A Comprehensive Life Cycle Assessment of Hydraulic Fracturing

Summary The oil and gas industry has been taking steps to achieve sustainable growth. Most exploration and production companies have declared their commitment to a carbon-neutral future. The first step in realizing this goal is to identify high-intensity operations, such as unconventional hydraulic fracturing, and reduce those emissions. Therefore, the primary objective of this work is to quantify the main sources of emissions in the hydraulic fracturing value chain and identify technologies that could dramatically reduce those emissions. Our first primary goal is to identify nearly all sources of emissions and the scale of their impact. Once the main emission sources are identified in the entire unconventional fracturing chain, we then focus on technologies that enable significant emission reduction. We used qualitative and quantitative analysis to assess the emissions impact of diesel engines, material transportation, and water utilization. Our observations yielded a high-level view of emission intensity across the value chain of hydraulic fracturing. Wellsite execution–related fuel consumption during pumping was the highest contributor to emissions at 36%, followed closely by the flaring for fracture cleanup at 29%. Total transportation contributed 24% to the total emissions. While the emissions of the fracturing fleets are often very visible due to their large footprint and duration, surprisingly, the nonroutine flaring and transportation are also impactful. In fact, nonroutine flaring could have a much higher impact depending on how fast the cleanup process could take place, which may not be easy to predict. It is reported that using natural gas in internal combustion engines reduces CO2 emissions. However, the methane leak from engines would offset the CO2 savings and render the benefits marginal. We also observed that the reuse of produced water is a feasible way to reduce the well stimulation footprint on water resources, which could be enabled by improved water treatment techniques at scale, advances in hydraulic fracturing fluid composition, and appropriate infrastructure. We quantified the upstream emissions (embodied carbon) of commonly used chemicals, and our calculations show that the embodied carbon of commonly used chemicals in unconventional fracturing is rather small. Our conclusions emphasize the importance of adopting ecofriendly technologies to address the challenges posed by hydraulic fracturing. They can impact up to 35% of emissions reduction. This study contributes a high-level, yet accurate, perspective on emissions of the hydraulic fracturing process. We highlight the high-emitting steps in the process and identify technology gaps that could reduce the emission footprint of the industry. This research underscores the urgency of adopting responsible practices in hydraulic fracturing for a harmonious coexistence with global sustainability objectives.