Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Shakedown in Oklahoma: To cut the number of bigger earthquakes, inject less saltwater

05.01.2018

In Oklahoma, reducing the amount of saltwater (highly brackish water produced during oil and gas recovery) pumped into the ground seems to be decreasing the number of small fluid-triggered earthquakes. But a new study shows why it wasn't enough to ease bigger earthquakes. The study, led by Ryan M. Pollyea of Virginia Tech in Blacksburg, Virginia, was published online ahead of print in Geology this week.

Starting around 2009, saltwater disposal (SWD) volume began increasing dramatically as unconventional oil and gas production increased rapidly throughout Oklahoma. As a result, the number of magnitude 3-plus earthquakes rattling the state has jumped from about one per year before 2011 to more than 900 in 2015. "Fluids are basically lubricating existing faults," Pollyea explains. Oklahoma is now the most seismically active state in the lower 48 United States.


Figure 2 from Pollyea et al., Annual geographic centroid locations for the years 2011-2016 (the underlying fault map is by Marsh and Holland, 2016), including volume-weighted well centroids, the 1σ radius of gyration, and M3+ earthquake centroids.

Credit: Pollyea et al. and Geology

Previous studies linked Oklahoma SWD wells and seismic activity in time. Instead, Pollyea and colleagues studied that correlation in space, analyzing earthquake epicenters and SWD well locations. The team focused on the Arbuckle Group, a porous geologic formation in north-central Oklahoma used extensively for saltwater disposal. The earthquakes originate in the basement rock directly below the Arbuckle, at a depth of 4 to 8 kilometers.

The correlation was clear: "When we plotted the average annual well locations and earthquake epicenters, they moved together in space," says Pollyea. The researchers also found that SWD volume and earthquake occurrence are spatially correlated up to 125 km. That's the distance within which there seems to be a connection between injection volume, fluid movement, and earthquake occurrence.

By separating data by year from 2011 through 2016, Pollyea and colleagues also found that the spatial correlation for smaller earthquakes weakened in 2016, when new regulations reduced pumping volumes. Yet the spatial correlation for M3.0+ earthquakes persists unabated. In fact, two particularly alarming earthquakes shook the region in September 2016 and November 2016. The first, M5.8, was the largest ever recorded in Oklahoma. The second, M5.0, rocked the area surrounding the nation's largest oil storage facility, containing millions of barrels of oil.

Pollyea's theory for why reduced fluid pressure has only affected small faults: "It's like the traffic on the freeway is still moving, but the smaller arterials are cut off." He emphasizes that so far, they can't predict single earthquakes or even blame specific wells for specific shaking. But to reduce large fluid-triggered earthquakes, Pollyea concludes, "It appears that the way to do it is to inject less water."

Image: Figure 2 from Pollyea et al., Annual geographic centroid locations for the years 2011-2016 (the underlying fault map is by Marsh and Holland, 2016), including volume-weighted well centroids, the 1σ radius of gyration, and M3+ earthquake centroids.

###

FEATURED ARTICLE

Geospatial analysis of Oklahoma (USA) earthquakes (2011-2016): Quantifying the limits of regional-scale earthquake mitigation measures Authors: Ryan M. Pollyea (Virginia Tech; rpollyea@vt.edu); Neda Mohammadi; John E. Taylor; Martin C. Chapman; https://pubs.geoscienceworld.org/gsa/geology/article/525806/geospatial-analysis-of-oklahoma-usa-earthquakes.

GEOLOGY articles are online http://geology.geoscienceworld.org/content/early/recent. Representatives of the media may obtain complimentary articles by contacting Kea Giles at the e-mail address above. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GEOLOGY in articles published. Non-media requests for articles may be directed to GSA Sales and Service, gsaservice@geosociety.org.

http://www.geosociety.org/

Kea Giles | idw - Informationsdienst Wissenschaft
Further information:
http://www.geosociety.org/GSA/News/pr/2018/18-01.aspx

More articles from Earth Sciences:

nachricht Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen

nachricht The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Controlling organ growth with light

19.11.2018 | Life Sciences

New way to look at cell membranes could change the way we study disease

19.11.2018 | Life Sciences

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

VideoLinks
Science & Research
Overview of more VideoLinks >>>