Globally, the extraction, transport, and refining of crude oil on average accounts for about 18% of well-to-wheels greenhouse gas emissions from fossil fuels—that is, the total emissions produced from the oilfield to burning fuel to move a car. That equates to roughly five times the CO2 emissions of Germany. But these emissions vary significantly with source and type of crude and production methods. For the highest intensity crudes, extraction-to-refining constitutes around 40% of the overall carbon footprint, about 50 grams CO2 per megajoule. This compares to only about 5%, or 4 grams of CO2 per megajoule, for the lowest intensity crudes.
This report lays technical groundwork for regulations aimed at driving down extraction-to-refining emissions. Based on a life-cycle assessment of approximately 3100 oilfields in countries that supply oil to Europe, the study develops GHG emission factors for five elements of extraction-to-refining analysis: crude oil extraction, flaring and venting, fugitive emissions, crude oil transport, and refining. Centrally, the analysis identifies the parameters that influence GHG emissions throughout the petroleum life cycle and uses them in estimating emission factors for each oil field, based on 2009 data. Those parameters range from oilfield age, gas-to-oil ratio, feedstock, and development type to transport mode and distance.
This report highlights the dramatic disparities in life-cycle greenhouse gas emissions of crudes produced from different oilfields, and points to significant reductions that could be achieved by infrastructure improvements, technology upgrades, and other measures. It provides detailed estimates of the carbon intensity of crude oil down to the level of individual fields and identifies the data needed to make those calculations.
As the report vividly confirms, the highest upstream GHG emissions are caused by natural gas flaring and the development of unconventional oil sources. Flaring, which releases the potent greenhouse gas methane as well as CO2, is primarily an infrastructure issue, related in part to lack of sufficient local demand to justify additional production facilities and pipelines. Extraction of unconventional oil, such as tar sands, requires substantial energy inputs. While in 2010 unconventional sources make up only a fraction of the EU fuel mix, any forward-looking policy must account for them. The U.S. Energy Information Administration projects that 8% of the global supply will come from unconventional oil by 2035.
Erratum: Figure 16 was originally published erroneously showing the 2020 projected volumes and intensities rather than the 2010 figures. This has been corrected.