Nearly Perfect Proppant Transport by Particle Fracturing Fluids Yields Exciting Opportunities in Well Completion Applications

Abstract

Abstract Reservoir completion techniques, such as hydraulic fracturing for low permeability wells and frac pack for unconsolidated formation treatments, are normally applied to increase well productivity. The production of treated wells can be greatly enhanced by increased propped fracture area and proppant pack conductivity, both of which are highly dependent on proppant distribution in the fracture. Stimulation fluids with high viscosity are traditionally employed to open fractures and carry proppant into created fracture area in the formation. Although conventional crosslinked fluids are observed to provide good proppant suspension in laboratory environments, they might not provide the desired proppant transport under downhole conditions. Crosslinked fluids can be difficult to clean up, due to residual gel damage to proppant pack and formation. Post-treatment production analyses with crosslinked gel often indicate that the treatment did not achieve the designed conductive fracture area, which could be attributed to non-ideal proppant placement and/or significantly damaged fracture conductivity. Perfect proppant suspension and transportation under downhole conditions is the ultimate dream for any fracturing fluid technology as it suggests proppant placement throughout the created fracture area to maximize stimulation efficiency of the treatment. Unlike conventional fracturing fluid technology which uses fluid rheology, polymer chains overlap and inter-chain crosslinking to generate viscosity, as the way to suspend proppant. The new concept involves a novel approach of particle packing mechanism to provide the near perfect proppant suspension in the new fluid, while maintaining minimum formation and proppant pack damage after breaking with frac fluid breakers. As to proppant transport mechanics with conventional fluids, viscosity and velocity above threshold levels can move proppant in a generally horizontal direction until gravity prevails as the velocity decays. However, neither viscosity nor velocity can overcome gravity to effectively move proppant upwardly from the wellbore. The packing mechanics of the soft particle fluids substantially mitigate the effects of gravity until such time as fracture closure confines the proppant. This paper discusses laboratory results for this unique particle fluid system (1) to enhance proppant carrying capacity, (2) to deliver significantly better proppant vertical distribution of the fracture, (3) and to yield near 100% regained proppant pack conductivity. The system can unlock reservoir potential in areas requiring high propped fracture area and high regained conductivity, such as unconventional liquid-rich and offshore unconsolidated formations.