中国非常规天然气开发对水资源的影响机理、作用程度与管理应对研究

The large-scale development of unconventional natural gas (UNG) will greatly improve China's energy structure, and reduce the emissions of greenhouse gases and other pollutant gases. Water issues are the biggest environmental challenges for this development. First, this project will analyze the influence mechanism of UNG's development on water resources from perspectives of life cycle of gas wells and water supply chain. Second, by using the process-based life cycle assessment model and analyzing the estimated ultimate recovery of gas wells, the project will provide a quantitative analysis for the impacts of UNG's development on water resources from both spatial and temporal dimensions under uncertainty. The temporal-spatial characteristics and laws of these impacts will be then identified based on the analyzed results. Third, by considering the regional water availability, the UNG's development areas will be divided into two types, i.e., water-rich and water-scarce areas. Two mixed integer linear programming models will be then proposed for these two types of areas and be then used to analyze the management optimization strategies of water resources in UNG's development under uncertainty. Finally, different water regulatory policies will be designed based on the requirements of "the Most Stringent Water Resources Management System" and "Action Plan for Prevention and Control of Water Pollution". The impacts of these designed policies on the water resource management in UNG's development will be then analyzed by applying mixed-integer bi-level programming models under uncertainty. Thereafter, the most suitable strategies will be identified by using the multi-criteria decision analysis and the corresponding policies behind these strategies will be selected and recommended to the policy makers to deal with the water resources challenges.

非常规天然气的规模开发对改善中国能源结构、降低温室气体和污染气体排放等具有重要作用，而水资源是影响其规模开发的最大环境挑战。本课题首先从气井生命周期和水供应链两个视角出发，对中国非常规天然气开发的水资源影响机理进行全面剖析；然后，利用不确定过程生命周期评估模型，结合对气井最终可采储量的计算，从空间和时间两个维度对中国非常规天然气开发的水资源影响程度进行研究，并分析和揭示影响的时空特征与规律；再次，考虑区域水资源状况，分别针对富水区和贫水区两类区域构建相应的不确定混合整数线性规划模型，研究缺乏水资源管制政策下的管理优化策略；最后，结合最严格水资源管理制度和水污染防治行动计划，设计多种水资源管制政策，构建并采用不确定混合整数双层规划模型评价不同政策对水资源管理的影响效果，并运用多准则决策方法从政策实施效果与实施成本等多方面对政策进行排序选择，进而为相关职能部门制定水资源管制政策提供依据。

规模开发非常规天然气是支撑我国能源转型的重要战略举措之一，而有效解决非常规天然气开发的水资源挑战则是实现规模开发非常规天然气的必然要求。本课题基于中国本土非常规天然气开发实践，首先对非常规天然气开发对水资源的影响源及影响路径进行识别与分析；然后考虑不确定性，采用基于过程与投入产出的混合生命周期清单模型、水稀缺足迹（WSF）模型，量化评估非常规天然气开发对水资源的影响程度；之后，采用非常规天然气产量预测模型对其产量进行预测以估算开发非常规天然气的耗水量，在此基础上，构建区间两阶段随机规划、区间两阶段鲁棒优化及双层规划模型，进行非常规天然气开发的水资源分类管理优化及废水资源管理研究；最后，根据当前的“双碳”目标及油气行业高质量发展要求，设计非常规天然气水资源管制政策。主要结论为：1）非常规天然气开发对水资源的影响主要表现在水消耗和水污染两方面。时间、空间、研究边界、单井产量是影响水消耗结果的主要原因；套管泄漏、压裂储层裂缝泄漏、钻井现场处理泄漏等是水污染的主要路径。2）中国页岩气单井水资源消耗总量均值为78981m3/口；对应的水资源消耗强度均值为598.34m3/106m3。3）中国的页岩气开发活动会造成较大的用水压力，31个省份（除港澳台）中有13省的WSF值高于全国平均水平，而其他18省是否适合开发还要考虑省内页岩气资源规模、开发速度等因素。4）水资源管理中，在富水地区，决策者在缺水惩罚风险与系统利益间做出合理决策，以达到预期经济目标；而在贫水地区，决策者对待缺水风险的态度使其更倾向于系统收益降低、但能降低系统风险的保守策略。5）废水管理中，每一个钻井点都存在一个主要的产出废水分配和回用方案，产出废水不确定性的合理容忍度能提高全局满意度，利于获得更佳的优化结果。6）非常规天然气开发除自身经济效益外，还可能对整个区域经济发展和劳动力增长产生正向作用，但若考虑扩大非常规天然气生产，还需考虑环境外部性所引起的非货币成本变化。