Keynote Speakers

Sunday, 25 June
MTS Lecture

Vertical Stress Profiles and the Long-term Rheology of Rock Masses

François Henri Cornet, Professor Emeritus, Institut de Physique du Globe de Strasbourg, France

The classical hydraulic fracturing method together with its various extension techniques provide very efficient means for determining in situ the complete stress tensor at various depths. When combined with focal mechanisms of induced seismicity, it may even be used to map spatial variations of pore pressure. The discussion of such a vertical stress profile, as obtained in the French Paris Basin sedimentary formations, will help us outline the importance of visco-elasticity on stress. In particular, it will help us demonstrate the role of pressure-solution on the local present-day stress field. This may have strong consequences for a better control of induced seismicity and more generally for the understanding of intraplate seismicity.

To read biographical sketch, CLICK HERE


Monday, 26 June
Keynote Address

Seismicity-Permeability Coupling in Reservoirs and Caprocks

Derek Elsworth, Professor, Departments of Energy and Mineral Engineering and Geosciences, G3 Center and EMS Energy Institute, Pennsylvania State University, University Park, USA

Contemporary methods of energy conversions that reduce carbon intensity include sequestering CO2, fuel switching to lower-carbon sources, such as from gas shales, and recovering deep geothermal energy via EGS. In all of these endeavors, either maintaining the low permeability and integrity of caprocks or in controlling the growth of permeability in initially very-low-permeability shales and geothermal reservoirs represent key desires. At short-timescales of relevance, permeability is driven principally by deformations – in turn resulting from changes in total stresses, fluid pressure or thermal and chemical effects. These deformations may be intrinsically stable or unstable, result in aseismic or seismic deformation, with resulting changes in permeability conditioned by the deformational mode. We report experiments and models to represent the respective roles of mineralogy, texture, scale and overpressures on the evolution of friction, stability and permeability in fractured rocks, and their consequences on fluid production, containment and induced seismicity.

To read biographical sketch, CLICK HERE


Monday, 26 June
Early Career Keynote Address

Stress and Pressure in Mudrocks Bounding Salt Systems 

Maria Nikolinakou, Research Associate, Bureau of Economic Geology, University of Texas, Austin, USA

We study the evolution of stress and pore pressure in mudrocks that bound salt systems. Our evolutionary geomechanical models couple deformation with sedimentation and porous fluid flow. We find that high differential stresses arise near rising diapirs and below salt. We show that salt emplacement induces significant excess pressures that are comparable to the weight of the salt sheet. In addition, we show that the shear-induced component of the excess pressures is significant. We also find that low effective stresses result in low strength, which enables salt growth. We model salt as solid viscoplastic and sediments as poroelastoplastic materials, and calibrate the consolidation properties based on experimental testing on smectite-rich mudrocks typical of those in the Gulf of Mexico. There is very limited published application of transient models in the energy industry. We illustrate that our approach can be applied to design stable well bores as well as to provide insight into macroscale geologic processes. Overall, we show that transient evolutionary models can predict stress and pore pressure in many geologic systems where large strains, pore fluids, and sedimentation interact.

To read biographical sketch, CLICK HERE


Tuesday, 27 June
Keynote Address

Integrating Geomechanics into Unconventional Resource Development

David Yale, ExxonMobil (Ret.)


Wednesday, 28 June
Keynote Address

Twenty-five Years of Seismic Tomography for Mine Rockmass Monitoring 

Erik Westman, Professor, Mining and Minerals Engineering Department, Virginia Tech, Blacksburg, USA 

 

This talk will describe case studies where seismic tomography has been used to better understand stress redistribution in underground mines.  Examples from both coal and hardrock mines will be shared.  Results show that this tool can complement existing tools (such as point-location geotechnical monitoring and numerical modeling) to help the engineer better design safe and efficient operations.

To read biographical sketch, CLICK HERE