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Hydraulic fracturing (HF) events consume high volumes of water over a short time. When groundwater is the source, the additional pumping by rig/frack supply wells (RFSWs) may impose costs on owners of other sector wells (OSWs) by lowering the hydraulic head. The Carrizo–Wilcox aquifer in south Texas is the main source of water for HF of the Eagle Ford Shale (EFS) Play. The objectives are to assess the impacts of groundwater pumping for HF supply on: (1) hydraulic heads in OSWs located nearby an RFSW and (2) volumetric fluxes between layers of the regional aquifer system compared to a baseline model without the effect of RFSW pumping. The study area spans the footprint of the EFS Play in Texas and extends from 2011 to 2020. The pumping schedules of 2500 RFSWs were estimated from reported pumped water volumes to supply 22,500 HF events. Median annual drawdowns in OSWs ranged from 0.2 to 6.6 m, whereas 95th percentile annual drawdowns exceeded 20 m. The magnitudes of drawdown increased from 2011 to 2020. Of the four layers that comprise the Carrizo–Wilcox aquifer, the upper Wilcox was the most intensively pumped for HF supply. During the peak HF year of 2014, the net flux to the upper Wilcox was 292 Mm3 compared to the baseline net flux for the same year of 278 Mm3—a relative gain of 14 Mm3. Pumping for HF supply has the potential to negatively impact nearby OSWs by capturing water from adjacent aquifer layers. [ABSTRACT FROM AUTHOR]

As more aquifer storage and recovery (ASR) systems are employed for management of water resources, the skillful operation of multiwell ASR systems has become very important to improve their performance. In this study, we developed MODFLOW and MT3DMS models to simulate a multiwell ASR system in a synthetic aquifer to assess effects of hydrogeological and operational factors on the performance of the multiwell ASR system. We evaluated a simplified (dual well) ASR system in comparison with complex system (three‐, four‐, five‐, and seven‐well systems). Recovery and energy efficiencies were calculated using the model simulations. Factors such as higher hydraulic conductivity and longitudinal dispersivity significantly reduced the recovery and energy efficiencies of the system. In contrast, increasing the volume of recharged water increased the recovery efficiency; however, the energy efficiency was reduced. Recovery and energy efficiencies also plummet when there is an increase in the underlying regional gradient and the designed storage duration. Operating the system multiple times can yield higher volume of potable water, but the energy efficiency may not vary significantly after the second operating cycle. Single‐well systems and multiwell systems exhibit similar responses to changes in physical factors, although operational factors have a more pronounced effect on the multiwell systems. One of the major findings was that fewer wells in a multiwell ASR system can yield higher volume of potable water and better output with respect to the electrical power being consumed. The results provide design engineers with guidelines for optimizing performance of the multiwell ASR systems. [ABSTRACT FROM AUTHOR]