Vulnerability indices for waterbodies impacted by theoretical hydraulic fracturing spills modeled utilizing GIS.

摘要

Hydraulic fracturing is a method used to extract oil or natural gas from unconventional sources. Within western North Dakota it is largely used to extract oil from the Bakken Formation since the low permeability of the Bakken shale makes conventional methods of oil extraction difficult. Hydraulic fracturing utilizes large volumes of frack fluid and this frack fluid is toxic to humans, animals including livestock, and vegetation including crops. Research is needed to provide a greater understanding of where frack fluid would travel if spilled, how much frack fluid could infiltrate into the soil, and how much frack fluid could impact waterbodies.;The spill pathways of frack fluid were modeled by integrating National Elevation Dataset (NED) Digital Elevation Models (DEMs) with well site locations in ArcMap 10.2. SSURGO datasets were utilized to estimate the volume of frack fluid that the soil was able to hold along the spill path. Twelve different scenarios based on spill volume and soil infiltration level were used to create vulnerability indices that were normalized between 0-1 in order to compare the vulnerability of different waterbodies and watersheds relative to the worst spill in the study area.;This study finds that spills of volumes that have occurred within North Dakota are large enough that, if unmitigated, water quality can degrade. Threatened waterbodies include both large waterbodies that are the water source for many North Dakotans such as Lake Sakakawea, and smaller waterbodies that may only be utilized by the landowner. Due to the ability of large waterbodies to dilute the impacts of spills, under certain scenarios, the most vulnerable waterbodies are small ones as they can be severely degraded by small spills. This puts individual landowners who rely on a small waterbody within their property at risk from the impacts of spills. Additionally, spill pathways can, depending on the size of the spill, extend from areas where hydraulic fracturing is allowed to areas where it is banned making it difficult for landowners to protect their property from the impacts of spills.