Water scarcity assessment based on estimated ultimate energy recovery and water footprint framework during shale gas production in the Changning play

摘要

Shale gas extraction has attracted great attention, especially in China, following its energy transition toward decarbonization, while the fast-expanding shale gas industry faces serious challenges related to water scarcity and water contamination. Quantitative investigations of the impacts of shale gas production on water scarcity and water contamination contribute to public awareness that shale gas production will worsen the water resource shortage. This paper presents a comprehensive water footprint (WF) assessment to improve understanding of the water sustainability and availability in shale gas industry. A detailed process water footprint model was used to quantify precisely the potential water consumption and environmental impacts. The full water use chain in the shale gas industry was examined, from the water used for well drilling and equipment maintenance, to the injection of hydraulic fracturing fluids and the disposal of the produced water. The results indicate that the historical water consumption ranged from 633.23 m(3)/segment to 2,292.90 m(3)/segment, totaling nearly 4.54 x 10(6) m(3) for 120 wells. The projections of the estimated total WF for the constructed production period 2018-2020 and stable production period 2021-2030 were 3.30 x 10(7) m(3)/year and 5.21 x 10(7) m(3)/year in the Changning play, accounting for 10.12% and 15.98% of the average annual runoff of the Changning River, respectively, and 3.19 x 10(8) m(3)/year and 6.38 x 10(8) m(3)/year in all of the plays in China, accounting for 0.25% and 0.50% of the total national industrial water consumption in China in 2017 (1.28 x 10(11) m(3)), respectively. The grey WF was the main contributor, accounting for 94.50% to the total WF, suggesting that water quality issues should be highly emphasized and that this footprint has a significant impact on the pollution of the water bodies near shale gas sites. These findings provide a valuable insight in understanding water consumption process in shale gas industry that can be employed to develop water resource and wastewater treatment management strategies and indicate that water resource contamination will restrict shale gas development and different effective alternative forms of management strategies, laws or regulations regarding water resources should be implemented to alleviate water resource and environmental burdens. (C) 2019 Elsevier Ltd. All rights reserved.