A Comprehensive Life Cycle Assessment of Hydraulic Fracturing

Abstract

Abstract The oil and gas industry has been taking steps to achieve sustainable growth. Most E&P companies have declared their commitment to a carbon-neutral future. The first step in realizing a carbon-neutral future is to identify high-intensity operations such as unconventional hydraulic fracturing and reduce their 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 drastically reduce those emissions. The main purpose of this work 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 employed 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. As expected, the fuel consumption of fracturing pumps was the top contributor with more than 30% of overall emissions. Flaring for cleanup came second with 26% contribution in our base case. While the emissions of the fracturing fleets are often very visible due to their large footprint and duration, surprisingly, the emissions of nonroutine flaring are just as impactful. In fact, nonroutine flaring could have much higher impact depending on how fast the cleanup process could take place, which may not be easy to predict. We observed that using natural gas in internal combustion engines reduced the 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 to be 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. 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. 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.