Depleted gas reservoirs can double as geologic carbon storage sites

Jan 06, 2012 by Dan Krotz
Aerial view of the Otway Project in Australia (Image: CO2CRC).

(PhysOrg.com) -- A demonstration project on the southeastern tip of Australia has helped to verify that depleted natural gas reservoirs can be repurposed for geologic carbon sequestration, which is a climate change mitigation strategy that involves pumping CO2 deep underground for permanent storage.

The project, which includes scientists from Lawrence Berkeley National Laboratory (Berkeley Lab), also demonstrated that depleted gas fields have enough capacity to make a significant contribution to reducing .

During an 18-month span beginning in April 2008, an international team of researchers injected 65,000 tonnes of CO2-rich gas two kilometers underground into a depleted gas field in western Victoria, Australia. That’s about 130 tonnes of CO2 per day, or the amount emitted by a small, 10-megawatt power plant. It’s also the daily CO2 emissions required to supply 6000 average U.S. homes with electricity.

Extensive monitoring conducted during and after the injection found no measureable effect of stored CO2 on soil, groundwater, or the atmosphere.

“There was no discernible leakage. The CO2 stayed within the reservoir and behaved as expected,” says Barry Freifeld, a mechanical engineer in Berkeley Lab’s Earth Sciences Division who helped set up and interpret the site’s well-based monitoring equipment.

Geological cross-section of the Otway Project. CO2-rich gas is extracted from the Buttress well (on the left), injected into the depleted gas field using CRC-1, and the Naylor-1 well houses the monitoring equipment installed by Berkeley Lab scientists. Faults are black lines.

The Otway Project is run by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), an Australian-led collaboration of universities and research organizations that includes Berkeley Lab scientists. The science behind the project is outlined in a paper published online last month in the journal Proceedings of the National Academy of Sciences.

Geologic carbon sequestration involves capturing CO2 from large stationary sources, such as coal-burning power plants, and injecting it deep underground into rock formations that trap the greenhouse gas. The technology holds promise as a way to curb climate change because fossil fuels will likely remain cheap and plentiful for decades to come.

Scientists are looking to depleted gas reservoirs as a possible target for because the reservoirs have a proven ability to store gas. The same caprock that trapped natural gas for millions of years can also trap CO2. Depleted gas reservoirs also provide some of the infrastructure needed for injection, such as boreholes and a pipeline network.

Berkeley Lab engineer Barry Freifeld (left) and Otway Project Program Manager Sandeep Sharma complete the Naylor-1 wellhead installation after a two-week long workover operation to install Berkeley Lab's monitoring instruments.

They’re also plentiful. A 2009 report by the International Energy Agency Greenhouse Gas R&D Program estimates that 160 gigatons of capacity in depleted gas fields—matched to point sources—will be available by 2050.

But the science of storing CO2 in depleted gas fields has needed real-world verification, which is why the CO2CRC team started the Otway Project. The group developed computer models to track the subsurface flow of CO2 at the site. They conducted risk assessment analyses and met with members of the surrounding community. They also blanketed the site with a network of soil, groundwater, air, and subsurface monitoring equipment.

As part of this effort, Freifeld and fellow Berkeley Lab scientist Tom Daley traveled to Otway in 2007, before CO2 injection began, to help oversee the installation of fluid sampling tools called U-tube samplers. The apparatus was developed at Berkeley Lab and enables the collection of subsurface fluids at the same pressures that occur deep underground, preserving the samples’ chemical integrity during the collection process.

Three U-tube samplers were lowered deep into a borehole that was once used to extract natural gas, but is now used for monitoring purposes only. Once the operation began in 2008, technicians collected U-tube samples almost weekly. These samples allowed scientists to monitor the CO2 as it filled the reservoir.

U-tube sampling: High quality well bore fluid and gas samples are collected at reservoir pressure from multiple levels to detect the CO2 arrival at the Naylor-1 well and to characterize chemical changes associated with the CO2 arrival. (Image: CO2CRC)

Freifeld and Daley also installed extremely sensitive seismic and acoustic monitoring equipment in the borehole that enabled technicians to ”image” the movement of CO2 within the reservoir.

“We found what we expected. The CO2 largely replaced the volume previously occupied by the natural gas,” says Freifeld. “The reservoir had filled with water since the natural gas was extracted, and we watched as the injected CO2 pushed the water to a level below our instruments.”

Additional calculations conducted by the CO2CRC team predict that between 56 percent and 84 percent of the space originally occupied by the is now reoccupied by CO2. These findings help buttress the conclusion that depleted gas fields have enough to make a significant contribution to reducing global emissions, the authors say in their Proceedings of the National Academy of Sciences paper.

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More information: The paper, “Safe storage and effective monitoring of CO2 in depleted gas fields,” was published the week of Dec. 12 in the online early edition of the Proceedings of the National Academy of Sciences.

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User comments : 14

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tadchem
4 / 5 (4) Jan 06, 2012
The Cliffside Gas Field in Potter County, TX has been used to contain suplies of helium since 1925. Tha National Helium Reserve currently contains over 1 billion cubic meters of gas. If helium won't leak from a depleted gas reservoir, CO2 certainly won't.
The only caveat is that at sufficient pressure CO2 liquifies, leading to the same seismic consequences as fracking.
MR166
1.9 / 5 (9) Jan 06, 2012
Using government or educational monies for useless projects like this is part of the reason that tuition is so high and people are unable to pay back their student loans. Everybody knows that sacrificing virgins is the time honored way of preventing climate change and that it has kept man safe from nature's wrath for centuries. It is also very cost effective.
rubberman
2.6 / 5 (5) Jan 06, 2012
Using government or educational monies for useless projects like this is part of the reason that tuition is so high and people are unable to pay back their student loans. Everybody knows that sacrificing virgins is the time honored way of preventing climate change and that it has kept man safe from nature's wrath for centuries. It is also very cost effective.


So I guess the MR in your handle stands for mentally retarded.

rubberman
2.7 / 5 (7) Jan 06, 2012
This is good news. In the event the rest of the worlds high CO2 emitters realize they'll have to start doing something to curb emissions, knowing there is a proven solution for a place to start sequestering can only help.
MR166
2 / 5 (8) Jan 06, 2012
Rubberman if you believe any of this big/one world government sponsored AGW crap you deserve the slavery they will impose upon you and your children. Just don't expect me to give up my hard earned liberties to support this unproven farce.
rubberman
3 / 5 (8) Jan 06, 2012
I believe in raw data, good science and human nature. The last one contradicts the first two.

I workrd equally hard to obtain my "liberties" and i was raised in a culture that thinks it's people are all free to pursue the same thing. They are wrong. The resources I have consumed in my pursuit will for the most part be unavailable in 50-100 years time. Climate change is real and it is very unsettling that the rate is actually observable in a human lifetime. Scarier still if you follow ALL of the fringe factors surrounding the change. Even if it is natural, it isn't exempt from man made feedbacks. As long as there are borders there will never be a one world government and the slavery you fear won't be politically imposed. We are all slaves to the world we've created, as the world changes so does the nature of the slavery. China is a perfect example, they westernized their lifestyle...fast. Now they have 40 cities of over a million people who need filters to breathe 1/2 the time.
MR166
2.1 / 5 (11) Jan 06, 2012
"I believe in raw data, good science and......."

I believe in "raw data" also, funny how they refuse to release it. The data is not raw any longer. It has been cooked, molded into hockey sticks and fed to the gullible.
Xbw
1.5 / 5 (6) Jan 06, 2012
Back on topic here. Would it be possible to physically "dump" the emissions from coal burning plants through a pipeline to the nearest empty natural gas well? Or would it have to be physically transported by vehicles? The ladder would seem to negate the positive effects.
MR166
1.9 / 5 (9) Jan 06, 2012
Back on the REAL topic, why would you want to spent billions of dollars to sequester a trace gas by 3% ( the man made component of CO2 emissions )!
MarkyMark
4 / 5 (4) Jan 07, 2012
Back on the REAL topic, why would you want to spent billions of dollars to sequester a trace gas by 3% ( the man made component of CO2 emissions )!

Its when people like you de-rail interesting topics like this with off topic BS that proves that deniall is not just a river.
Sherrin
not rated yet Jan 07, 2012
"A demonstration project on the southeastern tip of Australia ..." Why describe the project location in this manner? The Otway Ranges are in southern Victoria (38 deg, 51' S). The 'southeastern tip' of Australia is actually Cape Pillar in Tasmania (43 deg 13' S). The article description makes it sound like the project is being conducted as far away as possible (i.e. the project might somehow be unsafe to all Northern Hemispherians). What gives? Cape Otway is not too far from the Melbourne-Geelong metropolis (4m pop).
Wolf358
1 / 5 (1) Jan 07, 2012
It's high-stakes gambling. Put toxic waste gasses under ground, under pressure, and bet that you'll make your winnings and get out of the casino before a pressure vessel made out of fractured rock cracks open, leaks, and kills a few thousand or more people... sure. As long as the victims pay for it all, why not?
Shootist
1.5 / 5 (6) Jan 07, 2012
It's high-stakes gambling. Put toxic waste gasses under ground, under pressure, and bet that you'll make your winnings and get out of the casino before a pressure vessel made out of fractured rock cracks open, leaks, and kills a few thousand or more people... sure. As long as the victims pay for it all, why not?


Funny how all that noxious stuff was in the ground to begin with, and didn't "fracture (the) rock crack open, leaks amd kills yada yada".
rubberman
1 / 5 (1) Jan 09, 2012
Back on topic here. Would it be possible to physically "dump" the emissions from coal burning plants through a pipeline to the nearest empty natural gas well? Or would it have to be physically transported by vehicles? The ladder would seem to negate the positive effects.


It (the pipeline) would be possible but you would be creating the most expensive exhaust port ever made, unless the well was conveniently located very close to the power plant.

@ Shootist- you know the difference between solids and vapours...right?