Characterization of crack formation and development in the oil&gas well casing cement sheath

Abstract

The oil industry relies on the use of cement as a primary barrier, to isolate the steel casing from the surrounding formations and provide overall stability on the bored structure. There has been extensive technological development on the physical and mechanical properties of the materials from the cement and cementing industry, in order to produce and install effective cement barriers, capable of withstanding both physical and chemical loads under extreme wellbore conditions. In particular, the formation of cracks and interfacial damage at the primary cement sheath is a largely discussed issue. However, there is still a limited understanding about the crack formation and propagation processes in well-cements, due to the particular geometric and boundary conditions of the structural system, such as: pressure, temperature, and confinement conditions. This paper is focused on the crack formation and propagation processes on cement systems under wellbore-like geometrical conditions, and proposes a test-setup to evaluate cracking and localized damage at the casing-cement interface.