The impact of constitutive laws on wellbore stability: A general review

This paper is focused on soft deep rocks that can induce strong wellbore-stability problems. In the first part, it is shown that these rocks generally exhibit plastic-type behaviors. In the second part two elastoplastic models (Cam-Clay and Laderock) are briefly presented. In the third part, these constitutive laws are applied to wellbore stability through analytical solutions or finite element codes. Finally, in the fourth part a case history is discussed in detail. We insist on the difficulty to properly define the boundary conditions of the problem (in-situ stresses and virgin pore pressure) and on the subjectivity of the criterion translating the boundary wellbore problem in stability recommendations. Some keys for future research are proposed.