as fast as it
is consumed. The advent of a direct field-worthy method for K+ analysis, the result of Dr. Steiger's efforts, was a breakthrough in the use of water mud for drilling troublesome shale.Reference:Steiger RP: "Fundamentals and Use
of Potassium/Polymer Drilling Fluids to Minimize Drilling and Completion Problems Associated with Hydratable Clays," Journal of Petroleum Technology 34, no. 8 (August 1982): 1661-1670.