Production Process Video
Mining
Syncrude currently mines oil sands from two mines: The North Mine, located near the Mildred Lake site, and the Aurora North Mine, located 35 kilometres northeast of the base operations site. During 2006 and 2007, ore extraction was phased out of Syncrude’s original Base Mine. The mining and extraction methodologies utilized at Syncrude have evolved over time as technological innovation has been continuously introduced. The initial mining operations were based on the use of very large draglines, bucket-wheel excavators and long conveyor systems. These original systems have, for the most part, been retired in favour of new technologies. The current mining operations utilize very large shovel excavators and mining haul trucks. This technology, now the standard in the oil sands mining industry, is known as "truck and shovel" mining. The larger shovels can excavate 100 tonnes in a single pass and the larger haul trucks can carry 400 tonnes of material from the mine face to the dumping location. A fleet of 15-20 shovels and 80-90 haul trucks are used in the overburden and oil sands ore mining operations at Syncrude.
The Base Mine began operations in 1978 and was closed in 2007. The North Mine began operations in 1997 and Aurora North Mine in 2000. The Aurora North Mine is comprised of Leases 10, 12 and 34. The Aurora North Mine operations use a new generation of larger 400-tonne trucks and larger shovels. The Aurora North mine contributed 55 per cent of the total bitumen produced from Syncrude in 2007 (2006 – 58 percent) and the North mine contributed 45 per cent (2006 – 31 per cent). The Base Mine did not contribute any bitumen in 2007 (2006 – 11 per cent).
It is important to note that mining operations not only deal with oil sands excavation and delivery to extraction operations but also with overburden removal and disposition. Overburden is the sand and clay material found above the oil sands bearing layer in the Athabasca oil sands formations. It must be removed in order to expose the oil sands bearing layers for mining. In 2007, the total volume of overburden mined was approximately 226 million tonnes compared to 214 million tonnes in 2006.
Since its completion in 2005, the South West Quadrant Relocation project has added a supplemental mining system at the North Mine, feeding the existing Mildred Lake extraction plant; integrated a third material handling train into the Aurora North mine in addition to the existing two full trains of mining and extraction systems; increased the effective utilization of the two existing Aurora North bitumen production systems; and provided additional thermal energy sources at Aurora North by adding a second 80MW gas turbine generator and heat recovery hot water generator. This additional mining capacity has served to offset the phased out production from the Base Mine.
Extraction
Historically, all extraction activity occurred at the Mildred Lake plant as the ore was mined exclusively at the Base Mine. As part of the transition from the Base Mine to the North Mine and subsequently to the Aurora North Mine, the method of extraction and the location of extraction facilities have changed.
The ore from the Supplemental Mining System at the North Mine is delivered to the Mildred Lake extraction facilities by conveyor and is then mixed with steam, hot water and caustic soda to produce slurry at a temperature of approximately 80C. This mixing process occurs in large horizontal rotating tumblers that condition the mixture for separation. This slurry is discharged from the tumblers onto vibrating screens to remove large rocks and lumps of clay prior to entering the primary separation vessel, where the floated bitumen is recovered. Much of this system continues to operate today.
At the North Mine, the ore is crushed in a double roll crusher, and conveyed to a cyclofeeder where it is mixed with warm water and caustic soda to produce a slurry at a temperature of approximately 50C. The use of warm water in this process as opposed to hot water at Mildred Lake has led to decreases in energy consumption in this part of the operations. The resulting slurry is screened, and the oversized material is rejected for further crushing and reprocessing. The slurry is further conditioned as it is transported to the Mildred Lake extraction plant via a hydrotransport pipeline where it enters the primary separation vessels.
At the Mildred Lake extraction plant, the slurry from the North Mine flows into primary separation vessels and further separation takes place. The resulting froth is then mixed with the froth from the Aurora North Mine and diluted with naphtha prior to further processing. A final stage of separation removes substantially all of the remaining water and clay fines, leaving a relatively clean bitumen as the feedstock for the upgrader.
The extraction process at the Aurora North Mine is similar to the North Mine, with a few exceptions. After the ore is crushed in the double roll crusher, it is conveyed to a mixbox where it is mixed with water to produce a slurry with a temperature of approximately 35C. Rather than shipping the oil sands slurry to the Mildred Lake extraction plant, the slurry is transported via a hydrotransport pipeline to one of two primary separation vessels located at the Aurora North Mine (approximately three to five kilometres from the mining area). Here, the sand settles to the bottom of the vessel and is transferred to the Aurora North Mine's tailings pond. The primary froth rises, is recovered and is then piped to Mildred Lake for further processing.
The material remaining after the bitumen is extracted from the oil sands consists of water, sand, fine clay particles and some residual hydrocarbons. This material is sent to a tailings settling basin where the solids settle to the bottom and the clarified water is recycled for re-use in the extraction process. The rate at which the fine tailings settle out of the water is extremely slow and is the subject of considerable research and development activity to identify the most cost effective and environmentally acceptable disposal method. A new composite tails technology using the mature fine tailings from the settling basin to create solid, permanent landscapes in mined-out areas began application at the Mildred Lake site during 2000. The key tailings research and development initiatives proposed for the next few years include: optimization of the composite tailings process, reclamation of tailings deposits, managing recycle water chemistry and development of thickened tailings for oil sand application.
One of the key performance metrics associated with the extraction operation is known as "recovery". Recovery measures the volume of bitumen recovered from the oil sand as a per cent of the oil that was contained in the oil sand processed in the extraction plants. In 2007, this recovery factor was approximately 92 per cent (2006 – 90 per cent). Improvements in extraction recovery ratios year-over-year are the result of continuous improvement initiatives undertaken by Syncrude.
Upgrading
Upgrading is the final stage in which the bitumen is converted into SCO. The first step in upgrading is the removal of the diluent naphtha which was added in the extraction plant. This naphtha is recycled to the froth treatment plant for re-use. Next, the bitumen is fed through a vacuum distillation unit in which lighter fractions of hydrocarbons are removed for further processing, as discussed later. The heavier bitumen components are processed in three fluid cokers and one LC Finer. While these two forms of upgrading bitumen are somewhat different, they have the same intended purpose, namely to break down the heavier hydrocarbon components into lighter components. The lighter hydrocarbons separated in the vacuum distillation unit are "by-passed" around the cokers and the LC Finer because they are already of sufficient quality to be processed directly in secondary upgrading process units. The vacuum distillation unit had a nominal capacity rating of 180,000 bbls/d of bitumen feed until, in the fourth quarter of 2005, its capacity was expanded as part of the Stage 3 expansion to about 285,000 bbls/d.
Fluid coking involves the thermal cracking of bitumen molecules into lighter components. The by-products of this process include petroleum coke, CO gas and off gas. CO gas is used as fuel in CO boilers to generate steam and power for the facility. Off gas is used as fuel in the upgrader. The residual coke produced in the coker is slurried into segregated cells in the tailings pond. The two original fluid cokers have been expanded in capacity over the years and, in 2007, each had a nominal capacity rating of approximately 105,000 bbls/d of a 50/50 mix of bitumen and heavier vacuum topped bitumen feed. This capacity was unchanged from the prior year. The third fluid coker, added in 2006 as part of the Stage 3 expansion, has the same purpose as the original two cokers but is designed to process 95,000 bbls/d of 100 per cent vacuum topped bitumen.
The LC Finer cracks bitumen molecules into lighter components via the addition of hydrogen and in the presence of a catalyst. This unit does not convert all of the bitumen to light products. An unconverted residual stream also is produced and this stream is sent to the fluid cokers to supplement the feed to those units. In 2007, the LC Finer unit had a nominal capacity rating of approximately 50,000 bbls/d of a 60/40 mix of bitumen and vacuum topped bitumen feed. This capacity was unchanged from the prior year.
One of the key performance metrics associated with the upgrading operation is referred to as "yield". Yield measures the volume of finished products produced per volumetric measure of bitumen feedstock. In 2007, the upgrading yield was approximately 84 per cent, basically unchanged from 2006.
The lighter hydrocarbon components produced by the three fluid cokers, the LC Finer, and those removed in the vacuum distillation unit are then sent to hydroprocessing units for further clean up, particularly for the removal of sulphur and nitrogen. Hydrotreating involves the removal of sulphur and nitrogen compounds via the addition of hydrogen in the presence of a catalyst. The hydrotreated components are then blended together into SCO. This SCO product contains no residuum and is low in sulphur, providing an attractive feedstock to refineries. With Stage 3 complete, the productive capacity of the upgrader rose to 129 million barrels of SCO per year by the end of 2006 (unchanged for 2007) compared to 90 million barrels of SCO per year in 2005. Actual production of SCO in 2007 was 111 million barrels, a significant increase from prior years. Production of SCO was 94 million barrels in 2006 and 78 million barrels in 2005.
With the start up of the new Stage 3 plants in August 2006, the quality Syncrude’s finished synthetic crude oil blend was improved and re-designated SSP, short for Syncrude Sweet Premium. SSP is designed to have a diesel cetane number of approximately 38, up from the previous number of approximately 33, and the jet smoke point of approximately 19, up from 16. Our recent expectation was that the quality transition to SSP would occur in 2008 following repairs to the new hydrogen plant. However, the transition occurred in 2007, earlier than expected, as a result of the removal of some hydrogen constraints on various units. New hydrogen plant repairs are still expected to occur in 2008 to secure additional hydrogen feedstock for the continued production of SSP for when the operations reach design capacity rates.
Utilities and Offsites
The utilities plants are tasked with producing steam, electricity, air and water for the mining, extraction and upgrading plants. These commodities are often generated from fuels and heat produced as by-products in the major operating areas or from purchased energy sources such as natural gas or electricity.
Syncrude operates utility plants located both at the base Mildred Lake site and at the Aurora site. Energy systems are highly integrated at the Mildred Lake site, taking advantage of the heat generated in the upgraders and moving that energy to the energy-consuming plants in mining and extraction. At Aurora North, natural gas is purchased to provide the required utilities. Syncrude owns and operates two large gas turbine generators at Aurora North to provide both the required steam and power for the plants.
One of the key performance metrics associated with the integrated Syncrude operation is the "energy intensity". Energy intensity is measured in many ways in the industry but in Syncrude's case it is the amount of purchased energy consumed per barrel of SCO. In 2007, the purchased energy intensity was 0.84 GJ per barrel compared to 2006 which was 0.98 GJs per barrel. The increased consumption of 0.98 GJ’s per barrel in 2006 was attributable to increased bitumen volumes sourced at the Aurora mine, and increased use of purchased natural gas for items such as steam generation during start-up of the Stage 3 facilities, which are highly integrated. The 2007 energy intensity reflects a full year of Stage 3 volumes. We estimate that long-term consumption going forward will be about 0.85 GJs per barrel as additional hydrogen, which is derived from natural gas, is used to produce the higher quality SCO and as bitumen is increasingly sourced from the Aurora mine. The Aurora mine relies mainly on purchased natural gas for its energy needs as process heat from the upgrader is unavailable due to the mine’s remoteness from the Mildred Lake plant. Purchased natural gas prices decreased to $6.14 per GJ in 2007 compared to $6.26 per GJ in 2006.
Natural gas, used by Syncrude to fuel operating plants and as feedstock in the production of hydrogen, is transported to Syncrude from Alberta's gas production and transmission infrastructure through dedicated pipelines. The gas is purchased from producers under various supply contracts to manage Syncrude's requirements. This pipeline and storage infrastructure has been expanded in the Athabasca region in recent years to improve the overall deliverability and reliability of the supply system.
Off-sites are generally referred to as those facilities required to support the operation of the main processing plants. These facilities include product storage tank farms, waste water collection and handling systems and flares. Many of these facilities were expanded as part of the Stage 3 expansion project.
Syncrude operates a utility plant at its Mildred Lake site using refinery off gas, produced from the upgrading operation, augmented with natural gas. When operationally and economically desirable, Syncrude purchases power from, or sells power to, the Alberta electric power grid. Syncrude also owns two 80-Megawatt gas turbine power plants at the Aurora North mine site that provide electrical and thermal energy for the Aurora North mine operations. These plants are connected with the Mildred Lake facilities. The Aurora Thermal Block ("ATB") which consists of two hot water generators, has been in operation since mid-2004. The ATB facilities provide hot water generating capacity at Aurora North and allow the extraction process to operate at the required 35 degrees celsius temperature.
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