Geotimes
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Energy & Resources
Burying carbon dioxide, Part II
Cuban oil find
Mineral of the Month: Tin


Burying carbon dioxide, Part II

By the 1960s, oil production at the Weyburn oil field, a giant field in Saskatchewan, Canada, had reached its peak. Thirty years later, EnCana Corporation, the energy company that was producing oil at the field, decided to inject carbon dioxide into some of the more than 1,000 wells at the site to try to enhance oil recovery. Since then, the company has injected more than 2 billion cubic meters of carbon dioxide into the field, and a broad consortium of scientists has been studying what happens to the gas once it is belowground.

Energy companies in the United States, Canada and elsewhere have been using carbon dioxide for enhanced oil recovery, or EOR, for at least 25 years to stimulate oil production at wells. But some geoscientists have been interested in another benefit of EOR: capturing carbon dioxide before it enters the atmosphere and “completing the cycle” by putting the carbon “back underground where it belongs,” says Susan Hovorka, a researcher at the Bureau of Economic Geology at the University of Texas in Austin. “Storage of carbon dioxide in [oil] reservoirs can be a significant help to reducing carbon emissions,” says Hovorka, who is involved in a carbon sequestration project in Texas (see part I of this story, Geotimes, February 2005).

Researchers are exploring other methods of carbon sequestration around the world, including injecting carbon into geologic saline formations or ocean sediments (see Geotimes, March 2003), and the U.S. Department of Energy (DOE) has made carbon sequestration technologies one of its primary research and development goals. Storage in conjunction with EOR is especially appealing, however, because the increased oil production provides economic incentive, and because oil reservoirs are some of the best-studied geological formations.

Today, EnCana pumps an average of 2.8 million cubic meters of carbon dioxide per day into the wells at Weyburn. The carbon dioxide is pumped in via a 320-kilometer pipeline from the Dakota Gasification Company’s synthetic fuel plant in Beulah, N.D.

As EnCana pumps carbon dioxide into the subsurface, Ben Rostron, a geologist at the University of Alberta, and colleagues have been watching the movement of the gas through seismic profiles and have tested the subsurface water and oil to check for any geochemical changes, Rostron says — very similar to what Hovorka and colleagues did in Texas. The researchers have also been monitoring to check for any gas leakages at the surface. A slow leak of gas would cancel out any benefits of injection. At the Weyburn field, as predicted, the reservoir’s natural confining layers have trapped the carbon dioxide, preventing any leakage. The same trapping process has occurred in EOR carbon sequestration projects in Texas, Wyoming and Norway as well.

“The results were very encouraging in terms of performance of the reservoir in containing the carbon dioxide, the performance of the monitoring technology and the response of the reservoir to the carbon dioxide for enhanced oil recovery,” says Michael Monea, executive director of the Petroleum Technology Research Centre in Regina, Saskatchewan, which coordinated the researchers involved in the project. And as for increasing oil production, EOR “works like a charm,” Rostron says. The production rates have “gone way up” at Weyburn, he says.

Still, Monea adds, “as with any project of this magnitude, the science reveals further areas to explore and areas that need improvement.” In the coming months, the researchers will use their “lessons learned” to improve models of reservoirs, and to develop new and less expensive ways to implement technologies that have proved successful over the past five years.

The researchers, from the International Energy Agency, DOE, Natural Resources Canada, and other European and Canadian organizations, as well as from several universities and industry, have integrated the diverse research and compiled the results — some of which were published in last July’s GSA Today. Now, Rostron says, it’s just a matter of convincing the public that this is a process ready to go forward, and convincing the oil and gas companies that it’s worth their investment.

“The oil companies’ investment in the technology will essentially be weighed on a cost-recovery basis,” Monea says, “meaning that the companies will be looking for some form of compensation,” such as carbon credits, “or looking to avoid paying carbon production penalties.”

Having successful projects such as the Weyburn project, a similar project in Norway that’s been ongoing since 1996 (see Geotimes, December 2004), and the successful tests in Texas and elsewhere, will make companies more likely to be interested, Rostron says. “I do think that oil and gas companies will be ‘jumping on board’” to use EOR to breathe new life into older fields, Monea says.

With the growing output of carbon dioxide emissions worldwide and the Kyoto protocol going into effect in February, there’s going to be a growing need to put the carbon dioxide somewhere, Rostron says. “In 10 years, it is my hope that carbon dioxide storage is becoming routine,” Monea says.

Megan Sever

Read last month's “Burying carbon dioxide, Part I.”

Links:

"U.S. Offshore Oil Industry: New perspectives on an old conflict," Geotimes, December 2004
Geotimes, March 2003


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Cuban oil find

Two Canadian oil companies, Pebercan and Sherritt International, discovered a new oil field in Cuban waters in the Gulf of Mexico. Although the companies have not announced the extent of the finds, Cuban President Fidel Castro, in a Dec. 25 announcement, claimed the reserves to be on the order of 100 million barrels.

Cuba has produced its own oil since the late 1800s. The country, however, which used to import oil from the Soviet Union before its collapse in 1991, now imports at least 53,000 barrels of oil per day from Venezuela, according to the U.S. Department of Energy. With Cuba consuming anywhere from 150,000 to 210,000 barrels of oil per day for electricity, transportation fuel and other uses, it is still in need of petroleum, says Omayra Bermúdez-Lugo, a country specialist with the U.S. Geological Survey (USGS).

The newly discovered offshore oil is reported to be of higher quality and lighter grade than the oil in onshore reserves on Cuba, says Chris Schenk, a petroleum geologist at USGS. But while the new discovery sounds big, he says, “it probably won’t alleviate Cuba’s needs.”

Because Canada, unlike the United States, does not have a trade embargo with Cuba, the Canadian companies will most likely sell all of the oil to the Cuban government. The deposits “will probably be used domestically, every drop of it,” Schenk says.

Laura Stafford

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Mineral of the Month: Tin

James F. Carlin Jr., the tin commodity specialist for the U.S. Geological Survey, has compiled the following information on tin, an important industrial metal.

Tin was one of the first metals discovered by humans and, like most metals, tin is rarely used by itself. Most tin is used as a protective coating or as an alloy with other metals in a diverse range of commercial and defense applications.

During the past century, tinplate was the dominant consumption category for tin. A thin, flat-rolled steel industry product, tinplate has a coating of tin on both sides and is used to make tin cans. In the early 1960s, however, tinplate consumption declined substantially, with the introduction of the aluminum can, coupled with the fact that the canning industry found that it could use thinner tin coatings and still achieve desired corrosion resistance.

Now, solder, an alloy of approximately 70 percent tin and 30 percent lead, is the dominant tin product. Significant amounts of solder are used in the construction and transportation industries, but the major use is in electronics, where it finds applications in virtually all modern high technology, ranging from computers to microwave ovens. As government regulation has reduced the presence of lead in society, tin has gained market share in the solder consumption sector, in new low-lead or no-lead solders.

The chemical industry is the second largest U.S. tin user. Tin chemicals are present in wood preservatives, stabilizers for making polyvinyl chlorides (PVC), and fungicides and biocides. Inorganic tin chemicals are used as reducing agents in the manufacture of perfume and soap stabilizers, and in the production of polyurethane.

Other important uses include tinning (mostly hot-dip coating of tin onto copper wire used in underground utility cables); brass/bronze (often used for electrical contacts and naval gear); pewter (often used for decorative items); and dental amalgams.

Tin is a relatively scarce element in Earth’s crust. Principal deposits are scattered irregularly around the Pacific Rim, and about one-half of global supply comes from south Asia.

U.S. primary tin consumption was estimated to be about 33,000 metric tons in 2003, while tin imports to the United States were about 37,000 metric tons. Tin has long been one of the major components of the National Defense Stockpile, and disposals from the stockpile have taken place regularly since 1960, providing an important contribution to domestic tin supply. Although the United States has limited tin resources, scrap or recycled tin has been an important segment of domestic tin supply, accounting for about 20 percent of all tin used domestically.

In 2003, world tin mine production totaled 209,000 metric tons. Tin was mined in 20 countries, but the top 6 accounted for 93 percent of the world total, with Indonesia as the leading producer. World tin reserves were estimated to be 8 million metric tons. Assuming a world primary tin consumption of about 200,000 metric tons per year, these reserves would last 40 years at current rates of consumption.

For more information on tin, visit minerals.usgs.gov/minerals.

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