Successful Slickwater Fracturing in Ultrahigh TDS Produced Water by Novel Environmentally Preferred Friction Reducer

Abstract

Fluid volumes in fracturing treatments have increased substantially, while water supply has become more of a public concern. Rather than paying to treat and dispose of produced and flowback water, operators would like to reuse it in subsequent stimulation treatments. Produced water with high total dissolved solids (TDS) and high divalent cation content poses extreme challenges for emulsion friction reducers because cations hinder the inversion of friction reducers and cause loss of efficiency of friction reduction. Treating produced water to the quality suitable for conventional fracturing fluids is time-consuming and often cost-prohibitive.A salt-tolerant friction reducer was developed to address the challenges of high-TDS produced water. In a produced water sample with high TDS and high total hardness, the new polymer hydrates within 10 seconds and gives a friction reduction profile similar to that of current inverse-emulsion friction reducers in fresh water. The fluid is compatible with other common stimulation additives such as scale inhibitors, biocides, clay stabilizers, surfactants, and breakers.The paper discusses field test results and production response from slickwater fracturing operation in Delaware basin with produced water containing more than 250,000 ppm TDS and 60,000 ppm total hardness. Head-to-head comparison with conventional crosslinked fluids and friction reducers under field conditions showed significant oil and gas production improvement resulting from increased fracture complexity by pumping low viscosity fluids at higher pumping rate in extremely high-TDS produced water. It provides the oilfield industry a cost-effective solution of reducing produced water disposal and fresh water demands, thereby ultimately improving environmental and economic impacts of well operations.

Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

“…Then, to make multifunctional variableviscosity slick water or high-viscosity slick water, a certain concentration of CNI-A and CNI-B reagents has been applied to clear water, the data of pressure drop of the fluid are obtained after going through the pipeline, and the solution's drag-reducing rate is calculated. 34,35 The drag-reducing rate is computed as eq 2…”

“…Next, the pressure drop of clear water flowing without a reagent has been measured. Then, to make multifunctional variable-viscosity slick water or high-viscosity slick water, a certain concentration of CNI-A and CNI-B reagents has been applied to clear water, the data of pressure drop of the fluid are obtained after going through the pipeline, and the solution’s drag-reducing rate is calculated. , The drag-reducing rate is computed as eq DR refers to the drag-reducing rate, %; Δ P O refers to the pressure drop of clear water flow when no reagent is added, Pa; and Δ P DR refers to the pressure drop of the slick water after the addition of the reagent, Pa.…”

A Non-Damaging Friction Reducing Agent for Slick-Water Fracturing

“…Friction reducer was used as a major composition of the slickwater fracturing fluid, which could lower the surface pumping pressure by minimizing the energy loss by changing the turbulent flow to laminar flow (Ke et al 2006;White and Mungal 2008;Aften 2010;Sun et al 2010, Kolla et al 2013Ozuruigbo and Fan 2014;Sareen et al 2014;Zhou et al 2014;Guerin et al 2015). Currently, most of the friction reducers are polyacrylamide (PAM) based copolymers (Kaufman et al 2008;Paktinat et al 2011b;Sun et al 2011).…”