Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

Carbon dioxide stored underground can find multiple ways to escape
by Staff Writers
University Park PA (SPX) Feb 15, 2016

To recreate natural settings, the researchers conducted an experiment by flowing carbon-dioxide-rich saltwater into two different systems - cement embedded in a sandstone host rock, and cement embedded in limestone. They monitored the chemical reactions that took place and measured changes occurring in the host rocks and cement.

When carbon dioxide is stored underground in a process known as geological sequestration, it can find multiple escape pathways due to chemical reactions between carbon dioxide, water, rocks and cement from abandoned wells, according to Penn State researchers.

The researchers investigated the properties of porous rocks into which carbon dioxide is injected. These rocks, known as host rocks, function like containers for the carbon dioxide. The team looked at two abundant host rocks, limestone and sandstone, which have different chemical properties.

"We were interested in examining these rocks because they are widely found underground, but there have been concerns that carbon dioxide may escape once it's injected underground," said Li Li, associate professor of petroleum and natural gas engineering. "Even if it doesn't escape to the Earth's surface, there are concerns that it may leak into groundwater drinking aquifers."

In addition to encountering host rocks, carbon dioxide stored underground may also contact and dissolve into saltwater deposits. When this happens, the carbon dioxide increases the acidity of the saltwater. The high-acidity saltwater-carbon dioxide mixture can dissolve certain types of rocks, such as limestone, as well as cement casings on abandoned oil and gas wells.

"If this plume of carbon dioxide-saturated brine reaches an abandoned well, it will react with the cement," said Zuleima Karpyn, associate professor of petroleum and natural gas engineering and Quentin E. and Louise L. Wood Faculty Fellow in Petroleum and Natural Gas Engineering. "This may open up cracks in the cement depending on the conditions, which would increase the likelihood of carbon dioxide escaping. We were trying to assess what would happen in the process if the host rock itself were to react with the carbon dioxide-saltwater mixture."

To recreate natural settings, the researchers conducted an experiment by flowing carbon-dioxide-rich saltwater into two different systems - cement embedded in a sandstone host rock, and cement embedded in limestone. They monitored the chemical reactions that took place and measured changes occurring in the host rocks and cement.

Their findings, published in the current issue of the International Journal of Greenhouse Gas Control, indicate that the host rocks can create different types of escape pathways. The saltwater-carbon dioxide solution dissolved parts of the limestone, which lowered the acidity of the solution.

In eight days, the limestone lost 3 percent of its mass and became 24 times more permeable than at the start of the reaction, which means liquids and gases can move through it much easier. The carbon dioxide-saltwater liquid also became less acidic in the dissolution process. As a result, it did not dissolve any of the cement.

"In the limestone interactions, the rock itself becomes the dominant medium for the dissolution reaction while the cement was the secondary reactant," said Karpyn. "This means that wellbores are more likely to stay intact if you have limestone. But dissolving the limestone can create leakage pathways, for example, by forming finger-like channels of dissolved rock."

The researchers found the opposite to be true for the sandstone sample. Rather than dissolving the sandstone, the solution degraded the cement. The sandstone lost very little mass, and the cement lost mass and became more porous.

These findings highlight the complexity of underground carbon sequestration, which is a process under investigation as a method to reduce carbon dioxide levels in the atmosphere.

"The process of assessing whether a site is appropriate for injection has to be system-specific and take into account not only the chemistry and composition of the rocks, but also the ease with which water and carbon dioxide can flow through host rocks," said Li. Peilin Cao, Penn State Ph.D. student, collaborated on this research.

Penn State, the Quentin E. and Louise L. Wood Endowed Faculty Fellowship and the U.S. Department of Energy supported this work.


Related Links
Penn State
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
Plankton carries carbon to safe resting spot
Columbus OH (SPX) Feb 12, 2016
The ocean's power to rein in carbon and protect the environment is vast but not well-understood. But now, an international team of scientists has begun to illuminate how the ocean plucks carbon from the atmosphere, where it contributes to global warming, and shuttles it to the bottom of the sea. The new study establishes the important role of plankton networks in removing carbon from the a ... read more

Edgar Mitchell, astronaut who walked on Moon, dead at 85

The forgotten moon landing that paved the way for today's space adventures

ASU satellite selected for NASA Space Launch System's first flight

Lunar Flashlight selected to fly as secondary payload on Exploration Mission-1

Becoming a Martian

Site of Martian lakes linked to ancient habitable environment

Opportunity climbing steeper slopes to reach science targets

Opportunity Reaches 12 Years on Mars!

Are private launches changing the rocket equation?

NASA tests solar sail deployment for asteroid-surveying CubeSat NEA Scout

Mars or the Moon

The Orion Crew Module Pressure Vessel Ready For Testing

China Conducts Final Tests on Most Powerful Homegrown Rocket

Last Launch for Long March 2F/G

China aims for the Moon with new rockets

China shoots for first landing on far side of the moon

Putting the Public in the Shoes of Space Station Science

Russians spacewalk to retrieve biological samples

Russia to Deliver Three Advanced Spacesuits to ISS in 2016

Russian spacewalk marks end of ESA's exposed space chemistry

Arianespace to launch two ViaSat high capacity satellites

SpaceX Conducts Hover Tests

Space Launch System's first flight will launch small Sci-Tech cubesats

Initial launcher assembly clears Ariane 5 for its payload integration process

Earth-like planets have Earth-like interiors

The frigid Flying Saucer

Astronomers discover largest solar system

Lonely Planet Finds a Mum a Trillion Km Away

Scientists from MIPT gain insights into 'forbidden' chemistry

Some 5,000 years ago, silver mining on the shores of the Aegean Sea

Flow phenomena on solid surfaces

Twisted X-rays unravel the complexity of helical structures

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.