Easing oil’s flow

Researchers have figured out a new way to make crude oil flow faster using electric and magnetic pulses. They hope such technologies will help harvest crude oil buried in fields deep below the seafloor.

Cold temperatures can make it nearly impossible for thick asphalt-based crude oil to flow through a pipeline, such as the TransCanada Mainline in western Canada. New research suggests electric pulses could ease the oil flow. Photograph is copyright TransCanada Pipelines Limited.

Low temperatures in offshore pipelines decrease oil’s ability to flow, so that it is much more difficult to move through the pipelines. But the seemingly simplest solution — heating those pipelines — has proven difficult and expensive, says Rongjia Tao, a physicist at Temple University in Philadelphia, Pa.

While some companies still use heat, perhaps the most common way energy companies currently reduce oil viscosity is through the use of chemical additives, which modify the internal structure of the oil and allow it to flow more easily, says Ken Barker, a chemist with Baker Petrolite in St. Louis. Companies, however, are always trying new options to improve the efficiency of the process.

In China and Russia, for example, companies frequently dilute the crude oil with gasoline, Tao says. And the Department of Energy has looked at adding bacteria or other biological agents to improve flow rates. People also have tried using magnets since at least the 1970s, Barker says, but until now, such experiments have lacked a solid foundation.

The new method, described by Tao and colleague Xiaojun Xu in the Sept. 20 Energy & Fuels is based on a simple concept, Tao says: Send a magnetic or electric pulse through the pipeline and into the oil. That pulse causes the wax-like molecules in the crude oil to cluster together into a smaller number of large particles, which makes it flow more easily. The trick, he says, is not to overdo it or you can have the opposite effect; too much clumping will increase the viscosity of the oil.

So Tao and Xu ran a series of experiments to see exactly what level of pulses was needed to maximize the flow rate of both paraffin-based oil and asphalt-based oil. Paraffin-based crude is common in Asia and the Middle East, and asphalt-based oil is most common in North America.

They found that 1- to 3-second-long magnetic pulses were best for increasing the flow rate of paraffin oil, while seconds-long electric pulses worked best on asphalt-based oil. The pulses could keep the oil flowing easily for up to 12 hours. Once the oil started to thicken again, the pulses could be reapplied to thin the oil for another few hours, Tao says. In a pipeline, the magnetic or electric pulse machines could be separated several kilometers apart to apply the pulses as soon as the oil viscosity starts to increase, he says.

Barker says that it is probably accurate that applying a pulse will affect the oil’s viscosity, but to what degree, he does not know. “This research is good and offers an explanation for why these [electric and magnetic] fields will work, but how significant it will be remains to be seen,” he says. Every crude oil has slightly different properties, he says, and Tao and Xu only looked at several samples, so more research is necessary.

Tao agrees that they need to further experiment with flow rates in the field and with different types of oil, including heavy oil and oil sands. But meanwhile, he and Xu have sought a patent on their technology, and a California company is planning to develop it.

Megan Sever

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Did you know?: Gas theft cost the convenience store industry $300 million in 2005.

That number comes from the National Association of Convenience Stores (NACS). And although gasoline prices have fallen significantly this fall — from a national average of $3.04 per gallon of regular gas on Aug. 7 to $2.31 per gallon by Oct. 2, according to the U.S. Energy Information Administration (EIA) — thefts of gasoline are still on the rise.

Gasoline price volatility throughout 2005, especially with the spike following Hurricane Katrina in August 2005, led to a 27 percent increase in gas thefts over 2004, according to NACS. And the problem would have been far worse if many retailers had not begun to mandate that customers pre-pay following Katrina.

Besides being illegal, gasoline theft hurts honest consumers, NACS says, in that retailers often have to charge more to make up for the lost gas, as they make so little profit off each gallon. In fact, for each $60 of gas stolen, a retailer would have to sell an extra 3,000 gallons of gas to recoup the loss. NACS says the increase in thefts is directly related to price increases, rather than simply high prices.

States are fighting back, by raising the fines and jail time for gas thefts: In Virginia, for example, gas theft is punishable by up to a year in jail and/or a $2,500 fine. Gas stations are fighting back too, NACS says, by installing high-tech surveillance cameras, or simply mandating that customers pre-pay.

Gas prices have recently fallen due to falling crude oil prices, decreased demand, increased supplies, the change-over from summer to winter blends of gas that are cheaper to produce, and this year’s weaker hurricane season. Prices are expected to stay fairly low through January, before rising again going into next summer, according to EIA.

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7-Eleven and Citgo part ways

After a 20-year partnership, 7-Eleven and Citgo, a Houston-based subsidiary of Venezuela’s state-run oil company PDVSA, will go their separate ways. The separation is part of a phase-out plan that was designed to allow 7-Eleven to launch its own brand of fuel or buy gasoline from the cheapest supplier starting last month. Some people have suggested, however, that 7-Eleven has been trying to distance itself from Citgo — and thus Venezuela’s president, Hugo Chavez, who in a Sept. 20 speech at the United Nations called U.S. President Bush “the devil.”

The phase-out plan has been in place for almost a year, according to 7-Eleven’s spokesperson, Margaret Chabris, but “Chavez’s position and statements over the past year or so didn’t tempt us to stay with Citgo,” as reported by The Houston Chronicle on Sept. 28. Still, Chabris said, the separation was simply business, and not a political commentary.

Chavez’s remarks have stirred up some Americans, however, who have been calling for a boycott of Citgo.

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M. Michael Miller, the barite commodity specialist for the U.S. Geological Survey, has prepared the following information on barite, which plays an important role in the exploration for oil and gas.

Also called barytes, barite forms in various geologic environments and is frequently found with both metallic and nonmetallic minerals. Most barite is produced by open-pit mining techniques, and most crude barite requires some upgrading to meet minimum purity or specific gravity levels.

Because of its high specific gravity, most barite (whether domestically mined or imported) is ground to a small uniform size for use as a weighting agent in petroleum well-drilling mud. Drilling mud is used in rotary drilling and pumped down through the drill pipe to remove rock cuttings and to lubricate the drill bit. Barite is added to increase the mud weight, which maintains the conditions necessary to prevent any gas, oil or saltwater from entering from high-pressure zones. Barite intended for this market must meet specifications set by the American Petroleum Institute.

The majority of U.S. barite grinding mills are located along the coast of the Gulf of Mexico, which allows convenient delivery of shipments from overseas suppliers. In the United States, about 95 percent of barite is consumed by petroleum well-drilling markets, and the remaining 5 percent for such industrial end-uses as barium chemicals, filler in paint and plastics, powder coatings, friction products (brake pads) for cars and trucks, and heavy aggregate for radiation shielding.

World barite production was about 8 million metric tons in 2005. China, India, the United States and Morocco, in descending order, were the leading producers and accounted for 85 percent of the total. Other significant producing countries included Iran, Mexico, Turkey and Vietnam.

Barite mining in the United States occurs predominantly in Nevada at three mines located in Elko and Lander counties, and some production is reported from a small barite mine in Georgia. In 2005, U.S. production was 489,000 metric tons and apparent consumption was nearly 3.1 million metric tons. Imports of crude barite totaled 2.57 million metric tons and were supplied by China (89 percent), India (10 percent), and Morocco (1 percent). Domestic consumption has increased by 60 percent since 2002 primarily as a result of the boom in exploration drilling for natural gas.

Worldwide, oil and gas drilling account for 85 to 90 percent of barite consumption. The non-drilling markets for barite are larger outside of the United States, particularly in China and Europe, which have significant production of barium chemicals. Data on non-drilling uses of barite are not readily available, but based strictly on increased drill rig activity, worldwide consumption of barite outside of North America is estimated to have increased in 2005. The areas that experienced the largest growth in the average number of drill rigs operating were Canada, the Far East and Latin America.

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

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