Oxidation

Fact Sheet - Oxidation

   
 
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One of the newer technologies being discussed for treating produced water and flowback water is referred to as advanced oxidation. Ecosphere Technologies, Inc, has commercialized an advanced oxidation process (Ozonix®) that has been used by the oil and gas industry to treat contaminated water. The Ozonix® technology combines ozone generation, cavitation, and electro-chemical decomposition in a reaction vessel. The process reduces the use of biocides, scale inhibitors, and friction reducers when the treated water is reused for frac fluid. During 2009-2010, the Ozonix® technology was used on over 100 wells to destroy bacteria and inhibit scale formation.

Ecosphere’s EcosFrac™ units are capable of processing up to 120 bbl/min during fraccing operations. The Ozonix® technology produces a clean brine that can be reused as a chemical-free fracturing fluid. If a fresh water product is desired for soil farming purposes, the clean brine can be further treated by reverse osmosis.

How It Works
The following description is based on the Ecosphere website (undated) and Horn (2009).

Super-saturated, ozonated water is rapidly mixed with flowback or produced water using hydrodynamic cavitation through a liquid sparger. Dual-frequency ultrasonic transducers initiate the dissolved gas flotation of oils and suspended solids and the conversion of ozone to hydroxyl radicals. In the presence of an ultrasonic cavitation field, ozone decomposes into hydroxyl radicals and oxygen gas. The hydroxyl radicals quickly oxidize organic compounds. Very small cavitation bubbles implode, providing a liquid-gas interface in a reaction that instantaneously heats the liquid-gas to approximately 900 degrees F, which in turn immediately oxidizes the organic compounds.

Example
Horn (2009) describes how the Ozonix® process was used to treat flowback water from the Woodford Shale in Oklahoma during a 2008 pilot project. A mobile unit processed flowback from two horizontal shale gas wells for 12-14 hours a day for two weeks. The flow rate was 100 bbl/hr. Since those early tests, the processing rate has been increased to 120 bbl/min, and the process has been refined.

Scale Reduction Performance Data
Ecosphere arranged for a third-party testing lab to conduct several tests to compare the scaling rate of untreated water to water treated by the Ozonix® process. Test A was conducted on produced fluid having approximately 150,000 ppm TDS and treated at 200 bbl/hr. Test B was completed on flowback fluid having approximately 10,000 ppm TDS and treated at 140 bbl/hr. In both tests, the water treated by Ozonix® showed little or no scaling during the test period while the untreated water show a marked rise in scaling after only 20 minutes.

References 
Ecosphere Website, undated, http://www.EcosphereTech.com/. For details on how the process works see http://www.EcosphereTech.com/technology/ozonix/how-it-works. Accessed October 5, 2010.

Horn, A., 2009, “Breakthrough Mobile Water Treatment Converts 75% of Fracturing Flowback Fluid to Fresh Water and Lowers CO2 Emissions,” SPE 121104, presented at the SPE Americas E&P Environmental and Safety Conference, San Antonio, TX, March 23-25.

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