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Oil Sand Kicks into High Gear PUBLIC ACCESS

New Extraction Technologies have Turned a Sticky Mixture into a Profitable Energy Source

[+] Author Notes

Associate Editor

Mechanical Engineering 120(12), 58-63 (Dec 01, 1998) (6 pages) doi:10.1115/1.1998-DEC-3

This article discusses the cutting-edge technologies and the rising value of light crude oils that have ushered in an era of new investment in Alberta’s oil sand extraction, with the major players embarking on ambitious programs that will more than double production in the next century. More recently, new extraction techniques and a rise in the price of light crude oils have made it more economical to extract the bitumen from sand and upgrade it into a light crude oil. Syncrude has undertaken a $6 billion (Canadian) project, Syncrude 21, to improve environmental performance and energy efficiency, while increasing product yield and quality. Syncrude expects to double its annual production to 155 million barrels by 2007, in part by opening its third mine at Mildred Lake. Suncor Energy also intends to increase its future production in its Project Millennium. The $2.2 billion (Canadian) endeavor is expected to boost oil sand production to 210,000 barrels per day by 2002, increasing current production by nearly two and a half times.

Beneath the windswept soil of the Canadian province of Alberta lies an unlikely-looking treasure. It is a thick, viscid mixture of bitumen, sand, clay, and water called oil sand that resembles asphalt to the untrained eye. However, to Syncrude Canada Ltd. and Suncor Energy In c., both headquartered in Fort McMurray, Alberta, it looks like gold. These two Canadian companies extract the bitumen from the sand, and upgrade it to light crude oils that are used to make fuels, petrochemicals, and lubricants.

Cutting- edge technologies and the rising value of light crude oils have ushered in an era of new investment in Alberta's oil sand extraction, with the major players embarking on ambitious programs that will more than double production in the next century.

Earlier in this century, oil sand was regarded more as a geological curiosity than as a valuable natural resource, because the high costs of mining oil sand and processing it hampered c0ITll11ercial-scale extraction. More recently, new extraction techniques and a rise in the price of light crude oils have made it more economical to extract the bitumen from sand and upgrade it into a light crude oil. In 1979, Syncrude and Suncor spent $25 (Canadian) to extract each barrel of oil from oil sand; by 1998, they halved that to approximately $13 (Canadian) per barrel.

Both companies mine the Athabasca Oil Sands in Alberta. As it was for the Beatles, 1964 proved to be a watershed year for oil sand extraction. Great Canadian Oil Sands Ltd., as Suncor was then known, began construction of its $240 million oil sand extraction plant, designed to produce 45,000 barrels of oil per day, and Syncrude Canada Ltd. was incorporated to exploit Alberta's oil sand deposits. Suncor completed the plant in 1967 and today produces more than 90,000 barrels of sweet crude oil, sour crude oil, and diesel fuel per day.

By 1978, Syncrude began producing from the Athabasca oil sand deposit a light, sweet crude oil called Syncrude Sweet Blend (SSB), which is used to make diesel, automotive, and aviation fuels, as well as industrial lubricants and petrochemicals. Syncrude produces 215,000 barrels of SSB daily.

Because of the technical improvements developed by these companies, oil sand extraction is a major component in Canada's energy industry, producing enough oil to meet 17 percent of the country's petroleum needs and accounting for 13 percent of all oil produced in Canada.

O&K and Syncrude engineers designed the RH400 hydraulic excavator, believed to be the world's largest, to deposit 80 tons of oil sand in a single pass in 28-to 30-second cycle times.

Grahic Jump LocationO&K and Syncrude engineers designed the RH400 hydraulic excavator, believed to be the world's largest, to deposit 80 tons of oil sand in a single pass in 28-to 30-second cycle times.

Oil extraction begins with mining techniques, specifically, removing the layers of earth and overburden (a thick layer of clay, silt, and gravel) to expose the oil- laden sand. At its Mildred Lake mine, Syncrude uses two 8750 walking draglines made by Marion Power Shovel, and two 2750 walking draglines made by Marion's parent company, Bucyrus International Inc. in Milwaukee, all 28,000- horsepower machines, to dig out the oil sand. The walking draglines are equipped with 90-cubic-yard buckets on 360-foot booms. The dragline operator piles oil sand in windrows along the sides of the mine pit.

Four Krupp bucketwheel reclaimers scoop the oil sand from the windrows and deposit it onto conveyors that transport it to Syncrude's extraction plant. Three of the 12,000-hp re claimers have wheels equipped with 14 buckets that each hold 3.1 cubic yards of sand. One has a "flying wheel" that carries 24 buckets, each capable of holding 1.8 cubic yards of sand. The conveyor belts carry more than 6,300 metric tons of oil sand per hour 31 miles from the mine and an additional 1.2 miles in the extraction plant.

The operator of this Bucyrus International 2750 walking dragline piles the oil sand excavated from Syncrude's Mildred Lake mine in wind rows along the sides of the mine pit. Reclaimers then deposit the sand on conveyors.

Once inside the extraction plant, the oil sand is sent into large, horizontal, rotating drums called tumblers. Caustic soda, hot water, and steam are introduced to the oil sand, which is rotated to aerate the mixture. The slurry is then discharged onto vibrating screens that remove clay and rocks. The filtered slurry is diluted in pump boxes and pumped to the primary separation vessels, or PSVs.

Bitumen floats to the surface within the PSVs and is separated. The sand settles to the bottom of the PSVs and is pumped to tailings oil recovery (TOR) vessels.

Much of the bitumen remaining in the sand is removed in the TOR vessels by a proprietary Syncrude technology. The bitumen separated in the TOR vessels returns to the separation vessels to improve its quality. The bitumen froth is then collected and deaerated. Naphtha is added to assist with the removal of the remaining solids and water in second-stage extraction.

Syncrude added an extraction auxiliary production system at the site in 1993. This system takes the crushed oil sand excavated by auxiliary production and sends it to a cyclofeeder, where it is mixed with caustic soda and water.

Screens filter out oversize particles before the slurry is piped to the extraction plant, and to the PSVs for processing.

The clay, hydrocarbons, sand, and water that remain after extraction are stored in a settling basin that measures 22 square kilometers. Water is removed and then reused as process water.

Altogether, the company processes 440,000 metric tons of oil sand per day to produce 500,000 barrels of diluted bitumen, representing a recovery rate of over 90 percent of the bitumen contained in the oil sand.

Diluted bitumen leaving the extraction plant enters a diluent recovery unit where it is heated to 110°C. Approximately 60 percent of the water and naphtha flashes off as vapor in the unit's first-stage flash drum and leaves the drum through an overhead line. Bitumen exits the drum through a bottom line and is heated in a second flash drum, this time to 150°C. The second heating removes all the remaining water and most of the remaining naphtha as vapor.

The vapors from both flash drums condense in overhead coolers and collect in a condensate drum. Bitumen from the second-stage flash drum is heated to 306°C in a furnace and sent into a fractionator. All remaining naphtha leaves the bitumen in the fractionator, cools to 118°C, and condenses for collection in an overhead accumulator. The naptha returns to the extraction plant for reuse.

Bitumen from the bottom of the fractionator proceeds to two fluid cokers and an LC-Finer. The LC-Finer adds hydrogen over an ebulated catalyst that causes the bitumen to break down, producing a cracked light gas oil.

The unit was designed to process 40,000 barrels of bitumen per day, a total raise d to 60,000 barrels per day by improvements that removed various bottlenecks. Residues from the LC-Finer are sent to the fluid cokers to be mixed with bitumen.

The fluid cokers were originally designed to process 72,900 barrels of bitumen daily, but Syncrude engineers have improved their performance to the point that they routinely process more than 110,000 barrels a day. The 510°C bed temperatures within the cokers crack the long bitumen molecules. This causes the lighter naphtha and gas oil, used to make crude oil, to separate from the heavier carbon. The carbon forms coke granules that go into a burner chamber. Some of the coke burns to provide the heat for the cracking process, while the remainder is stored in the mined-out pit for future use.

The cracked bitumen divides into raw naphtha, and light and heavy gas streams that react with hydrogen in hydrotreater units at high temperatures and pressures in the presence of a catalyst. The hydrotreaters remove sulfur and nitrogen, and blend the three streams together to form a light, sweet crude oil. Sulfur converts to an elemental form, which is made into blocks or shipped to fertilizer plants to make sulfuric acid. The nitrogen is removed as ammonia and burned in the carbon monoxide boiler in the mine's utilities plant, which provides the air, electricity, heat, nitrogen, and steam for operations.

The fuel gas that is a byproduct of the refining process is sent to a mine unit that removes hydrogen sulfide. The sweet gas this generates fuels the upgrading process and the utilities plant.

The naphtha and gas oils leaving the hydrotreaters are blended to make the high-grade crude oil known as Syncrude Sweet Blend. Sixty percent of this goes to Edmonton for further processing, 30 percent to the midwestern United States, and 10 percent to markets in eastern Canada.

In its own operations at Steepbank, Suncor uses Marion 351 and 301 cable shovels, which are capable of digging up to 80 tons at a time, and three Sl1uller Demag hydraulic shovels that can dig up to 30 tons at a time, to load about 170,000 tons of oil sand a day into 16 Caterpillar 793C mining trucks . Each truck can haul up to 240 tons. The ore goes to a sizing plant, where two MMD 1500 crushing l11.achines made by Mining Machinery Development (MMD) in Somercotes, England, reduce up to 12,000 tons per hour. Five kilometers of conveyor belt transport more than 7,000 tons of crushed ore per hour to the extraction plant.

The ore enters five Allis Chalmers conditioning drums that rotate as hot water and steam are added to separate the bitumen, sand, and clay. Each drum can process up to 2,000 tons of oil sand per hour. Separation cells cause the sand to settle to the bottom and the bitumen to float to the surface as a thick froth. This froth is diluted with naphtha to facilitate pumping and cleaning.

Diluted bitumen is sent through centrifuges to remove the remaining minerals and water. Water, clay, sand, and residual bitumen are pumped to holding ponds, where the clay and sand settle to the bottom. The water is recycled back to the extraction plant.

The naphtha is removed and recycled for further extraction. The diluted bitumen is piped to the upgrading plant for heating in coke furnaces that raise its temperature to 500°C. The heated bitumen is sent to coke drums, which separate the bitumen into coke and hydrocarbon gases. Some of the coke fuels the site's utilities plant, while the remainder is stockpiled for future use.

Hydrocarbon gases are sent into a fractionator for separation into naphtha, kerosene, and gas oil. Suncor produces more than 26 million barrels of oil products, blended to meet customer specifications, which move via pipeline to Edmonton for distribution to markets across Canada and the United States.

Building Syncrude's cyclofeeder within a tight deadline was like constructing a ship in a bottle.

Suncor uses this MMD 1500 crushing machine to reduce 12,000 tons of oil sand per hour before conveying it to the extraction plant.

Grahic Jump LocationSuncor uses this MMD 1500 crushing machine to reduce 12,000 tons of oil sand per hour before conveying it to the extraction plant.

Syncrude has undertaken a $6 billion (Canadian) project, Syncrude 21, to improve environmental performance and energy efficiency, while increasing product yield and quality. Syncrude expects to double its annual production to 155 million barrels by 2007, in part by opening its third mine at Mildred Lake.

The first portion of Syncrude 21 involved using trucks and shovels to begin excavation of the new North Mine at the close of September 1997 and use of a full-scale hydro-transport process developed by Syncrude at the site. This process was designed to improve reliability and to cost less than the draglines, bucketwheel reclaimers, and conveyors used in the base mine at Mildred Lake. In addition, the colossal scale of the process required the use and development of some of the world's largest mining equipment.

Up to 20 Caterpillar 793B trucks, one Caterpillar 793C truck, and eight Haulpak 930E trucks are used to transport excavated oil sand. The CAT 793B and 793C trucks are 240-ton machines, while each of the Haulpaks, the world's largest mining trucks, can transport 320 tons of excavated sand. Fittingly, the Haulpaks are filled by what is believed to be the world's largest hydraulic excavator, the O&K RH400. This machine was designed by engineers from O&K Mining GmbH in Dortmund, Germany, working jointly with their counterparts at Syncrude.

The primary challenges to the RH400 designers included the very scale of the excavator, which had to deposit 80 tons per pass with 28- to 30-second cycle times. The oil sand itself posed difficulties beyond conventional hardrock mining. Oil sand is more abrasive and dense, and it becomes wet and sticky in the summer. Unlike hardrock mining, where blasting rolls material toward the excavator, oil sand remains in place without the benefit of free fall.

The O&K and Syncrude designers answered these needs by building a 42-cubic-meter bucket that can be expanded to 43.5 cubic meters, to achieve an ultimate truck fill factor accommodating material variances and other conditions. "We also increased the negative cud on the bucket and adjusted the bucket's rotation on its attachment to enable it to dig out oil sand more effectively," explained Bill Mateychuk, president of O&K's Canadian branch in Edmonton.

Procuring the power plant for the big rig hit a snag. "Our design engineers had designed the RH400 to use two new 2,000-hp Cummins QSK60 engines, but Cummins had not finished field testing them by our deadline. We were forced to go to twin 1,675-hp Cummins K2000E engines, the second of which we reworked to provide 1,825 hp," said Mateychuk. He added that in October 1998, the K2000Es in the first of the two RH400s sold to Syncrude were replaced with QSK60 engines.

Although the RH400 was targeted to the Syncrude operation, it is intended to serve other world mining markets, said Mateychuk. He noted that the hydraulic excavator is well suited for ore extraction in Australia, South America, and South Africa.

Syncrude's mining trucks deliver their cargoes to one of two crusher stations at the North Mine. A double-roll crusher/feeder/breaker breaks down as much as 6,000 metric tons of oil sand per hour. The crushed sand moves to a surge facility, where two apron feeders direct the sand to the cyclofeeder that separates bitumen from the sand.

Syncrude first designed and built a pilot plant using the new cyclofeeder technology. The cyclofeeder mixes hot water with the oil sand to create a slurry that i pumped through a 27-inch transport pipe to the extraction plant. The full-scale cyclofeeder was constructed by Lockerbie & Hole Contacting Ltd. in Edmonton.

"Syncrude awarded Lockerbie the contract in January, and wanted the unit up and running in August. The tight deadline was a major challenge to building the cyclofeeder," recalled Hans Wolf, a civil and mechanical engineer and senior project manager at Lockerbie & Hole. Wolf, an ASME member, said that his company's experience in building unconventional equipment, such as vessels for biomass conversion and waste oxidation, served it well for the unique Syncrude project.

"For example, Syncrude ordered high-tensile strength and yield steel pipe for the cyclofeeder. Because the pipe would be carrying a slurry, conventional 90-degree elbow joints could not be used; instead, they required sweeping bends, which curve gradually," said Wolf. The pipe was cast in South America, had its interior armored in Texas, and was bent in Calgary. Because of the time-consuming, demanding logistics the process entailed, Lockerbie had to rework its construction schedule. "It was like constructing a ship in a bottle," said Wolf.

Lockerbie & Hole also brought its considerable fabrication experience to the cyclofeeder. "Rather than use construction cranes to lift a single, large piece of equipment into place, we would break it down and use the overhead maintenance cranes Syncrude provided to hoist the pieces," explained Wolf. Lockerbie & Hole completed the cyclofeeder to commence operations in August 1997.

A booster pump house helps drive the cyclofeeder slurry through the pipeline. A second production train at the North Mine is scheduled to be completed by 1999. It will use trucks, shovels, cyclofeeder, and hydro transport systems similar to the first North Mine production train.

Five Kilometers of conveyor belt at the Suncor mining site transport more than 7,000 tons of crushed ore per hour to the extraction plant.

Grahic Jump LocationFive Kilometers of conveyor belt at the Suncor mining site transport more than 7,000 tons of crushed ore per hour to the extraction plant.

Suncor Energy also intends to increase its future production in its Project Millennium. The $2.2 billion (Canadian) endeavor is expected to boost oil sand production to 210,000 barrels per day by 2002, increasing current production by nearly two and a half times. Project Millennium involves expanding Suncor's new Steepbank mine to the east and south to extend its life through 2026. The Steep bank Dune was commissioned in August 1998 and is expected to increase production to 105,000 barrels per day by the end of 1998. The Steepbank project has involved the purchase of additional mine equipment and some retrofitting of existing equipment, according to Mario DeCrescentis, a mining engineer and director of bitumen production at Suncor.

"For example, we have added two more MMD crushers to process the oil sand from the Steepbank expansion, and we will be using up to 50 Caterpillar trucks capable of hauling 360 tons of sand," said DeCrescentis. Suncor will also replace its 30-year-old conditioning drums, which are expensive to maintain, with McClennahan rotary breakers. These machines break coal. "They function similarly to the drums, but are equipped with screens rather than shells. We will feed crushed oil sand into the breakers, mix it with hot water to form a slurry, and pump it via a hydro transport pipeline to a new primary extracting plant we are constructing on the eastern banks of the Athabasca River," explained DeCrescentis.

Suncor's energy services department installed a flue gas limestone scrubbing system in 1996, which uses a limestone slurry to remove 95 percent of the sulfur from the coke, which it burns as fuel. "One of the byproducts of this process is gypsum, which we add to our fine tailings to stabilize them," said DeCrescentis.

Engineers from Babcock & Wilcox in Cambridge, Ontario, are modifying the Foster Wheeler coke-fired boilers. "Their capacity is being increased from 750,000 pounds of steam per hour to one million lbs./hr. by the replacement of division walls with screen walls, the addition of a larger superheater, larger steam and mud drums with increased generating bank surface, and the addition of an economizer," said Rick Speers, a mechanical engineer and director of Energy Services Projects at Suncor.

When Project Millennium proceeds, additional boilers will be added at the utilities plant and two will be added to the new extraction plant located on the east side of the Athabasca River. Adding two 85-megawatt gas turbines that operate in a cogeneration assembly will meet type demand for more electricity.

Suncor also built some major infrastructure to accommodate its new Steepbank mine. "We built a bridge across the Athabasca River, capable of supporting 240-ton trucks, in 14 months," recalled DeCrescentis.

The increased production and reduced costs of oil sand extraction bode well for this Canadian industry. These factors are also buttressed by the abundance of future supplies·. According to the Alberta Energy and Utilities Board, the regulatory authority of the Athabasca Oil Sands, Alberta's oil sand deposits contain 1. 7 trillion barrels of bitumen.

Current technologies can recover 300 billion barrels of that amount, while l1uning can recover another 30 billion from a source closer and less volatile than the Middle East.

This Marion 301 cable shovel deposits oil sand into a Dresser Haulpak mining truck for transport to Suncor's sizing plant, where the ore will be reduced for further processing.

Grahic Jump LocationThis Marion 301 cable shovel deposits oil sand into a Dresser Haulpak mining truck for transport to Suncor's sizing plant, where the ore will be reduced for further processing.

Copyright © 1998 by ASME
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