DOE Physicists at Work
Profiles of representative DOE-sponsored physicists
doing research at universities and national laboratories
Compiled by the Office of Scientific and Technical Information
Beware of going on a hike with Laura Pyrak-Nolte, professor in the Department of Physics at Purdue University. "I'm known for convincing my friends to carry boulders miles back to the car," says Dr. Pyrak-Nolte. A student once asked if that was because Pyrak-Nolte wanted to understand the geologic forces that created such a rock. "I said, no, I just liked the way it looked."
That peculiar interest in looking at as well as into rocks has been a steady theme throughout her career. Her particular interest became fractures in rock, a research topic she was introduced to as a graduate student at the University of California, Berkeley, when she took a graduate course with Prof. Neville G. W. Cook on fracture mechanics. In just one semester, what was intended to be a short individual project on fracture stress field interactions expanded into an exhaustive exploration of interaction space, with a report as thick as a thesis. Shortly thereafter she received an invitation to work in his group. Though her background had been in computational geophysics, Prof. Cook asked whether she would mind doing laboratory experiments for her thesis. "I agreed, and it was perhaps the best decision I ever made in my life," says Dr. Pyrak-Nolte. Dr. Cook awakened in me a latent talent for performing experiments and a love of working in the laboratory."
This became her forte, as she pursued experimental work illuminating the fundamental physics of how fluid transport and seismic activity are related in fractured materials, such as rock. Her work has focused on detecting fractures in rock and determining their ability to support fluid flow.
From extracting oil and gas, to remediating contaminated groundwater or sequestering carbon dioxide or nuclear waste, fractures are the major conduits that transport fluids in the Earth's subsurface. Dr. Pyrak-Nolte envisions a time when the flow properties of fractures deep inside rock can be characterized seismically. "This is no idle dream," she says. "I have been steadily assembling the experimental evidence and theories that demonstrate the connection between fluid flow in fractures and their seismic signatures." During her graduate studies, Dr. Pyrak-Nolte demonstrated from laboratory experiments that a wide range of disparate phenomena were unified under a simple theory for wave transmission across fractures. As an assistant professor at the University of Notre Dame, she received Young Investigator awards from the National Science Foundation and the Office of Naval Research, as well as the Schlumberger Award of the International Society of Rock Mechanics. There she imaged and quantified natural fracture networks in coal as well as determined how to use seismic interface waves to detect fracture formation. Now, at Purdue, she and her students are examining reactive and depositional flows in which the fluids either erode the fracture, or deposit minerals in the fractures, thus altering their flow properties as well as their ability to transmit seismic energy.
In one of her last visits with Dr. Cook, he reminded her that no matter the volume of rock under consideration, mechanical discontinuities, such as fractures, cracks and pores, will be present.
"This now forms the theme of my current research," says Dr. Pyrak-Nolte, noting that she is interested in the effect of physical length scales associated with fluid flow, chemical reactions, stress, and seismic wave propagation on seismic monitoring of fractures.
Dr. Pyrak-Nolte's articles accessed via OSTI:
Experimental Investigation of Relative Permeability Upscaling from the Micro-Scale to the Macro-Scale