The high intensity of hydraulic fracturing in unconventional reservoir has resulted in dramatic increase in water consumption. The reuse of produced water has been driven by both the environmental and economic benefits. The performance of conventional anionic friction reducers is usually affected by the total dissolved solid (TDS) in the water source. We present here a cationic friction reducer which is fully compatible with most of produced water based on results from the lab and field.
A cationic friction reducer was studied in the lab in synthetic brines and produced water from different Basins with TDS up to 275K. Friction reduction was measured at various concentrations of monovalent, divalent and trivalent cations in the brine. The impact of SO42- was also studied as a representative anion. Several field produced water with different level of TDS were also tested to prove the full compatibility. The additional benefit of using this cationic friction reducer is to control the clay swelling demonstrated by CST result. In the field, the cationic friction reducer was successfully applied in the slickwater jobs in North America using 100% produced water, resulting in high pumping rate with low wellhead pressure.
The cationic friction reducer shows excellent friction reduction even in very high TDS. It also exhibits good tolerance to all the cations and anions, most of which usually are problematic for anionic friction reducers. For the jobs performed, the treating pressures were well below the limit at designed pumping rates, and all proppants were placed as planned. The cost saving was significant by using produced water instead of fresh water. The results from the lab and field demonstrate that this cationic friction reducer is a good candidate for wells to be completed with 100% or diluted produced water.
This paper presents a solution to the wells that require or prefer to use produced water in their slickwater jobs. The field data shows that it saves horsepower during operation due to the high friction reduction in produced waters. It also lowers the cost related to produced water disposal and fresh water transportation.