(182d) Cost Modeling of Desalination Technologies for the Treatment of Shale Gas Waste Water (SGWW)

The advent of hydraulic fracturing (fracking) has revolutionized the natural gas industry by facilitating the extraction of vast amounts of otherwise inaccessible gas reserves trapped in shale formations. However, this revolution introduced a host of technical and environmental challenges. The fracking process produces large amounts of waste water (SGWW) that requires management. Traditionally, this water would be disposed of by injection in deep wells. New regulations, and an increased emphasis on environmental concerns, have prompted the industry to seek alternative means of managing SGWW, including recycle or reuse of the water. This would require treating the water to improve the quality and purity, to meet the standards required for the desired application. Adding to the complexity of the challenge, the nature of SGWW varies significantly over the lifetime of a gas well, as well as its geospatial location. In order to develop optimized treatment strategies, an understanding of the water quality, the technologies used to treat SGWW, and the relationship between the two is required.

In this work we studied current commercial processes and emerging technologies that are used for shale gas wastewater treatment, and we analyzed them based on their working principles, limitations, advantages, and drawbacks. Specifically, thermal based (e.g., mechanical vapor compression, multi-stage flash distillation, multi-effect distillation) and membrane-based (electrodialysis, nanofiltration, membrane distillation, forward osmosis, reverse osmosis) processes and their applications as part of the shale gas wastewater treatment technologies have been studied. A parametric study has been carried out to identify the factors that affect the capital and operating costs of these processes. In order to establish accurate correlations to model both capital expenditure (CAPEX) and operating expenditure (OPEX) equations, data mining activities were carried out based on open literature data (including both academic and company reports). We utilized data preparation techniques to refine the most relevant published plant data, which serves as the basis for the developed empirical correlations.

In this presentation we will discuss the result of these efforts. For each SGWW treatment technology studied in this work, a multi-parametric cost estimation equation for both CAPEX and OPEX was developed. Non-linear parameter fitting strategies were utilized to reflect the nonlinear nature of the relationship between costs and the parameters used in the equation. CAPEX correlations were developed to include capacity, total dissolved solids (TDS) concentration, and water recovery for the specific technology. OPEX correlations were modeled as a function of capacity, specific energy consumption, TDS concentration, and water recovery. The compiled data and developed cost correlations provide important tools for optimization, techno-economic and performance assessment of various treatment technologies, based on the characteristics of the water to be treated. Furthermore, horizontal falling film evaporators (FTFFE) were assessed as a base-case treatment technology, and the performance metrics for the base case were estimated and compared to the other technologies studied in this work.