Characterization of greenhouse gas impacts of unconventional oil and natural gas resources : analysis and field study

As the need for addressing the impacts of climate change has become more urgent, the primary focus in the scientific and engineering disciplines has been on reducing the combustion of fossil fuels through clean energy technology development. Simultaneously, there has been rapid development of unconventional fossil fuels such as tight oil and oil sands, especially in the United States and Canada. The development of these resources raises considerable obstacles to the challenge of reducing emissions. As nations realize the need for climate action and begin to transition a low-carbon energy sources, there is considerable inertia in the legacy fossil-fuel-reliant energy infrastructure. In the near-to medium-term a climate-conscious approach is needed to reduce emissions from existing infrastructure. Toward this end, this work investigates the greenhouse gas impacts of unconventional fossil fuel production. We first investigate the Alberta oil sands where we examine the historical trends in life-cycle greenhouse gas intensity of production utilizing industrial data. We show that the emissions intensity for oil sands production decreased from being close to two times greater than a modern conventional crude oil to roughly twenty percent greater. From this initial work, we utilized this operator-provided data to develop a life-cycle energy intensity model for the four most common fuel pathways in modern oil sands production. This model is both more comprehensive and more robust than prior work on oil sands emissions intensity, largely due to innovations we make in leveraging government-reported data to estimate emissions. We show that the energy intensity of oil sands production ranges from 0.08 to 0.41 GJ fuel consumed/GJ oil produced, varying by pathway. This work was integrated into the US Federal Greenhouse Gases, Regulated Emissions, and Energy use in Transportation Model (GREET) developed by Argonne National Laboratory. Next, we examine vented and fugitive emissions of hydrocarbon gas from production facilities in the Bakken oil field of North Dakota. These emissions, due to the high global warming potential (GWP) of methane (CH¬4) -- the primary component of produced gas -- are a large source of uncertainty for quantifying the greenhouse gas intensity of these resources. We conducted two studies which utilize Optical Gas Imaging (OGI) to evaluate the persistence of hydrocarbon emissions over time: 1) a helicopter survey which follows up on a previous study and examines the year-to-year trends in emissions-emitting sites, and 2) a ground-based survey where > 100 sites were visited regularly over the course of a year. Both of these studies demonstrate very high rates of persistence of emitting (as well as non-emitting) sites over the course of the study time-frame. These results strongly suggest that emissions are not random or intermittent, but instead due to long-term operational or design problems in the production, gathering, or transportation infrastructure.

Keywords: Energy Resources Engineering.
Advisor: Brandt Adam (Adam R.) 
Jackson Rob
Lobell David