ARMA U.S. Rock Mechanics Association




Program/Keynotes

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Interdisciplinary

Mining

Civil

Petroleum

Keynote Speakers

MTS Lecture
Sunday, 28 June

Thermo-Poro-Mechanics of Shear Localization in Rapidly Sheared Granular Rock and Implications for Earthquake Source Physics


Professor James R. Rice
Mallinckrodt Professor of Engineering Sciences and Geophysics
School of Engineering and Applied Sciences and the
Department of Earth and Planetary Sciences
Harvard University

Field observations of mature, well-slipped, earthquake fault zones show that the majority of shear is often localized to principal slipping zones of order 10-100 microns width within a broader gouge layer of order 10-100 mm wide (with all that being a feature located within a much broader, 1-10s m wide, damage zone bordering the fault). Such fault gouges are often rate-strengthening, especially at higher temperatures, and are then resistant to shear localization under typically slow laboratory deformation rates. Extreme localization is, instead, a predicted consequence of rapid straining, with related shear heating, for realistically fluid-infiltrated gouge on time scales that are too short for significant fluid drainage or heat conduction. Localization is due to development of highly elevated pore pressure. Results are presented for two versions of the process: In the classical one, the pore fluid pre-exists in the gouge as groundwater. In another, thermal decomposition reactions in hydrated silicates (clays, serpentines) or carbonates within gouge are triggered as temperature rises, releasing a volatile phase (H2O or CO2) at high pressure. Results have implications for the mode of slip-rupture propagation in earthquakes (self-healing vs. crack-like) and shed new light on why statically strong faults like the SAF can produce large ruptures with negligible localized heat outflow and with little evidence of melt formation at least in the shallow to middle crust.

To read biographical sketch, CLICK HERE

Monday, 29 June

Some Thoughts on Rock Mechanics in the Oil and Gas Industry


Kate Hadley Baker
BP (ret) and ExxonMobil (ret)

Oil and gas comprise between 50-60% of primary energy demand and are expected to do so for at least the next 25 years. In 2014, the worldwide oil and gas industry produced 93 million barrels of oil and hydrocarbon liquids per day, supplied 325 billion cubic feet per day of natural gas, drilled 83,000 wells and invested USD 1 trillion in capital projects. Rock mechanics is essential in most phases of oil and gas activity, including: exploration and appraisal, development, production, and even well abandonment at the end of asset life. 

In exploration, rock mechanics – or more generally, geomechanics – informs predictions of trap and seal. In exploration and appraisal, knowledge of the mechanical properties of rocks with their contained fluids is essential in interpreting surface seismic and borehole geophysical and petrophysical measurements. The influence of natural fracture networks on production increases as the matrix permeability of the target reservoir decreases and may need to be considered in development planning. In development and production, pore pressure prediction and wellbore instability issues account for more than a third of drilling non-productive time. Optimally designing wells and safely drilling, completing and abandoning them requires knowledge of rock mechanical properties, in situ stresses and pore pressure. Occasionally, compaction or tectonic movements can affect production infrastructure over the field life. Mitigation measures are possible, but expensive. Selected examples from the author’s experience illustrate these concepts.

To read biographical sketch, CLICK HERE

Tuesday, 30 June

The Science of Empirical Design in Mining Rock Mechanics

Christopher Mark, Principal Roof Control Specialist,
Mine Safety and Health Administration (MSHA)

Many problems in rock mechanics are limited by our imperfect knowledge of the material properties and failure mechanics of rock masses. Mining problems are somewhat unique, however, in that plenty of real-world experience is generally available and can be turned into valuable experimental data. Every pillar that is developed, or stope that is mined, represents a full-scale test of a rock mechanics design. By harvesting these data, and then using the appropriate statistical techniques to interpret them, mining engineers have developed powerful design techniques that are widely used around the world. Successful empirical methods are readily accepted because they are simple, transparent, practical, and firmly tethered to reality.

The speaker has been intimately associated with empirical design for his entire career. But where his past papers have described the application of individual techniques to specific problems, the focus of this lecture is the process used to develop a successful empirical method. A six-stage process is described:

  1. Identification of the problem, and of the end users of the final product;
  2. Development of a conceptual rock mechanics model, and identification of the key parameters in that model;
  3. Identification of measures for each of the key parameters and the development of new measures (such as rating scales) where necessary;
  4. Data sources and data collection;
  5. Statistical analysis; and
  6. Packaging of the final product.

Each of these stages has its own potential rewards and pitfalls that will be illustrated by incidents from the speaker’s own experience. The ultimate goal of the lecture is to provide a new and deeper appreciation for empirical techniques, as well as some guidelines and opportunities for future developers.   

To read biographical sketch, CLICK HERE

Wednesday, 1 July

Friction Mechanics, Onset of Sliding, and Laboratory Earthquakes

Professor Steven D. Glaser, Faculty Director
Center for Information Technology Research in the Interest of Society
Department of Civil and Environmental Engineering
University of California, Berkeley and Distinguished Affiliated Professor, Technical University, Munich, Germany

Improving our understanding of factors controlling spontaneous shear rupture nucleation on a frictional fault would help better define the important physical processes contributing to earthquake rupture and faulting.  Our current laboratory investigations quantify the local stress states on a laboratory fault, which control the transition of sliding from stable (quasi-static) to unstable (dynamic), commonly referred to as rupture nucleation.  A fault is experimentally modeled using two PMMA samples in a direct shear configuration.  A pressure-sensitive film was employed to localize, size, and measure normal stress on contact junctions (asperities) created throughout the interface.  An array of absolutely calibrated piezoelectric acoustic emission sensors are employed to monitor the small (pm), high frequency (~300 kHz), elastodynamic stress waves emitted intermittently prior to unstable dynamic rupture.  Numerical and theoretical modeling of the experimental contact conditions and their related asperity interactions were used to estimate quasi-static slip deficit between the high density patch and its surroundings.

Topics to be discussed include:

To read biographical sketch, CLICK HERE