TRB Special Report 311: Effects of Diluted Bitumen on Crude Oil Transmission Pipelines (2013) / Chapter Skim
Currently Skimming:
3 Bitumen Properties, Production, and Transportation by Pipeline
3 Bitumen Properties, Production, and Transportation by Pipeline
Pages 22-50
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 22... ...
. Because only the Canadian bitumen is diluted for transportation by pipeline to the United States, it is the subject of the description in this chapter.1 Canadian bitumen deposits are concentrated in the Western Canadian Sedimentary Basin (WCSB)
|
From page 23... ...
The typical composition of the WCSB oil sands is 85 percent sand and clay fines,2 10 percent bitumen, and 5 percent water by weight.3 Oil sands also contain salts, trace gases, and small amounts of nonpetroleum organic matter.4 These components exist together in a specific microstructure with a film of water that surrounds each sand and clay particle, and the bitumen surrounds the film, as shown in Figure 3-1. When freed from this microstructure, bitumen has a typical elemental composition of 81 to 84 percent carbon; 9 to 11 percent hydrogen; 1 to 2 percent oxygen, nitrogen, and other elements; and 4 to 6 percent sulfur, most of which is bound in the bitumen in stable (e.g., heterocyclic rings)
|
From page 24... ...
Petroleum with a gas-free viscosity between 10,000 and 100 cp is generally termed heavy crude oil. In the absence of viscosity data, oil with API gravity less than 10 degrees is generally considered natural bitumen, whereas oil with API gravity ranging from 10 degrees API to about 20 degrees API is considered heavy crude oil.
|
From page 25... ...
, a Canadian heavy crude 7 API gravity values are referred to as "degrees." Most crude oils have API gravities in the range of 20 to 40 degrees, but some range 10 degrees higher or lower.
|
From page 26... ...
Although they are less viscous than bitumen, the heaviest conventionally drilled Canadian crude oils have relatively high viscosities as well.9 Several Canadian crude oils, including the Lloydminster crude oils shown in Figure 3-2, are routinely diluted with lighter oils to improve their flow in transmission pipelines.10 BITUMEN PRODUCTION The WCSB has long been a major oil-producing region of North America. Oil exploration commenced in the early 20th century, and by the 1960s hundreds of millions of barrels of Western Canadian crude oil were being exported each year through pipelines to the United States.
|
From page 27... ...
-- led to the recent growth in Canadian bitumen production for export to the United States. Indeed, no significant quantities of mined bitumen are diluted for pipeline transportation to the United States, the main market for bitumen recovered by using the SAGD process.12 Bitumen Mining and Upgrading to Synthetic Crude Oil About 20 percent of the bitumen deposits in the WCSB are less than 60 meters (200 feet)
|
From page 28... ...
The synthetic crude oils are also blended with other heavy Canadian crude oils, including in situ–produced bitumen, for pipeline transportation to the United States. Nearly all of the bitumen mined in the WCSB is upgraded to synthetic crude oil.14 This situation is subject to change as alternative methods are introduced to yield mined bitumen with reduced viscosity and water and sediment content comparable with that of the bitumen produced in situ and transported in diluted form through transmission pipelines.
|
From page 29... ...
At the surface, condensed water is separated from the recovered bitumen and recycled to produce steam for subsequent applications. 15 While asphaltene concentrations have significant implications for bitumen viscosity, the removal of all asphaltenes would not reduce viscosity enough for undiluted bitumen to meet pipeline specifications (Rahimi and Gentzis 2006)
|
From page 30... ...
than mined bitumen, and it is sufficiently stable for acceptance by long-distance pipelines. Whereas nearly all mined bitumen is upgraded into synthetic crude oil in Alberta, less than 10 percent of the SAGD-derived bitumen is processed In 2011, about 1.7 million barrels per day of bitumen were produced, with surface mining accounting 17 for 51 percent and in situ processes accounting for 49 percent of the production (ERCB 2013)
|
From page 31... ...
Department of Energy, imports of Canadian diluted bitumen and other crude oils have grown by more than one-third since 2000.18 Partially as a result of Canadian supplies as well as newly exploited domestic oil shale, crude oil imports from other regions of the world are declining. In particular, the Canadian feedstock has supplanted heavy crude oils once imported in large volume from Venezuela and Mexico (Figure 3-4)
|
From page 32... ...
refinery destinations for diluted bitumen and other Canadian crude oils, and Figure 3-6 shows the main pipeline corridors that access these refineries. Major export pipelines from Canada include the Enbridge Lakehead network, which serves several Great Lakes refineries; the TransCanada Keystone pipeline, which accesses the Cushing, Oklahoma, hub and refineries in southern and central Illinois; and the Kinder Morgan Express and Prairie pipelines, which transport Canadian crude oils to refineries in the Rocky Mountains and provide surplus to refineries farther east and south.
|
From page 33... ...
. Canadian heavy crude oils and diluted bitumen Refinery Storage hub Transmission pipeline Flow direction FIGURE 3-6 Main pipeline corridors moving Canadian crude oil to U.S.
|
From page 34... ...
. Some bitumen shipments are diluted with both condensate and synthetic crude oil to produce "dilsynbit." Dilution and blending activity is common in the petroleum industry, as distillates and light oils are regularly mixed with heavier oils to alter shipment density and viscosity characteristics.
|
From page 35... ...
In some cases, more diluent may be added after delivery to the transmission pipeline if further dilution is necessary to meet the density and viscosity levels required for long-distance transportation.22 Like all crude oil blending, the mixing of diluent and bitumen is designed to make the shipped product miscible, or fully mixed in all proportions. As discussed in Chapter 2, once in the pipeline, batch shipments of diluted bitumen and other heavy crude oils are sequenced to avoid contact with lighter crude oil and condensate shipments.
|
From page 36... ...
Illustrative blending ratios and resulting density and viscosity values for synbit and dilbit are given in Table 3-3. Once they are diluted for transportation, shipments of bitumen have physical properties comparable with those of other heavy crude oil shipments, and they can be stored and transported through the same pipeline facilities in a similar manner -- that is, without a need to heat the crude oil to increase fluidity.
|
From page 37... ...
] Synbit Bitumen 51.7 1,010 760,000 Synthetic crude oil 48.3 865 5.9 Total 100 940 128 Dilbit Bitumen 74.6 1,010 760,000 Condensate 25.4 720 0.6 Total 100 936 350 Source: Illustrative blending ratios provided by R
|
From page 38... ...
TABLE 3-4 Comparison of Density, API Gravity, and Viscosity of Diluted Bitumen and Other Canadian Crude Oils canadian heavy crude oils Western Bow Lloydminster Lloydminster Smiley– Canadian River Fosterton Blend Kerrobert Coleville Blend Density (kg/m3) 914 927 927 930 932 929 API gravity (°)
|
From page 39... ...
. Nevertheless, because the Canadian tariffs are generally more restrictive than those in the United States, it can be inferred that shipments of Canadian crude oils, including diluted bitumen, do not contain more water than other crude oils transported in U.S.
|
From page 40... ...
are available to compare diluted bitumen with other Canadian crude oils. Figure 3-7 shows the average sediment levels for nine diluted bitumen blends and 10 light, medium, and heavy Canadian crude oils.
|
From page 41... ...
. CCQTA data on the nature of solids filtered from five diluted bitumen and two heavy crude oil samples show median particle sizes that are comparable across the samples, ranging from 1.0 to 2.4 microns for four of the five diluted bitumen samples and from 1.9 to 2.3 microns for
|
From page 42... ...
The maximum particle sizes in the five diluted bitumen samples ranged from 11 to 92 microns, while the maximum value for the two heavy crude oils was 33 microns. Data are more limited for characterizing the shape, mass, and hardness of solids in diluted bitumen and other crude oils.
|
From page 43... ...
Table 3-6 shows the acidity and sulfur content for several sampled Canadian heavy crude oils and diluted bitumen blends. The acidity of crude oil is generally referenced by using total acid number (TAN)
|
From page 44... ...
The Canadian heavy crude oils and diluted bitumen contain 2.5 to 5 percent sulfur by weight. Whereas condensate and synthetic crude oils are largely free of sulfur (as shown in Table 3-2)
|
From page 45... ...
Available test data on the H2S content in crude oil indicate lower levels in diluted bitumen (less than 25 ppmw in liquid phase) than in other crude oils of various densities (Figure 3-9)
|
From page 46... ...
In general, flow velocities ranging between 0.75 and 2.5 meters per second would be expected to maintain turbulent flow in pipelines ranging from 8 to 48 inches in diameter when they transport crude oils with the range TABLE 3-7 Properties and Operating Parameters of Diluted Bitumen Shipments Reported by Five Canadian Pipeline Operators Lowest and Highest Range of Reported Values in Reported Highest Reported Property or Parameter Averages Normal Ranges Extremes BS&W (volume percent) 0.18–0.35 0.05–0.40 0.50 H2S (ppmw)
|
From page 47... ...
Nevertheless, the operators reported that because diluted bitumen and other crude oils enter the pipeline system deaerated, there should be no significant difference in the concentrations of oxygen and carbon dioxide gas in products transported in the same pipelines. Operators also reported that as a general matter they aggressively seek to limit avenues for air entry into the pipeline at all times, including periods of storage and blending and pumping operations.
|
From page 48... ...
While the sulfur in diluted bitumen is at the high end of the range for crude oils, it is bound in stable hydrocarbon compounds and is not a source of corrosive hydrogen sulfide. Diluted bitumen has higher total acid content than many other crude oils because of relatively high concentrations of high-molecular-weight organic acids that are not reactive at pipeline temperatures.
|
From page 49... ...
. Proc., 2012 Northern Area Eastern Conference: Corrosivity of Crude Oil Under Pipeline Operating Conditions, National Association of Corrosion Engineers International, Houston, Tex.
|
From page 50... ...
2004. Simple Tech niques for Evaluation of Crude Oil Compatibility.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.