The exploration and exploitation of shale gas resources has been seen as a game changer in recent years which has affected the world natural gas industry and gas market significantly. Furthermore, as the relatively cleanest fossil energy, development of shale gas resources is expected to play an important role in the world’s projected transition towards a low-carbon energy future. In this case, the large-scale extraction of shale gas resources could be inevitable in future. However, extracting shale gas resources is not an entirely environmental benign issue. Numerous studies have shown that shale gas development may have some serious environmental impacts, for example, methane leakage and huge water consumption. Of these, water-related issues are a fundamental and longer lasting obstacle. Better water resource management has been seen as one of the most effective measures for dealing with water-related issues.
This paper focuses on the management of wastewater allocation and reuse in shale gas development. Uncertainties in the process of wastewater allocation and reuse could affect the final optimization results considerably, therefore, this paper first gives a detailed description and analysis of the process of wastewater treatment and reuse and related uncertain factors. Secondly, a bi-level programming model with uncertainty is established for wastewater management for shale gas development, where economic and environmental benefits are upper-level and lower-level objectives respectively, fuzzy and interval programming is used to deal with uncertainties from the amount of produced wastewater and others in transportation, treatment, and reuse of produced wastewater. After the model is established, algorithms based on satisfaction and interaction are used for solving the model. Finally, the established model is used in a case study to show its effectiveness.
The results show that one main plan of wastewater allocation and reuse always exists for each drilling point, and this plan is mainly affected by economic factors, capacity of wastewater treatment facilities as well as the relative position of the upper and lower objective functions. Besides, the consideration of those uncertainties does make the result more objective and closer to reality. In addition, tolerance of the uncertainty in the amount of produced wastewater can improve the overall degree of satisfaction, which is good for providing the optimal results. Finally, a comparison of results from the established bi-level programming model and those from two traditional single objective programming models shows that the proposed model in this paper could achieve a trade-off between economic and environmental benefits, and this trade-off is more in line with reality
