The Separation of Electrolyte Effects From Rheological Effects in Studies of Inhibition of Shales With Natural Moisture Contents

Abstract

ABSTRACT The shale rolling test is a common procedure that is used to measure the interactions between drilling fluids and shales. This study found that the results of the shale rolling test depend on the moisture content of the shale, the shale composition, the viscosity of the test fluid, the rotation speed of the rollers, and the test temperature. To obtain reproducible results, all of these variables must be carefully controlled. The rheological behavior of the test fluid has the strongest influence on test results. This led to the conclusion that the rolling test is only valid for unviscosified drilling fluids. This severely limits the applicability of the test. Drying the shales caused changes that influenced test results. This indicates that, when possible, tests should be run with shales of native moisture content. When test variables are carefully controlled, the rolling test is a useful technique to measure the interactions of electrolytes with shale granules in partially formulated drilling fluids.