A new technique was developed for quantitatively analyzing the effectiveness of shale swelling inhibitors in retarding fluid adsorption and volume expansion. Details of testing procedures, equipment construction, and design rationale are provided. Comparisons are made to methods commonly used in mud labs today, and examples of test results are given to illustrate the new technique's usefulness and versatility. Relevant concepts of clay hydration theory are discussed to provide background for interpreting the presented experimental results. Differentiation between crystalline swelling, and combined crystalline and osmotic swelling is achieved by applying a mechanical restraining force (preload) to shale samples while being hydrated. Mud additives examined include various salts, ferrochrome lignosulfonate, and several polymers.

Keywords:
particle, laboratory technique, interaction, hydration, preload, concentration, hydration energy, drilling fluid selection and formulation, polymer, chemical interaction
Subjects:
Drilling Fluids and Materials, Drilling fluid selection and formulation (chemistry, properties)
Copyright 1982, Society of Petroleum Engineers of AIME
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