A new system that integrates friction-reducer (FR) chemistry with geochemical modeling and water remediation techniques enables the economic reuse of fracture flowback fluid from slickwater fracturing operations.

According to developers of the Gamma FRac system, nearly any water can be reused with this approach, and in some applications, the technology has eliminated disposal costs. This sub-solution is an anion- and cation-tolerant fluid that incorporates the synergistic roles of four additives that are used in the preparation of flowback water.

The first is salt-tolerant nano-particle friction reducer (STFR), a liquid-polymer FR emulsion that is brine tolerant and non-damaging; it is designed especially for use in shale formations and environmentally sensitive applications. The additive incorporates patented nano-particle technology that decreases imbibition, thereby reducing formation damage. This FR chemistry — used at lower concentration than typical FRs — reduces friction pressures by 50 to 75%, permitting a significant reduction in wellsite hydraulic horsepower. It has high salt tolerance in brines up to 12% NaCl, enabling the reuse of fracturing flowback waters and produced formation waters for fracturing.

A new system that integrates FR chemistry with geochemical modeling and water remediation techniques enables the economic reuse of fracture flowback fluid from slickwater fracturing operations.

The second is neutral-pH iron control, an iron-control (IC) agent that maintains iron in a stable complex, preventing precipitation of iron scales, enhancing FR, and enabling use of flowback water. This agent is game changing in that it:

• Prevents precipitation of post-frac geochemical species such as siderite (which can form in situ);

• Is synergistic with other scale inhibitors; and

• Has no adverse side effects to FR chemistry.

A key benefit of this IC agent is reduction in chemical loading while preserving a neutral pH (a unique IC property). The additive has been shown to enhance calcium tolerance that stabilizes sulfate and carbonate control constituents and aids in the post-frac breakdown of FR polymer.

Third is multifunction scale control (MFSC). A blended scale-control agent, Super TSCTM, is a scale-control agent that simultaneously protects against three types of geochemistry: carbonate, sulfate, and iron-based scale depositions. Unprotected, the downhole environment can lead to formation of geochemical precipitates within the created fracture network and potential scale accumulation in perforations or tubulars. MFSC is designed for compatibility with the STFR and is suited to enhance post-frac flowback performance in shale-fracturing operations while enabling water reuse.

The fourth is aqueous biomass control (ABC) for controlling bacteria and other bio-fouling microfauna, ABC is integrated with a biocide that provides quick kill yet degrades rapidly in the environment. The biocide mitigates sulfate-reducing bacteria, the microorganisms that cause downhole H2S souring. It also controls chemosynthetic microbes such as acid-producing bacteria, iron-producing bacteria, and slime-forming bacteria at low dosage.