As shale fracturing operations continue to increase, so do the required volumes of relatively fresh water - which in some areas is limited in availability for fracturing. Exacerbating the issue, thee water that is produced backk after fracturing typically contains large amounts of total dissolved solids (TDS), including sodium, calcium, magnesium, barium and oother salts. Storing and disposing of this water is becoming very expensive, and operators increasingly seek options for recycling and reusing this water. An ideal solution would be to reuse it in subsequent fracturing, but conventional fracturing fluid systems require fairly low TDS to achieve reliably stable rheology, so produced water typically requires extensive treatment before it can be reused for fracturing. A new polymer system has been designed to viscosify produced waters a minimal filtration to eliminate large solid particulates. In addition to achieving stable viscosity despite the dissolved solids in the water, the system simplifies operations, requiring only a gellant, surfactant and breaker added on the fly to the water. No buffer, crosslinker or other additives are necessary. The unique polymer system uses a specialized surfactant to create an association with the produced water and generate viscosity. The resulting fluid is elastic and has excellent proppant transport characteristics. The system can be broken efficiently to achieve good regain conductivity. This paper will present the chemistry and results of complete laaboratory testing to evaluate the fluid for fracturing operations. Testing will include demonstrations of fluid properties with typical produced water samples from the Bakken and Marcellus shales.
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