Over the past decade, production of “unconventional” oil in North America has surged as technological improvements and cost reductions have made these crudes competitive in the North American market. Unconventional oil in North America derives from two sources. In the U.S., hydraulic fracturing technologies have been widely applied to extract oil from shale formations or other typically inaccessible, low-permeability rocks. In Canada, petroleum products have been extracted from “oil sands” or “tar sands.” Together, these streams have increased North American production of crude oils by 46% since 2008.4
The oil sands yield bitumen, a highly viscous form of petroleum that is produced by surface mining or by in situ recovery. Surface mining is preferred for deposits within 75 m of the surface.5 In situ recovery, in which steam is injected to mobilize bitumen underground, is used for deeper deposits. Production of bitumen is predicted to increase 2.5-fold from 2013 to 20305a although future production trends may be influenced by declining crude prices in world markets.
After separation from the host rock, bitumen is modified for transport. Commonly, it is combined with lower-density hydrocarbon mixtures (condensates, synthetic crude, or a mixture of both) to obtain a product with an acceptable viscosity and density for transport to refineries via pipeline. This engineered fluid is referred to as diluted bitumen. Common names refer to subtypes (e.g., dilbit, synbit, railbit, and dilsynbit) but, for
FIGURE 1-1 Existing and proposed Canadian and U.S. crude oil pipelines.
SOURCE: Canadian Association of Petroleum Producers5a
simplicity, the term diluted bitumen as used in this report encompasses all bitumen blends that have been mixed with lighter products.
Diluted bitumen has been transported by pipeline in the U.S. for more than 40 years, with the amount increasing recently as a result of improved extraction technologies and resulting increases in production and exportation of Canadian diluted bitumen. The increased importation of Canadian diluted bitumen to the United States has strained the existing pipeline capacity and contributed to the expansion of pipeline mileage over the past 5 years. Although rising North American crude production has resulted in greater transport of crude oil by rail or tanker, oil pipelines continue to deliver the vast majority of crude oil supplies to U.S. refineries. Most of the pipeline systems that are currently transporting diluted bitumen originate near extraction sites in Alberta, Canada (see Figure 1-1). To accommodate increased export volumes, additional pipelines are being proposed and developed. Proposals include (i) the Keystone XL.,i which would deliver diluted bitumen to Cushing, Oklahoma, in the U.S.; (ii)
i President Obama announced on November 6, 2015 the decision to deny a Presidential Permit for the construction of the Keystone XL Pipeline.
the Energy East, which would transport products to eastern Canada and its refineries; (iii) the Northern Gateway (“Enbridge Gateway” in Figure 1-1); and (iv) the Kinder Morgan Trans Mountain (“TM Expansion” in Figure 1-1). Both of the latter pipelines would transport products within Canada from Alberta to West Coast terminals.
In the event of a spill, impacts and cleanup procedures depend strongly on the environmental setting. Figure 1-1 indicates that the transmission pipelines transporting diluted bitumen are currently located onshore, which includes passage across terrestrial and freshwater environments, and near shore, which includes the marine waters near the coastline. Deepwater environments are not presently pertinent to pipeline transport of diluted bitumen and are not considered in this report.
In January 2012, the Secretary of Transportation was tasked by Congress to “determine whether the regulations are sufficient to regulate pipeline facilities used for the transportation of diluted bitumen . . . and whether any increase in the risk of release exists for pipeline facilities transporting diluted bitumen.”2 The U.S. Department of Transportation’s (USDOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) contracted with the National Academies of Sciences, Engineering, and Medicine (the Academies) to assemble a committee of experts to analyze whether the likelihood of release was greater for the transportation of diluted bitumen compared to that for other commonly transported crudes via U.S. transmission pipelines.2 An expert committee completed a comprehensive analysis and review of the available data on the chemical and physical properties of shipments of diluted bitumen and other crudes, examined pipeline incident statistics and investigations, and consulted experts in pipeline corrosion, cracking, and other causes of releases. The analysis covered many aspects of pipeline transportation including an explanation of the U.S. pipeline system; pipeline construction, maintenance, and alerts; incident data reported to PHMSA; and a discussion of bitumen production. Ultimately, after detailed analysis, the committee report, issued in 2013, “did not find any causes of pipeline failure unique to the transportation of diluted bitumen.”2 Environmental consequences of spills of diluted bitumen from pipelines were not within the scope of the Effects of Diluted Bitumen on Crude Oil Transmission Pipelines report. Following the release of the 2013 study, Congress tasked USDOT in 2014 to undertake a study to better understand the environmental impacts of spills of diluted bitumen from transmission pipelines and the adequacy of spill response planning.3
Based on this direction from Congress, PHMSA returned to the Academies with a request to assemble an ad hoc committee to analyze whether the relevant properties of diluted bitumen differ sufficiently from those of other crude oils commonly transported in U.S. transmission pipelines to warrant modifications of the regulations governing spill response plans, spill preparedness, and/or cleanup. The committee’s statement of task is provided in Box 1-1. This report focuses primarily on spills of crude oil from U.S. transmission pipelines. Over the course of producing this report, however, it became clear that the utilization of other modes of transportation for crude oil such as rail, truck, and tanker have increased and are worth consideration. While this report does not address any of the particular aspects of those transportation modes, many of the environmental effects of spilled oil are independent of the method of transporta-
Statement of Task
An ad hoc committee will analyze whether the properties of diluted bitumen differ sufficiently from those of other crude oils commonly transported in U.S. transmission pipelines to warrant modifications of the regulations governing spill response plans, spill preparedness, or cleanup.
The committee will
- Review the available literature and data, including any available data from oil spill responses or cleanup, to determine the current state of knowledge of the transport, fate, and effects of diluted bitumen once spilled into the environment (onshore and offshore);
- Identify the relevant properties and characteristics that influence the transport, fate, and effects of commonly transported crude oils, including diluted bitumen, in the environment;
- Make a comparison of the relevant properties identified in item 2 between diluted bitumen and a representative set of crude oils that are commonly transported via pipeline; and
- Based on the comparison in item 3, analyze and make a determination as to whether the differences between the environmental properties of diluted bitumen and those of other crude oils warrant modifications to the regulations governing spill response plans, spill preparedness, or cleanup.
If the committee finds that there is not sufficient information to make a comparison of the environmental properties between diluted bitumen and other crude oils, the committee may make recommendations as to the additional data that would be needed to make such a determination.
tion and therefore this report can provide useful insight into areas beyond pipeline transportation.
To understand the potential consequences of spills of diluted bitumen, knowledge regarding its chemical properties and environmental behavior during and after a spill in various spill environments is required. To date, several reports have been published that examine the properties,6 toxicity,7 and composition of diluted bitumen products derived from the Canadian oil sands.8 Other recent reports focus on the behavior and fate of spills in marine5b,8-9 and freshwater environments.5b,9a,10 Many of these reports were prepared as a result of the release of diluted bitumen into the Kalamazoo River by a break in the Enbridge 6B pipeline in Marshall, Michigan, on July 25, 2010. The total release was estimated to be 843,444 gallons, one of the largest freshwater oil spills in North American history, with cleanup costs exceeding $1.2 billion.11 The Marshall release attracted attention because of the broad extent and consequences of the release and the unprecedented scale of impact.12 The data and information gathered from experts and reports have been critical to addressing the statement of task and supporting the recommendations found herein. Nonetheless, the current knowledge base is limited, and a better understanding of the chemical constituents and behavior of diluted bitumen spills in diverse environmental settings would be helpful to inform response plans and actions.
To make a comparative analysis of diluted bitumen and crudes commonly transported by U.S. transmission pipelines, the committee gathered information from a variety of experts and stakeholders from government, nongovernmental organizations (NGOs), industry, and academia. A list of those experts and stakeholders can be found in the Acknowledgments. Technical information on properties of crude oil and on the behavior, fate, and environmental impacts of spills of diluted bitumen was provided directly or presented during one of several data-gathering meetings. In addition, discussions with agencies, individuals, and groups concerned with development of plans for responses to oil spills were extremely valuable. A subgroup from the committee conducted a site visit to the incident command post for the Refugio spill in Santa Barbara, California, in May 2015 to observe a response in action and to hold discussions with participants. A questionnaire requesting data was submitted to the American Petroleum Institute (API) and to the Association of Oil Pipe Lines (AOPL)
with a request for help obtaining data from the pipeline industry but drew no response.
In 2013, the United States produced 2,720 million barrels13 of crude oil, an increase of about 35% since 2000.14 The United States also imported a total of 2,820 million barrels13 of crude oil in 2013 from all countries. The total volume of produced and imported crude oil to the United States for 2013, the most recent year for which complete data are available, was thus 5,540 million barrels. Of these, 3,190 million barrels14 (58%) were delivered to refineries by pipeline. This amount includes both domestic crude (2,200 million barrels) and imported crude (992 million barrels).14 A summary of products transported in the U.S. pipeline system is presented in Table 1-1. Taken in broad strokes, the majority of the crude oil transported in the U.S. pipeline system in 2013 was conventional light and medium crude (~71%). With the recently increased production of light crude oil in the U.S., it is expected that light and medium crudes will remain dominant in the U.S. pipeline system.
In the United States, production of heavy crude oil has been roughly constant even as production of light crude oil production has, in recent years, grown rapidly.15 The principal domestic sources of heavy crude oil are in California, which produced 199 million barrels in 2013,16 most of that being transported by pipeline within the state.17 Because heated
TABLE 1-1 Types and Quantities of Crude Oil in the U.S. Pipeline System in 2013
|Type of Crude Oil||Volume in 2013 (million barrels)||% by volume in pipeline system|
|Undiluted Conventional Heavya||199||6%|
|Diluted Conventional Heavyb||273||9%|
|Conventional Medium and Light||2,278c||71%|
aDomestic production of conventional heavy crude oil, API < 27°.
bImported conventional heavy crude oil, API < 25°.
cConventional medium and light crude oil = Reported Total – (Diluted Bitumen + Diluted and Undiluted Conventional Heavy + Synthetic Crude).
SOURCES: National Energy Board and U.S. Energy Information Administration15, 19
pipelines are used, the heavy crude oils in California do not require blending with lighter products and are hence termed “undiluted conventional heavy” crude oil. Most of the other heavy crude oil that is transported by pipeline in the United States is from Canada. These heavy crude oils are diluted with lighter hydrocarbons and, hence, are referred to as “diluted conventional heavy” crude oil. Some imported heavy crude oil also comes from Mexico and Venezuela but those products arrive by tanker18 and are not typically transported by U.S. transmission pipelines.
The remaining categories of crude oil transported via pipeline are diluted bitumen and synthetic crude. In 2013, the National Energy Board (NEB) of Canada reported an export of 250 million barrels of diluted bitumen to the United States.20 The NEB has defined diluted bitumen as bitumen blended with light hydrocarbons and/or synthetic crude oil. Although there has been an increase in rail transportation of diluted bitumen, petroleum products from Canada, including diluted bitumen, are transported mainly by pipeline. By this analysis, diluted bitumen made up 8% of the crude oil carried in the U.S. pipeline system in 2013.20 The volume of diluted bitumen imported from Canada increased by ~20% in 2014. The Canadian diluted bitumen transported in transmission pipelines to the U.S. typically contains 50-70% bitumen by volume with lighter hydrocarbons accounting for the remainder.2,5b The quantity of diluents added is typically the minimum needed to meet pipeline specifications. The most common specifications for pipeline inputs are a maximum density of 0.94 grams per cubic centimeter (g/cm3) and a maximum viscosity of 350 centistokes (cSt).2,6 Bitumen blended with synthetic crude usually has a mixture of about 50% bitumen and 50% synthetic crude,5b whereas bitumen blended with naphtha-based oils derived from conventional crudes or from condensates derived from natural gas typically contains a mixture of about 70% bitumen and 30% light oils.2 Bitumen blends also vary seasonally in order to meet specifications for density and viscosity at the temperature of the pipeline.
Synthetic crude oil can be upgraded bitumen, upgraded heavy crude oil, or a mixture of those products, and makes up 6% of the total oil being transported by pipeline. “Upgrading” refers to inefficient, but cost-effective, refining procedures implemented at or near the site of production rather than after transport to a refinery. The total volumes of Canadian crudes imported to the U.S. by pipeline are presented in Table 1-2.
The statement of task seeks a comparison between diluted bitumen and “crude oils commonly transported in U.S. transmission pipelines.” A definition of commonly transported crudes is thus required. Figure 1-2 graphically depicts the volume percentages of types of crude oil transported by the U.S. pipeline system in 2013 and includes both imported and domestic oil. It shows that light and medium crude oils are the
TABLE 1-2 Volumes of Canadian Crudes Imported to the U.S. by Pipeline in 2013
|Type of Crude Oil||Volume (million barrels)|
|Conventional Diluted Heavyb||273|
|Conventional Medium and Light||206|
aBitumen blended with light hydrocarbons and/or synthetic crude oil.
bAPI gravity < 25°.
cUpgraded bitumen or upgraded heavy crude oil of any API gravity.
SOURCE: National Energy Board19
predominant crude oil products being transported in the U.S. transmission pipeline system and account for nearly three-quarters of the crude oil transported. Further, a significant fraction of the transport of heavy crude oils occurs in a single state (California), whereas other crude oils are transported throughout the contiguous United States. This is the basis for identifying light and medium crudes as commonly transported and indicating that a comparison between diluted bitumen and these crude classes provides a meaningful basis for addressing the statement of task. Accordingly, for the purposes of this report, commonly transported crudes are defined as conventional light and medium crude oils (Figure 1-2).
Key terms used to describe the types of crude oils used throughout this report are highlighted in Figure 1-3.
FIGURE 1-2 Percentages of crude oil types by volume in the U.S. pipeline system in 2013. See Table 1-1 for details.
FIGURE 1-3 Key terms used in this report.
Chapter 2 discusses the chemical and physical properties of crude oils that are relevant to environmental impact. Properties discussed in detail include density, viscosity, flash point, and adhesion. The effects of weathering on these properties are also highlighted and presented in a series of tables which are organized to compare light, medium, and heavy crude oils with diluted bitumen. The chapter concludes by identifying key differences between the properties of those products.
Chapter 3 examines the environmental transport, fate, and effects of spills of crude oils with a focus on properties unique to diluted bitumen before and after the diluent has been lost to volatilization. It also reviews relevant crude oil spills and considers potential spills in a variety of environmental settings including land, groundwater, inland waters, and coastal zones.
Chapter 4 describes the current planning and implementation of response to spills of crude oil. Each spill is unique and its characteristics depend on the chemical and physical properties of the oil and on the environment in which the spill has occurred. Predictions of the behavior of spilled oil and of its effects on health and safety are described in this
chapter and are pertinent to how a spill response will be implemented and what type of tools and equipment will be employed. The chapter reviews general response tactics and techniques for floating oils as well as tactics for detection, containment, and recovery of spills that have a higher tendency to submerge. Considering the distinctions between light and medium crudes compared to that of diluted bitumen described in Chapters 2 and 3, a descriptive table about recovery techniques for diluted bitumen spills concludes the chapter.
Chapter 5 synthesizes the information presented in the previous chapters. The differences between commonly transported crude oils and diluted bitumen are presented in three separate tables organized in terms of environmental transport, fate, effects, and spill response describing the relevant properties, potential outcomes, and levels of concern.
Chapter 6 focuses on the adequacy of current regulations governing spill response plans, preparedness, and cleanup. The chapter provides an overview of the federal spill planning and response framework for crude oil spills. Weaknesses of the current pipeline spill response planning and response framework for addressing spills of diluted bitumen are discussed.
Chapter 7 presents specific recommendations to stakeholders involved in spill response based on the committee’s analysis and assessment of the statement of task. While the focus of these recommendations is on how to increase the effectiveness of spill response planning and response for spills of diluted bitumen, the committee’s recommendations are relevant to other oils that share physical and chemical properties with diluted bitumen (i.e., heavy oils), although non-bitumen heavy oils are beyond the scope of this report.