High Viscosity Friction Reducer that Minimizes Damage to Conductivity

Abstract

Friction reducers (FRs) are commonly used in Slickwater fracturing operations to enhance oil and gas production. They are essential in reducing the frictional forces that develop along the pipe wall while pumping at high flow rates while placing proppant into fractures created in reservoirs. Standard friction reducers were historically designed for potable water and to carry proppant into the reservoir by pumping fluids at a high flow rate. They were designed to utilize turbulence for transport, however their proppant carrying capacity is limited. To maximize proppant loading into these unconventional wells, High Viscosity Friction Reducers (HVFRs) have been successfully introduced. They have the ability to reduce water consumption, minimizing chemical usage and require less operating equipment on location. Most importantly, they have better proppant transport capability which keeps the fractures in the rock open for long term production. However, some concerns remain of potential conductivity damage that might occur when using these high molecular weight polyacrylamide-based fluids, that constitute a HVFR, at higher concentrations. All current friction reducers are polymers with C-C backbones, which have historically been difficult to degrade on their own. Test show that these polymers can cause conductivity damage even in the presence of oxidizer breakers if not properly selected for the reservoir conditions. A novel HVFR design was developed to minimize formation damage when fracturing designs call for the use of HVFRs. The chemistry was engineered to be self-breaking at low concentrations, causing the bonds in the polymer to hydrolyze with elevated temperature and exposure over time. This approach results in a reduction of the residue left in the proppant pack upon flowback for a better clean-up process. This HVFR was used in a Permian field, where the operator saw an increase of 150% over the expected production that continued through the writing of this paper 90+ days. This paper will discuss the laboratory work done to evaluate the reduction of conductivity damage to the proppant pack as well highlight how this new engineered design translated into improved estimated ultimate recovery (EUR) on field trials in the Permian basin.