Abstract
Recent studies involving the measurement of friction reducer performance with a variety of brines typical of flow back/recycled stimulation waters of the North Eastern United States have indicated a clear differentiation by specific product type. The friction reducer variances specifically studied were: product charge, charge type, charge distribution reflective of polymerization, molecular weight, inverse emulsion surfactant packages, and manipulation of the internal or external phases.
Increasing environmental regulatory pressure in geographic regions sensitive to water use, stimulation flow back discharge, and an increasing need for recycled water, the Marcellus gas play for example, have created a greater demand for higher performing additives in fluid systems used for oil/gas well fracturing. One additive that is greatly influenced by brine characteristic and water quality is the friction reducer. Increasing the ionic strength as well as multivalent cation content of the water typically limits the type of friction reducer used to obtain optimum performance. Standard anionic friction reducers do not perform well in many of these recycled waters as the friction reducer’s ultimate performance is decreased, but also the rate of inversion is retarded and the potential for formation damage is increased.
When compared to standard friction reducers, the ultimate friction reduction of the best of the series studied achieved nearly twice the friction reduction, approaching Virk’s theoretical limit, and had an inversion rate nearly four times as rapid as a standard friction reducer. The dosages of the friction reducer were from 0.25 to 1.00 gallons per thousand gallons of treatment fluid. These friction reducers were tested in a variety of brines in a 10 gallon capacity friction loop through a ½ inch pipe at a Newtonian Reynolds number of 150,000. The data was collected every second during a 10 minute run with 6 specific performance criteria used to rank the candidates.
This study demonstrates it is possible to provide a friction reducer that works well in brine content typical to stimulation fluids that contain a majority of flow back water from previous well treatments. This would allow well service companies to provide quality stimulation fluids of greater brine content and also minimize fluid disposal volumes and affiliated costs. Chemical additives such as these are needed in regions where both water quality and quantity are concerns.
