Effect of dissolved solids on reuse of produced water at high temperature in hydraulic fracturing jobs

Some divalent cations such as calcium and magnesium have negative effects on the prepared polymers. Magnesium is the controlling ion, and approximately 30% of flowback fluids must be treated to meet the maximum acceptable concentration criterion. While monovalent cations such as sodium and potassium were tolerable at higher concentrations and the potassium contents in almost all flowback fluids met the determined acceptable value, more than 40% of samples required treatment for high sodium ion concentrations. Although the presence of other ions such as iron shows no significant variation in fracturing fluid properties, they can affect treatment in special cases. Adjusting the concentrations of the polymer, buffer, and crosslinker can minimize the adverse effects of temperature and salts. The fluids prepared with the determined ranges of dissolved solids showed reasonable thermal stability and proppant transport characteristics. This paper introduces the practical operating range for produced water composition and defines the ions that can adversely impact borate-crosslinked fracturing fluid characteristics at different temperatures.