New Generation of Expandable Diverter for Well Stimulation: Preparation, Properties and Performance Evaluation

Abstract To enhance the productivity of unconventional reservoirs, it is essential to create extensive fractures or worm-like networks in the formation during well stimulation. Using effective diverters can increase the number of fractures, thereby reduce the number of fracturing stages and consequently lower operational costs and boost well productivity. To address the challenge, a new generation of diverter has been developed using elastic polymeric particles with good expandability and degradability, based on polyurethane chemistry. The effect of synthesis conditions, such as the prepolymer concentration and agitation speed on the particle size and material properties has been studied. The chemical composition, thermal stability, morphology/microstructure, and elasticity of these materials have been characterized using FTIR, TGA, SEM and uniaxial compression tests. The plugging performance of the polymeric diverter was examined. By adjusting the synthesis conditions, the particle size of the synthesized polymeric diverter can be easily tuned in the range of 0.2 – 8 mm. Characterization results confirm the presence of both polyurea and polyurethane structures, as well as good thermal stability for subsurface wellbore operations. Compression experiments demonstrate the excellent elasticity of the materials, showing that the diverter can quickly return to its original shape and size once the compression stress is released. In the plugging performance tests, the diverter material completely blocked fluid flow at a slot size of 2 mm and 4 mm. As the slot size gradually increased from 0.3 mm to 3 mm, no drop in differential pressure was observed, indicating continuous sealing during multiple fracture initiation and propagation processes. The dynamic temporary plugging performance evaluation clearly shows the efficiency of the newly developed diverter, thus enhancing well productivity. The newly developed diverter material shows great promise for diversion applications. It can improve the efficiency of multi-staged fracturing, thereby reducing the total number of stages, and ultimately the associated operational time and costs. Furthermore, due to its unique properties and degradability, this material holds high potential for use in water shut-off application as well.