Experimental Study of Self-aggregating Proppants: New Approaches to Proppant Flowback Control

Abstract

Due to the high rate of proppant flowback after hydraulic fracturing stimulations, surface modified quartz sand proppants with excellent proppant flowback control abilities, self-aggregating proppants, were prepared. These surface modified proppants can aggregate together spontaneously and form a proppant column in water based liquid environment. Analyses show that the strong hydrogen bonds contribute to the absorption of the surface modifier onto the proppants, and the softening effect of the water to the polymer coating prompts the connection between the proppants. Scanning electron microscope pictures show that proppant particles are stacked together tightly. The stable structure contributes to the macroscopic stability of the proppant column. The maximum sand free flow rate of the model packed with modified proppants is 2.8 times larger than that of untreated proppants by average, indicating that the self-aggregating proppants exhibit excellent proppant flowback control abilities. In addition, fines control tests show that the modified proppants can also prevent the migration of the formation fines effectively, reducing the conductivity loss caused by particle migrations. By virtue of the reaggreating property and the encapsulation action of polymer coating to the crushed fragments, the fracture conductivities are increased by 3 times even at large closure stresses. The results provide a new alternative for proppant flowback control while do little damage to the permeability of the proppant pack.

Review of Developments in Nanotechnology Application for Formation Damage Control

“…A large volume of proppants is pumped into the formation to enhance transportation of shale gas from the formation to the wellbore in commercial quantities. − Such production requires the complex network of artificial fractures to have sufficient conductivity to sustain the whole period of production . Unfortunately, the techniques for transporting and placing proppants in the formation to hold the fractures exhibit formation damage near the fracture surface that affects fracture packing. − Many mechanisms impair the fracture conductivity during the process of fracturing. ,, These include proppant embedment, closure stress effect, , proppant crushing, , cyclic stress, fine migration, proppant pack diagenesis, , and the blockage caused by the gel residue in the proppant pack and gel filter cake at the fracture face. , …”

“…146−148 Many mechanisms impair the fracture conductivity during the process of fracturing. 145,148,149 These include proppant embedment, 150 closure stress effect, 151,152 proppant crushing, 153,154 cyclic stress, 148 fine migration, 155 proppant pack diagenesis, 156,157 and the blockage caused by the gel residue in the proppant pack and gel filter cake at the fracture face. 158,159 Recent studies have demonstrated that the use of nanoparticles can improve and control formation damage during stimulation 8 compared to conventional methods.…”