Improved Friction Reducer for Hydraulic Fracturing

Abstract

An improved polyacrylamide friction reducer delivered in an inverse emulsion form has been developed for use in fresh water up to 2% KCl. The main benefits realized were an increased level of friction reduction along with an enhanced rate of inversion. These benefits were obtained without compromising the emulsion storage stability. These improvements were gained primarily by optimizing the breaker surfactant package used to release the polymer from its delivered form into the aqueous based treatment fluid.Friction reducers are often a significant portion of the aqueous based chemical stimulation package used in either the stimulation and/or completion of oil/gas wells. Common friction reducers used for fresh water operations typically have a decline in performance when exposed to aqueous based fluids of increased salt content. The performance decline is not solely due to the nature of the polymer, but rather the mechanism of polymer release from its inverse emulsion state. The presence of salt not only affects the polymer configuration but also the ability of the inverse emulsion to release the polymer from its water internal phase into the water continuous stimulation fluid.The new friction reducer was developed by examination of various surfactants by way of simple additions to ternary mixture designed experiments. A variety of bench top performance tests were used to narrow the selection yielding a final surfactant package. The final candidates were then screened using an in-house friction loop. The improved friction reducer dosed at 0.5gpt had a 29% increase in ultimate friction reduction in fresh water and a 119% increased performance in 2% KCl when compared to a standard friction reducer of similar charge and molecular weight. Ultimate performance enhancement was gained within reasonable raw material costs and stability limits.With the increased ultimate friction reduction and superior inversion rate, this new product will reduce the energy required to deliver a specific volume at a set rate or increase the rate of the delivered volume at the same power for water based systems containing up to 2% KCl for stimulations and/or completions.

Study of Friction Reducers for Recycled Stimulation Fluids in Environmentally Sensitive Regions

“…The friction reducer is usually a water soluble synthetic or natural polymer. This reduction effect is described in a previous paper (Aften, et al 2009). One of the most common type of friction reducers are inverse emulsions of a water internal phase containing the polymer dispersed in an oil continuous phase.…”

The New Reality of Hydraulic Fracturing: Treating Produced Water is Cheaper than Using Fresh

“…Polyacrylamide also happens to be the main active ingredient in slickwater friction reducers (Aften and Watson 2009) and tends to show up in early produced waters, along with reduced ferrous iron species. When contacted by chlorine dioxide, ferrous iron is oxidized to its ferric state.…”

Quantitative characterization of polyacrylamide–shale interaction under various saline conditions

“…Water-based mud (WBM) is the most commonly used type of drilling fluid, and shale is highly sensitive to the additives and the clays present in the WBM (Gomez and He 2012;He et al 2014). The common additives used in WBM are friction reducers, acids, gellants, crosslinkers, clay controlling agents and other polymers (Harris 1988;Aften and Watson 2009). It is important to use all the necessary additives in injected fluids, but it is also equally important to use additives that do not potentially weaken the shale.…”