| Currently,the global community is actively seeking solutions to the increasingly severe challenge of climate change.China has started an accelerated period of transition from a high carbon energy system to a low carbon energy system with the proposal of its"dual carbon"target.Natural gas,a comparatively clean energy source,has assumed a challenging role during this transitional period.There is always a shortage of conventional natural gas in China.Against this background,shale gas,which has the biggest estimated recoverable resources in the world,has stood at the apex of China’s energy transformation stage.As an unconventional natural gas,shale gas development is dependent on hydraulic fracturing technology.Owing to the high-water consumption features of this technology,large-scale shale gas development will necessitate the consumption of vast quantities of water resources.Since China is a typical country with limited water resources,vigorously expanding shale gas resources may pose a severe danger to China’s water use issues,and water resources may become a crucial factor limiting China’s large-scale shale gas development.The correct method to face the situation is to actively seek solutions.Therefore,the purpose of this thesis is to carry out corresponding water resource management optimization work for shale gas development in China under uncertainties,and to design water resource regulation policies based on this work to provide a decision-making basis for formulating national water resource regulation policies for the shale gas industry.Based on the practice of shale gas development in China,this study takes the water resource issues in shale gas development in China as the research object.First,it has a thorough comprehension of the effect of shale gas development on water resources and its mechanism;Then examine the impact of shale gas development on water resources from the total volume and intensity of water consumption under uncertainties;On the basis of intensity and the remaining available water from various provinces,cities,and autonomous regions in China(excluding Hong Kong,Macau,and Taiwan),each region is divided into two categories:water sufficient areas and water scarcity areas,in order to establish different water resource management optimization schemes under uncertainties;In the absence of current water resource regulation policies related to shale gas development,an optimization model for the management of water resource supply systems in water sufficient areas that only considers the maximization of system benefits is developed,while for water scarcity areas,an optimization model for the collaborative management of shale gas development systems and water resource supply systems in water scarcity areas that prioritizes the risk of water scarcity and water quality degradation is developed.A result of management optimization that maximizes the impact of shale gas development on water resources is attained.Based on this result,three different types of water resource control plans(with two intensities for each type)are established for shale gas development in China.On the basis of the improvement effects brought about by the execution of the policies,the created policies are then ranked and chosen using a method of multi-criteria decision analysis.In addition,interval values are used to represent the results due to the consideration of numerous uncertainties in the shale gas development process.The evaluation results of this thesis show that:(1)The net water consumption of a single well for shale gas development is about 8500 to 106700 m~3/well,with the net direct water consumption of a single well being approximately 6400 to 32600 m~3/well and the net indirect water consumption of a single well being approximately 32100 to 74100m~3/well;(2)During the shale gas development process,the total output of wastewater is roughly 6600 to 29800 m~3/well.After approximately 4200 to 19300 m~3 wastewater are recycled,the remaining wastewater treatment capacity is approximately 2400 to 10400m~3;(3)Based on the consideration of the estimate ultimate recoverable reserves of shale gas wells(estimated results in this thesis range from 110.6 Mm~3 to 286.6 Mm~3),the water resource consumption intensity results for shale gas development are determined.Each million cubic meters of shale gas production consumes around 211 to 584 m~3of water resources,with direct water consumption ranging between 35 and 179 m~3 and indirect water consumption ranging between 176 and 405 m~3.At the same time,the total amount of wastewater generated per million cubic meters of shale gas production is about 36 to163 m~3;(4)Based on the results of the water scarcity footprint of shale gas development obtained from the consumption intensity of water resources for shale gas development,China is divided into two categories:water sufficient areas and water scarcity areas.The water sufficient areas are concentrated in the central provinces of China,while the water scarcity areas are concentrated in the North China Plain and Xinjiang Uygur Autonomous Region;(5)According to the classification criteria for water resource enrichment in shale gas development,Hubei Province and Xinjiang Uygur Autonomous Region are selected as water resource management optimization cases for shale gas development in water sufficient areas and water scarcity areas,respectively,to obtain their optimal water allocation plans for shale gas development without water resource regulation policies;(6)Under the six different types and intensity policies designed,the water resource improvement effects of sufficient and scarcity water areas after the implementation of the policies are compared and analyzed compared with those without policies.According to the policy ranking results,the high intensity policy with dual management of total quantity and efficiency has the greatest effect on improvement.But,if the government agency needs more programs,it can select a high intensity quantity policy or a high intensity efficiency policy,even a low intensity policy combined quantity and efficiency in water sufficient regions.In water scarcity areas regions,only high intensity quantity regulation policy can be chosen. |
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