Optimal Pretreatment System of Flowback Water from Shale Gas Production

Abstract

Shale gas has emerged as a potential resource to transform the global energy market. Nevertheless, gas extraction from tight shale formations is only possible after horizontal drilling and hydraulic fracturing, which generally demand large amounts of water. Part of the ejected fracturing fluid returns to the surface as flowback water, containing a variety of pollutants. For this reason, water reuse and water recycling technologies have received further interest for enhancing overall shale gas process efficiency and sustainability. Water pretreatment systems (WPSs) can play an important role for achieving this goal. This paper introduces a new optimization model for WPS simultaneous synthesis, especially developed for flowback water from shale gas production. A multistage superstructure is proposed for the optimal WPS design, including several water pretreatment alternatives. The mathematical model is formulated via generalized disjunctive programming (GDP) and solved by re-formulation as a mixed-integer nonlinear programming (MINLP) problem, to minimize the total annualized cost. Hence, the superstructure allows identifying the optimal pretreatment sequence with minimum cost, according to inlet water composition and wastewater-desired destination (i.e., water reuse as fracking fluid or recycling). Three case studies are performed to illustrate the applicability of the proposed approach under specific composition constraints. Thus, four distinct flowback water compositions are evaluated for the different target conditions. The results highlight the ability of the developed model for the cost-effective WPS synthesis, by reaching the required water compositions for each specified destination.

Environmental and Economic Water Management in Shale Gas Extraction

“…The optimal pretreatment superstructure considered was obtained from the work by Carrero-Parreño et al [49], where the optimal pretreatment arrangement is obtained depending on the input water properties and the desired destination of the wastewater. Our case study corresponds to the optimal pre-treatment solution for a desalination treatment by membrane or thermal technologies in order to remove TDS content.…”

“…v.3.4 and ReCiPe 2008 characterization factors. For the pre-treatment, we use the optimal configuration presented by Carrero-Parreño et al [49] and the impact factors obtained in previous sections. For the on-site desalination, we use the MEE-MVR configuration that has proved to be the best alternative from both the economic and environmental points of view.…”

Process optimization for zero-liquid discharge desalination of shale gas flowback water under uncertainty

“…Further information about efficient pre-treatment processes applied to shale gas flowback water is presented in Carrero-Parreño et al (2017). In this case, we assume that shale gas flowback water remains with elevated concentration of salts after its pre-treatment.…”

“…In any case, shale gas wastewater demands specific pre-treatment-that comprises filtration, physical and chemical precipitation, flotation and sedimentation-and effective desalination to allow its reuse or safe disposal (Carrero-Parreño et al, 2017). In addition to chemical additives and other pollutants (e.g., organic matter, particulates, greases, and radioactive elements, to name a few) (Vengosh et al, 2013), hypersaline concentrations in shale gas flowback water can be hazardous to human health and the environment (Vengosh et al, 2014).…”

Development, Characterization, and Applications of Capsaicin Composite Nanofiltration Membranes

“…Drinking water treatment processes have developed to the point of requiring more advanced pretreatment processes [2]. Nanofiltration (NF) might function as a pretreatment for reverse osmosis desalination [3], as it can remove hardness, specific heavy metals, and reduce the salt content of feed water [4].…”