Evaluation of Reactive Clay in Indian Shale

Shale formations are composed of clays, feldspars, carbonates, and quartz as major ingredients. Among all the constituents, clays are the most important parameter from an application point of view because of their possibly sensitive nature; they are further categorised as migrating (illite, kaolinite, and chlorite) and reactive (smectite and mixed layers) clays. Smectite is always considered as reactive clay, and it appears in shale as an individual phase or as a component of mixed layer clay. This article outlines the laboratory methods used to measure the concentration of reactive clay minerals in shale and their controlling parameters. The process includes analysis of samples by X-ray Diffraction (XRD), Cation Exchange Capacity (CEC), and Capillary Suction Time (CST) tests. The samples used for the study include shale samples from Indian origin. The data obtained from each method are reported, including the effect of brines for inhibiting clay reactivity.