Water Treatment

Due to the complex nature of hydraulic fracturing flowback and produced water, disposal options and treatment options are non-traditional. The current practice of disposal by deep-well injection may not be sustainable; thus, treatment and reuse could improve the sustainability of the water cycle in hydraulic fracturing and production operations. To understand the treatability of the wastewater streams, specific water quality characteristics, including organic and inorganic constituents, need to be determined. Suitable treatment options need to be studied based on knowledge of water quality and required water quality for desired end use goals. Technologies should be tested at the pilot scale to determine effective and efficient treatment potential.

Above: water is mixed with additives to make fracturing fluid. The water returns to the surface as flowback water, mixed with salts and metals from the geologic formation.

Objective

The main objectives of the water treatment thrust are to evaluate and develop sustainable techniques for on-site treatment of frac flowback and produced water. The main tasks for this year include (1) characterization of flowback and produced water from Colorado, (2) examination and optimization of physical/chemical, biological-based, and membrane-based treatments on bench- and pilot-scale systems, and (3) evaluate the fate and transport of oil and gas wastewater constituents in subsurface and in edible and nonedible crops.

Role in Overall Project

Sustainable water treatment for reuse in the upstream O&G sector will reduce environmental stresses associated with limited local water resources and the current need to transfer water with thousands of truckloads. Results from technology development will be incorporated into a decision support tool currently developed under a US Department of Energy / Research Partnership to Secure Energy for America grant at the Colorado School of Mines and New Mexico State University (http://aqwatec.mines.edu/produced_water/tools/) to enable stakeholders to select sustainable processes for the treatment and beneficial reuse of reclaimed water from the oil and gas industry.

Above: the treatment team is comparing different methods of removing carbon and other dissolved solids from flowback water.

Recent Findings

Accurate characterization and quantification of contaminants in produced water and fracturing flowback wastewater are essential to ensure proper treatment and reuse or disposal of these wastewaters. Therefore, a collaborative inter-laboratory round-robin comparison was performed using methods applied to oil and gas development and production wastewaters. Four samples were analyzed using five different methods. The samples included raw fracturing flowback, treated fracturing flowback, raw produced water, and treated produced water. While results for inorganic constituents were consistent and satisfactory, results from quantification of organic matter and hydrocarbons from only a few participants were inconsistent and scattered. Therefore, a second phase round-robin study that focuses on organics and hydrocarbons will be conducted in the summer and fall semesters of 2016.

In the last year, this task has (1) established new relationships with operators in the field for frequent collection of frac flowback and produced water, which has allowed us to conduct long-term field studies of these O&G wastewaters; (2) analyzed and characterized flowback and produced water from the Denver-Julesburg basin, including organic compounds (volatiles and trace organic matter), inorganics, naturally occurring radioactive materials, and metals, and (3) developed methodology and performed toxicity screening assays for different hydraulically fractured wells and at various well ages.