Abstract:
Hydraulic fracturing, also referred to as Hydrofracturing, has enabled the economical recovery of gas and oil from the unconventional reservoirs, such as Marcellus Shale and Niobrara. Produced water refers to the water that returns to the surface, typically 10 to 30% of the original injected amount. The produced water is composed of the original components in the fracturing fluid as well as any materials that may have entered it through its contact with the surrounding geology and groundwater, which generally results in an aqueous mixture rich in organic and inorganic substances. Produced water management has been discussed and reported by government agencies and industrial partners. The soluble organics often result in problematic re-injection of the produced water (for pressure control), such as unpredictable pore plugging of the fractures, when used to make up part of the hydraulic fracturing fluid. However, to remove the dissolved organic compounds (DOC) requires advanced water treatment that can be as costly as $8/barrel in Wyoming. One of the primary reasons for high costs results from fouling on commercial surface treatment facilities caused by DOC. The fouling issue is a concern because it results in decreased process efficiency and, consequently, increased operating and capital costs. Here we propose to develop hybrid membranes by depositing smart materials, such as TiO2 nanoparticles, onto commercial membranes (the central pieces of a commercial water/oil separation module) via a recently developed technique in the Li lab. Thanks to the photo-oxidative and hydrophilic properties of smart materials, the hybrid membrane allows decomposition of DOC, consequently breaking up aggregations of organic molecules before the formation of much larger particles. As such, the proposed technology prevents pore plugging when rejecting produced water as part of the hydraulic fracturing fluid, providing a cost-effective reuse in energy exploration loop and, alleviating environmental concerns of the citizens of Wyoming.
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