Optimal Water Management under Uncertainty for Shale Gas Production

This paper presents a mathematical programing formulation for synthesizing water networks associated with shale gas hydraulic fracturing operations while accounting for the system uncertainty. The proposed formulation yields strategic planning that minimizes the cost considering water requirements as well as equipment capacities for treatment technologies, storage units, and disposals. The key uncertainties pertain to the water usage for fracturing and the time-based return of flowback water. The objective function is aimed at the minimization of the total annual cost, which accounts for the operating and capital costs associated with the water network. The developed model addresses the scheduling problem associated with shale gas production, which provides as output the completion phases for all the projected wells. This information is used in estimating the periods with water requirements and where flowback water can be collected. The proposed methodology includes an analysis of the optimal equipment size. An illustrative example is presented to show the capabilities of the proposed methodology.