Strength Characteristics of Rock Samples Under Hydrostatic Pressure

• Published in: Journal of fluids engineering 1957-05, Vol.79, p.695-706
• Main Author: Bredthauer, R. O
• Format: Article
• Language: English
• ISSN: 0098-2202; 1528-901X
• DOI: 10.1115/1.4013134

Other investigations have shown that rock cylinders exposed to hydrostatic pressures of 10,000 atm and loaded axially in compression behave in a ductile fashion as contrasted with their brittle behavior when tested in axial compression at atmospheric pressure. Similar tests were made by the author on rock cylinders in the pressure range 0 to 15,000 psi, which is equivalent to pressures exerted by drilling muds upon the face of formations exposed to the cutting action of rock-bit teeth. Results indicated that many formations commonly encountered in drilling operations undergo a brittle-to-ductile behavior transition in the range 0 to 15,000-psi hydrostatic pressure. The great majority of tests were made on samples which were dry and which were protected from the surrounding fluid with a plastic jacket. At atmospheric pressure, all formations so tested were brittle. The compressive strength of all formations tested in this condition increased with increasing confining pressure.