The enhanced permeability caused by seismic shaking could potentially be harnessed to help extract oil from natural reservoirs, said Emily Brodsky, assistant professor of Earth sciences at the University of California, Santa Cruz.
"Permeability governs how fluid flows through rocks, whether it's water or oil, so this has practical implications for oil extraction," Brodsky said.
Brodsky is coauthor of a paper describing the new findings in the June 29 issue of Nature. The first author is Jean Elkhoury, a graduate student who worked with Brodsky at UCLA, and the other coauthor is Duncan Agnew of UC San Diego.
The study was based on two decades of data from the Piñon Flat Observatory in southern California, where researchers from UCSD's Scripps Institution of Oceanography maintain an extensive geophysical observatory.
"It's probably one of the best-monitored pieces of land anywhere on Earth," Brodsky said.
The monitoring includes records of fluctuating water levels in wells. The water levels fluctuate in response to tidal effects similar to oceanic tides. In this case, the gravitational effects of the moon on the solid Earth squeeze and stretch the rocks in the crust, forcing water in and out of the wells from the surrounding rocks. The speed of the response in a well depends on the permeability of the surrounding rock.
"We know the tidal strain very well, so we can measure the lag between the imposed tidal strain and the response in the well to get a precise measure of the permeability of the rock," Brodsky said.
The researchers analyzed the data in relation to earthquakes and saw a striking correlation. "Every time there's a big earthquake in southern California, the permeability jumps. We saw this in two different wells for more than seven different earthquakes," Brodsky said.
After an earthquake, the rock surrounding the wells became as much as three times more permeable to groundwater, she said. Furthermore, the size of the increase in permeability was proportional to the peak amplitude of the shaking. The changes were transient, with permeability returning to the original level within a few months after an earthquake.
The oil industry might be able to exploit this phenomenon by using "vibroseis" trucks to send seismic waves into the ground. Currently used for seismic imaging studies, vibroseis trucks vibrate at a particular frequency for a prolonged period.
"If we understood the physics of the permeability enhancement well enough, the vibrations could be tuned to increase the flow of oil," Brodsky said.
Tim Stephens | EurekAlert!
Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute
Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine