Events

Dr. Robert Zimmerman, Professor at the Department of Earth Science Engineering at Imperial College, will be presenting on "A Fully-Triaxial and Anisotropic Model for Borehole Stability Analysis in Shales".

Abstract:

Many reservoir rocks, such as shales, exhibit anisotropy in their elastic and strength properties. Nevertheless, stability analysis of boreholes drilled into anisotropic formations is often conducted using isotropic models for computing the near-borehole stresses. Furthermore, although it is known that the intermediate principal stress has an effect on shear failure, borehole stability analysis is often carried out using failure criteria that ignore the intermediate stress. In this talk, I will discuss a new model for borehole stability in anisotropic formations.

In this model, the borehole stresses can be computed using either the Hiramatsu-Oka solution based on isotropic elasticity, or using the Lekhnitskii-Amadei anisotropic elasticity solution. Shear failure along the borehole wall is modeled using two variants of the Jaeger plane of weakness model, which make use of either the Mohr-Coulomb or the (true-triaxial) Mogi-Coulomb failure criterion for failure through the “intact rock” - i.e., failure along planes other than a bedding plane.

About Dr. Zimmerman:

Robert Zimmerman obtained a BS and MS in mechanical engineering from Columbia University, and a PhD in continuum mechanics from UC Berkeley. He has been a lecturer at UC Berkeley, a staff scientist at the Lawrence Berkeley National Laboratory, and Head of the Division of Engineering Geology and Geophysics at the Royal Institute of Technology in Stockholm. He is the Editor-in-Chief of the International Journal of Rock Mechanics and Mining Sciences, and serves on the Editorial Boards of Transport in Porous Media and the International Journal of Engineering Science. He is the author of the monograph Compressibility of Sandstones (Elsevier, 1991), co-author, with JC Jaeger and NGW Cook, of Fundamentals of Rock Mechanics (4th ed., Wiley-Blackwell, 2007), and author of the textbook Fluid Flow in Porous Media (World Scientific, 2018). He is currently Professor of Rock Mechanics at Imperial College, where he conducts research on rock mechanics and fractured rock hydrology, with applications to petroleum engineering, underground mining, carbon sequestration, and radioactive waste disposal.