1962 Paper A

LABORATORY RESISTIVITY EVALUATION OF LIME, GYP, AND CALCIUM LIGNITE-CALCIUM LIGNOSULFONATE MUDS

G. C. Wang - The University of Tulsa D. P. Helander - The University of Tulsa D. R. Wieland - The University of Tulsa

ABSTRACT

Resistivity measurements of the mud, mud filtrate, and mud cake were obtained over a temperature range of 70°F to 190°F for lime, gyp, and calcium lignite-calcium lignosulfonate (CL-CLS) muds of various concentrations. The measurements were made utilizing the Jersey resistivity cell in which mud cake can be measured in situ. The measurements were made after two days of hydration and again after 26 more days of hydration. The results indicate that the values of Rm, Rmf and Rmc do not vary with temperature as sodium chloride solutions, and therefore appreciable error may be incorporated into an interpretation if the mud, mud filtrate, and mud cake are assumed to act as sodium chloride solutions. For lime and gyp muds Rm and Rmf vary with temperature in the same manner while Rmc varies differently. Rmf and Rmc were found to vary similarly for the CL-CLS mud with Rm varying in a different manner. No significant change was measured for Rm, Rmf, or Rmc when the lime content of a lime mud was 5 lb/bbl or more and the gyp content of a gyp mud was 2 lb/bbl or more. The hydration effect after a two-day aging period on the measured resistivity values was found to be small.