MEMBRANE FOULING DURING MICROFILTRATION TREATMENT OF HYDRAULIC FRACUTURING FLOWBACK WATER

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Author:
Roman-White, Selina Amber
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Manish Kumar, Thesis Supervisor
  • Darrell Velegol, Honors Advisor
Keywords:
  • Fracking
  • Flowback
  • Hydraulic Fracturing
  • Microfiltration
  • Membrane Fouling
Abstract:
High Volume Hydraulic Fracturing (HVHF) is an important, yet water intensive process for recovering natural gas from shale formations. The average well stimulation uses between 1.5 and 4.5 million gallons of fracturing fluid. Water and sand compose 98% by volume of the fluid, and the remaining 2% a mixture of chemical additives. Over 960 organic chemicals have been detected in flowback water as well as impacted surface and ground water. HVHF raises many environmental concerns over water use and contamination. Current disposal methods are not sustainable, and a better method that allows recycle of the water is necessary. Microfiltration is one viable option. Though microfiltration allows for treatment of the flowback water, enabling reuse for future fracking stimulations or other beneficial reuses, there is little research on the topic. This investigation aimed to increase understanding of microfiltration as a treatment method for flowback water, determining which additives lead to fouling of the membrane and under what conditions, as well as examining the resulting water quality of the flowback. This was achieved through production and analysis of a synthetic flowback water that mimicked industry frack fluid composition as well as well-bore conditions. The results indicated that well-bore conditions are critical for polymer degradation and minimal fouling, most importantly a high reaction temperature. Well-bore conditions (80°C, 1200 psi) decreased the molecular weight of the polyacrylamide friction reducer from 15000 kDa to 120 kDa. Friction reducer was identified as the primary fouling agent, due to the large polymer size preventing flow through the membrane. Friction reducer-only flowback fluids fouled almost immediately. Breaker was shown to reduce fouling significantly, as the additive encourages the degradation of friction reducer. Lastly, surfactant was shown to prevent degradation of the polymer and cause fouling. Fluids that contained surfactant 0.15% v/v produced a friction reducer with molecular weight of 600 kDa, 5 times that of friction reducer-only flowback fluid. Flowback water was found to have a much lower total organic content (TOC) compared to the raw, unreacted fluid. These results have important implications for industry and the environment. The findings above suggest possible pre-treatment strategies to prevent membrane fouling during microfiltration of the flowback water. Filtering and reusing the water would greatly reduce the freshwater use in industry, decreasing the environmental impact of HVHF. Microfiltration is a beneficial practice for both industry and the environment, providing a more sustainable option for the treatment of flowback water.