A New Polymer Based Multifunctional Fracturing Fluid With Enhanced Proppant Transport Capability

Abstract

Abstract Multifunctional fracturing fluid is desirable in the oil and gas industry as it can reduce operational complexity and footprints during hydraulic fracturing. Traditional slickwater fracturing fluid has limited proppant transport capability and lacks other functionalities. Most reported publications and practices on proppant transport enhancement were largely realized via increasing the viscosity of the fracturing fluid by using high viscosity friction reducer (HVFR) or simply increasing dosages. Recent multifunctional fracturing fluid research has also demonstrated that the combination of HVFR with nano-emulsion can provide the effect of spontaneous imbibition oil displacement to improve oil recovery (IOR) and thus achieving the goal of combining both hydraulic fracturing and IOR. While fracturing fluid with high viscosity has been used to increase its proppant carrying capability, it comes with the compromise of reduced fracturing length, fewer secondary fractures as well as requiring multiple additives to achieve multifunctionalities. In response to the industrial needs of multifunctional fracturing fluids with reduced operational footprints, we report a multifunctional fracturing fluid based on a novel single polymer system containing oil-displacement surfactant. The new polymer based fracturing fluid was characterized in terms of friction reduction, proppant settling, rheological properties and Amott cell spontaneous imbibition tests. The flow loop results showed that the new polymer system based fracturing fluid can achieve friction reduction of more than 70% in both fresh water and 55K brine. Remarkably, the new fracturing fluid at 0.4wt% can suspend the 20-40 mesh ceramic proppant for an extended period without apparent settling. Breaker studies and rheological properties of the fluid were performed using traditional breaker ammonium persulfate at various dosages. The spontaneous imbibition test on the broken fluid showed a significant increase in oil recovery as compared to the control sample. The results showed that the novel multifunctional fracturing fluid can be used as a traditional friction reducer at low dosages with over 70% friction reduction; while at high dosages, the fracturing fluid exhibits superior proppant carrying capability due to the formation of three-dimensional structures facilitated by hydrophobic association. Additionally, the multifunctional fracturing fluid can be easily broken by traditional peroxide breaker to release the oil displacement surfactant to enhance oil recovery as demonstrated by the spontaneous imbibition test. The presented multifunctional fluid can reduce the number of additives needed in the field and its enhanced proppant transport capability can result in less freshwater usage and less environmental impact.