Testing study on the hydration of shale

Borehole stability problems are always the concern during drilling through shale formations. The stress redistribution is induced near the wellbore when interaction occurs between shale formation and water-based drilling fluid. The primary testing study is made on hydration of shale under non-volumetric strain conditions with the triaxial test system of rock mechanics. Testing results show that swelling occurs not only in horizontal direction but also in vertical direction. Swelling pressure would go up quickly in a short period after being exposed to water followed by a linear increment with time.EI0SUPPL.910-9121