Characterization and comparison of flowback/produced water of fresh water to recycled water stimulated wells and the subsequent evaluation of the influence of inorganic ions on fracturing fluid viscosity
Date
2016
Authors
White, Shane A., author
Carlson, Kenneth, advisor
Catton, Kimberly, committee member
Sutton, Sally, committee member
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Abstract
As the Oil and Gas Industry begins to recycle flowback and produced waters, new challenges arise in using recycled water as a base fluid (fluid for hydrating gel) for future hydraulic fracturing operations. By understanding water qualities at all steps of the water life cycle in recycled operations, it is possible to improve treatment effectiveness and efficiency as well as make informed decisions on future fracturing fluid designs. This thesis contains two studies. The first study looks to determine water qualities, their differences and similarities, among multiple wells in the same Basin. These wells were fractured using a variety of techniques such as varied recycled to fresh water blends and fluid designs. The collection and water quality analysis of roughly 150 samples from seven wells on two different sites showed that there is little difference in water quality between wells fractured with recycled water (recycled wells) and wells fractured with fresh water (fresh wells). The study does not find noticeable differences in dissolved ionic concentrations between fresh and recycled wells. However, recycled wells located on the first site show emulsified oils in flowback. This can be observed with increased total organic carbon loadings of 12,170mg/l for day three flowback of one recycled well in comparison to 3,268mg/L for day three flowback of a fresh well. Treatment effectiveness was also correlated with emulsified oil concentrations and as their concentrations decreased, so did the coagulant dose required for optimum treatment. Spatial variation was observed between the two sites. Although the concentration of varying inorganics between the two locations was observable, temporal trends were consistent between wells. The second study provides data that can be used in decision making for future fracturing fluid design and development. By observing the effect individual ions and ion combinations have on fracturing fluid stability, operational limits were determined for two fracturing fluids employed by operators in the DJ Basin. Theoretical mechanisms of action were determined for the factors that influence fracturing fluid stability. Specific cations compete for crosslink sites on the gel polymer through shielding or by competitively complexing with active sites that the added crosslinker would normally complex with, resulting in a less stable fluid. Hydrogen bonds can sometimes form bonds at active sites and make a weak crosslink. At lower concentrations calcium and magnesium can replace these weaker crosslinks with stronger bonds, creating a more stable fluid.
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Subject
fracturing fluid rheology
oil and gas
water treatment
hydraulic fracturing
fluid design
produced water