INTRODUCTORY KEYNOTE LECTURE
Coupled THMC Processes in Fractured Rocks: Looking Backward and Seeing Forward
Lawrence Berkeley National Laboratory, USA; Uppsala University, Sweden
Chin-Fu Tsang received his B.Sc. first class honour degree in Physics in 1964 from the University of Manchester in UK and his PhD in 1969 from the University of California Berkeley in US. He spent his entire research career with Lawrence Berkeley National Laboratory, retiring in 2005 as Senior Scientist Emeritus in the Earth Sciences Division. Since retirement, he has continued his research first as a visiting professor of hydrogeology at Imperial College London in UK and then as a visiting professor and visiting scholar at Uppsala University in Sweden. He was also the founding chairman of the DECOVALEX project, serving as its chairman from 1992 to 2007.
Introduction of the Lecture
The study of coupled thermo-hydro-mechanical-chemical (THMC) processes in fractured rocks was identified as an important area of scientific research in the 1980’s, initially in the safety assessment of nuclear waste geological repository. It was then recognized as a crucial component of other geotechnical projects, such as enhanced geothermal energy development, fracking in unconventional gas development and waste water injection disposal, with related induced seismicity. Sustained efforts over the last decades cover a wide range of research topics, including fundamental studies, laboratory investigations, numerical model developments, field scale experiments and modeling. A typical example is the multinational cooperative research project DECOVALEX, that was initiated in 1992 and is still on-going with active participation of twelve countries. The present lecture will provide a look to the past years in this research field to review “where we have come from” and a discussion on some of the major challenges facing us today. These challenges include the role of natural fractures network at different flow percolation levels in hydromechanical processes, the interaction of flow bottlenecks and stress concentration points in fractured rocks, and changes in flow channeling effect due to mechanical deformation and chemical precipitation and dissolution.