| dc.description.abstract | This study evaluates the impacts of recent groundwater pumping for hydraulic fracturing (HF) on: 1) hydraulic heads; 2) gross water volumes going into and out of storage; and 3) gross water fluxes within and between the Dockum and lower Ogallala aquifers underneath the focus area in the Permian Basin, in west Texas. The focus area of the study is the properties of University Lands (UL). These impacts were first calculated for the past 9 years (2012-2020), and then forecasted for the next 30 years (2021-2050) utilizing a Groundwater Availability Model (GAM) developed by the Texas Water Development Board for the lower Ogallala and Dockum. The forecast assumes four different scenarios generated from two levels of two parameters: percent recycling of flowback water (0 and 30%) and anticipated pumping rates (low and high). Future pumping rates for HF supply will likely be influenced by global oil and gas prices and US domestic energy policy changes. The study area was divided into three regions managed by UL: Northern Midland Basin, Delaware and Central (D&C) Basins, and Southern Midland Basin. The locations of the Rig/Frack supply wells and HF oil production wells were collected from databases hosted by the Texas Water Development Board (TWDB), Texas Commission of Environmental Quality (TCEQ), FracFocus, and UL. The exact source of water supply for each HF event is unknown. Therefore, three approaches were developed to assign the water source for HF supply across known Rig/Frack supply wells within each region: 1) annual water demand for HF events was met by existing Rig/Frack supply wells screened in all underlying aquifers; 2) water demand for HF events was met by existing Rig/Frack supply wells screened in the Dockum aquifer; 3) the nearest water supply well to a HF event was assumed to supply all the water for that event. The second approach represents the official policy of UL for sourcing water from the Dockum aquifer. Water quality across the Pecos Valley, Edwards-Trinity (Plateau), and Dockum aquifers in the study area varies substantially, ranging from very fresh to saline and TDS varies from 10 to 10,000 mg/L. The simulations found that groundwater pumping for HF supply on UL properties has minor impacts on the water levels of the Dockum aquifer. The aquifers underneath UL can provide water for HF even if pumping remains high due to the large volumes of stored water within the aquifers. If pumping activity shifts to the Dockum aquifer exclusively, more water would flow downwards than upwards thereby protecting the high quality fresh water of the lower Ogallala from deteriorating. | en |
