Impacts of hydraulic fracturing on surface and groundwater water resources: A case study from Louisiana, USA.

Abstract

Background: Unconventional oil and gas reservoirs, frequently referred to as shale plays , have been gaining more attention in recent years. Hydraulic fracturing is performed to extract fossil fuels from unconventional reservoirs. Besides possible environmental implications, a better understanding of the potential stress that fracking may cause to water resources at the local or regional scale is still needed. The goal of this study is to assess the impact of current and projected future water demands for fracking on water resources in two main shale plays in Louisiana, USA. Methods: The analysis is performed in Louisiana’s two main shale plays, the Haynesville Shale and the Tuscaloosa Marine Shale, using the Water Supply Stress Index (WaSSI) framework. WaSSI is used to evaluate the stress at a fine watershed scale (HUC12) for annual-average conditions. The study analyzes different scenarios of historical and two future projected fracking conditions that simulate different extraction rates. In each fracking scenario, stresses on both surface and groundwater are evaluated separately. The study is based on a multitude of water supply and withdrawals datasets assembled and disaggregated to the watershed scale. Results: Under existing conditions, the impact of fracking water demands on surface water resources is within the low stress category in most watersheds in both shale plays. This impact remains low under more aggressive future fracking scenarios. In contrast, groundwater resources appear to be highly vulnerable under both the historical and projected fracking scenarios, especially in the Haynesville Shale where 20 out of the 94 watersheds become medium or highly stressed. If groundwater resources remained as a main source for fracking water, the number of stressed watersheds increased to 39 and 86 under the two projected future fracking scenarios. The least exploited Tuscaloosa Marine Shale remains mostly under low stress, except in the most aggressive future fracking scenario. Conclusions: Surface water resources in Louisiana’s shale plays seem abundant enough for fracking activities to rely on this source instead of groundwater whenever possible. Groundwater resources in Louisiana are clearly vulnerable to fracking activities, especially for the Haynesville shale play, under current and future projected fracking conditions.