Frac flowback water blending and treatment requirements based on spatial and temporal water quality analysis
Date
2015
Authors
Li, Wanze, author
Carlson, Kenneth H., advisor
Omur-Ozbek, Pinar, committee member
Stednick, John D., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Because of the large amount of wastewater generated with oil and gas production and the complex components of produced water, associates in the human health and environmental disciplines consider the treatment and reuse of produced water as a central issue for the petroleum industry. At present, produced water recycling is one of the best ways to reduce fresh water consumption in the hydraulic fracturing process and lessen environmental impact. This study focuses on the analysis of produced water quality and the optimization of the produced water recycling. Samples of produced water from more than two hundred horizontal wells in seven Integrated Development Plans in the Wattenberg Field were analyzed for temporal and spatial levels of total dissolved solids (TDS), sodium, chloride, calcium, and iron. Concentration of total dissolved solids, sodium, chloride and calcium were modeled to accommodate the different temporal functions in each Integrated Development Plan; the temporal logarithmic functions of each model allow prediction of produced water quality data for existing wells or new wells in certain regions. Iron concentration, however, closely correlates with geological formation, so the iron concentration of produced water must be determined spatially as an average value and maximum value in each Integrated Development Plan. A framework for optimizing produced water reuse is presented as part of this study. Typically, some volume of fracturing fluid is retained in wells; further, portions of flowback fluids might be injected into disposal wells. Produced water must be treated to meet recycled water quality requirements. In this study, coagulation/filtration, softening/clarification, and reverse osmosis (RO) were applied to treat samples effectively for suspended solids, total dissolved solids, sodium, chloride and calcium. Following treatment, the proper amount of fresh water needed to blend with the produced water must be determined. With sources of fresh water limited, the amount of water used to optimize the recycling of produced water is one of the most significant issues in the management of produced water. Calculating the quantity of fresh water necessary can be based on the quality of the fresh water, fracturing fluids and the targeted quality of the recycled water; in some cases, it might be based on the quantity of fracturing fluids and recycled water targeted. If the result based on quality is not less than the quantity based result, additional treatment will be required. Frac fluids modification could also be used in some conditions in this program, however, the cost of additives can be high, and additional treatment may be the better option. Most of recycle produced water quality with our treatment reaches requirements of fracturing fluids after blending with certain amount of fresh water. Produced water quality analysis of the horizontal wells in the Wattenberg Field and the established produced water recycling system program are supporting produced water management and the viability of produced water reuse. The Matlab produced water recycling program incorporates both internally sourced quality analysis data and external data uploaded from users. As a tool simulating produced water recycling, it can help users make good decisions to use in water management.