 |
|
Increased flow of groundwater after earthquakes suggests oil extraction applications
June 29, 2006SANTA CRUZ, CA—The most obvious manifestation of an earthquake is the shaking from seismic waves that knocks down buildings and rattles people. Now researchers have established a more subtle effect of this shaking—it increases the permeability of rock to groundwater and other fluids.
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.
University of California—Santa Cruz
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.
University of California—Santa Cruz
Earthquake, Current Events and Earthquake, News RSSA new approach in tsunami-early warning
The newly implemented Tsunami Early Warning System for the Indian Ocean, GITEWS, goes into operation today and with this, the system enters its final phase of optimisation.
Conclusive vote on cause of Indonesian mud volcano
A resounding vote of international petroleum geologists from around the globe concluded that the mud volcano was triggered by drilling of a nearby gas exploration well.
May 2008 earthquake in China could be followed by another significant rupture
Researchers analyzing the May 2008 Wenchuan earthquake in China's Sichuan province have found that geological stress has significantly increased on three major fault systems in the region.
Major flooding risk could span decades after Chinese earthquake
Up to 20 million people, thousands of whom are already displaced from their homes following the devastating Chinese earthquake, are at increased risk from flooding and major power shortages in the massive Sichuan Basin over the next few decades and possibly centuries.
New NIST publication series addresses design of earthquake-resistant structures
Where can you find some of the latest insights in designing earthquake-resistant buildings joined together with current information on building codes?
Magmatically triggered slow earthquake discovered at Kilauea Volcano, Hawaii
Kilauea experienced a new dike intrusion, where magma rapidly moved from a storage reservoir beneath the summit into the east rift zone and extended the rift zone by as much as 1 meter.
Earthquakes may endanger New York more than thought, says study
A study by a group of prominent seismologists suggests that a pattern of subtle but active faults makes the risk of earthquakes to the New York City area substantially greater than formerly believed.
Durham scientist explores Sichuan fault
Durham University expert, Alex Densmore, is to explore the fault lines that caused the May 12th earthquake in China that killed 69,000 people.
Chinese earthquake provides lessons for future
The May 12 Sichuan earthquake in China was unexpectedly large. Analysis of the area, however, now shows that topographic characteristics of the highly mountainous area identified the mountain range as active and could have pointed to the earthquake hazard. Topographic analysis can help evaluate other, similar fault areas for seismic risk, according to geologists from Penn State and Arizona State University.
A stress meter for fault zones
For the first time, scientists from Rice University, the Carnegie Institution of Washington, and the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have measured - in the field rather than in the laboratory - how changes in stress in rocks affect changes in the speed of seismic waves at depths where earthquakes begin.
More Earthquake, Current Events and Earthquake, News Articles
 | Little Earthquakes : A Novel (Washington Square Press) by Jennifer Weiner This is the story of what comes after 'happily ever after' as three young wives make the journey into motherhood, and discover how it changes their sense of themselves and their relationships with friends and family. There's Becky, a plump, sexy chef, with an overworked husband, an adorable baby girl ...and the mother-in-law from hell. There's Kelly, an event planner who's trying to cram sixty... |
| The Coming Economic Earthquake by Larry Burkett | |
 | Earthquake in the Early Morning (Magic Tree House #24) (A Stepping Stone Book(TM)) by Mary Pope Osborne Jack and Annie travel back to the morning of the great San Francisco earthquake. While they are there, they meet a reporter and help get some kids to... |
 | The Coming Economic Earthquake: Revised and Expanded for the Clinton Agenda by Larry Burkett This edition of Burkett's bestseller has been expanded to include the Clinton agenda, and discusses the President's new budget package, the NAFTA proposal, and the national health care issue. Burkett is the bestselling author of The Complete Financial Guide for... |
 | Volcano & Earthquake (DK Eyewitness Books) by Susanna van Rose The most trusted nonfiction series on the market, Eyewitness Books provide an in-depth, comprehensive look at their subjects with a unique integration of words and pictures. DK's classic look at volcanoes and earthquakes, now reissued with a CD and wall... |
 | Apocalypse: Earthquakes, Archaeology, and the Wrath of God by Amos Nur, Dawn Burgess What if Troy was not destroyed in the epic battle immortalized by Homer? What if many legendary cities of the ancient world did not meet their ends through war and conquest as archaeologists and historians believe, but in fact were laid waste by a force of nature so catastrophic that religions and legends describe it as the wrath of god? Apocalypse brings the latest scientific evidence to bear on... |
| The Coming Economic Earthquake by Larry Burkett | |
 | Fundamentals of Earthquake Engineering by Amr Elnashai, Luigi Di Sarno Fundamentals of Earthquake Engineering combines aspects of engineering seismology, structural and geotechnical earthquake engineering to assemble the vital components required for a deep understanding of response of structures to earthquake ground motion, from the seismic source to the evaluation of actions and deformation required for design. The nature of earthquake risk assessment... |
 | Earthquake Terror (Puffin Novel) by Peg Kehret When Jonathan and his family go camping on Magpie Island, they look forward to a fun, relaxing weekend. But their fun quickly vanishes when Jonathan, his sister, Abby, and their dog, Moose, find themselves in the middle of a natural disaster. A devastating earthquake has hit, destroying their camper, knocking out the only bridge to the mainland, and leaving Jonathan, Abby, and their dog ... |
 | If You Lived At The Time Of The Great San Francisco Earthquake (If You.) by Ellen Levine This book takes you to San Francisco, California, shortly before, during, and after April 18, 1906. What would you have done when the quake... |
| © 2008 BrightSurf.com |