2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 11: Recycling & Environmental
| Editors: | Kongoli F, Havlik T, Pagnanelli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 410 pages |
| ISBN: | 978-1-987820-34-8 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Processing of Backflow Fluids from Hydraulic Fracturing of Gas-Bearing Shale with Recovery of Valuable Metals
Grazyna Zakrzewska-Koltuniewicz1;1INSTITUTE OF NUCLEAR CHEMISTRY AND TECHNOLOGY, Warsaw, Poland;
Type of Paper: Regular
Id Paper: 283
Topic: 7
Abstract:
Hydraulic fracturing is a well-developed technology that has been used for production of natural gas from the shale for at least 60 years. The type and composition of fluid applied for fracturing depend on the specific geologic formation, its structure and target for a wellbore. Usually, fluid contains some chemicals (hydrochloric acid, friction reducers, biocides, guar gum, emulsifiers and emulsion breakers) and proppants, e.g. suspended sand or ceramic grains, in order to keep an induced hydraulic fracture open. In back flow fluid, the components of the host rock, like heavy metals, leached during penetration of the pores by fluid are present.
If water is used as the pressurized fluid, as much as 20 % can return to the surface via the well as backflow fluid. This fluid can be treated and reused for subsequent hydraulic fracture procedures what significantly reduces the volume of fresh water consumed and the amount of wastewater generated by hydraulic fracturing. The injected fluid is managed by various methods and can be recovered to some extent; the rest is left for temporary storage. The new technologies are continually being developed to better handle wastewater and improve to reusability of backflow fluids.
In the present work, the method of treating the backflow fluids with simultaneous recovery of the valuable metals is proposed. The elaborated scheme for treatment of the fluid after hydraulic fracturing involves several stages of processing that includes oxidation of organic components, reduction of salinity and removal of dissolved matter by membrane methods, and separation of specified elements by ion exchange chromatography. Trace elements, e.g. uranium, chromium, thorium, scandium, arsenic, nickel and lanthanides are present in the fluids in various concentrations. Some of them, like uranium, are worthy to be recovered.
The treatment of the backflow fluids is necessary before reusing in the next fracturing actions or safe discharge to the environment; the separation of metals leached from the rocks during shale gas extraction not only reduces the environmental impact, but also may have an economic dimension.