Post-treatment production analyses after hydraulic fracturing with crosslinked gel or slickwater often indicate that the treatment did not achieve the designed fractured area, which could be attributed to non-ideal proppant placement in the fracture. Although crosslinked gel provides good proppant suspension, it may not provide the desired proppant transport under downhole conditions. It is also difficult to clean up and thus induces gel damage into the proppant pack and formation. Slickwater treatment reduces gel damage, but proppant settling and banking problems can reduce the chance of achieving optimal fracture conductivity. Several proppant placement techniques have been developed to generate highly conductive paths for hydrocarbons to flow from an unconventional reservoir to the wellbore, such as hybrid fracturing, ultralightweight proppant delivery, and reverse hybrid fracturing.
This paper demonstrates a novel fracturing fluid and its nearly perfect proppant transport characteristics. An engineered method of applying such fluids to optimize proppant placement and maximize fracture conductivity is discussed. The novel fracturing fluids are based on preformed gel fluids. When properly selected, the fluids can ideally suspend proppant under downhole conditions and carry all types of proppants into the fracture. This leads to better transverse and vertical placement of proppant in the fracture and significantly increases the fractured surface area, which is one of most important factors in unconventional reservoir production. The degradability of the fluid can be controlled by reservoir temperature, fluid pH, or breaker loading, which leads to optimized proppant pack conductivity.
This paper discusses the evolution of the technology and laboratory testing results for this unique fluid system. The system has applications in areas requiring high fractured surface area and high regained conductivity, such as unconventional liquids-rich formations.