Formation mechanism of proppant particle voidage distribution in hydraulic fracturing fractures

Abstract

In order to understand the proppant particle voidage evolution of the hydraulic propped fractures, the numerical simulation method was used to simulate the compression process of the proppant particle in fracture under different closed stresses. The formation mechanism of void distribution of the proppant particle in fracture was revealed by investigating the distributions of contact force and coordination number of the proppant particles in fracture. The results showed that the proppant particle voidage distribution from the bottom to top was as follows: decreasing slowly, decreasing sharply, decreasing slowly, increasing sharply, increasing slowly. The propped fractures were divided into three different layers: bottom, middle and top layers under the same stress state, the bottom proppants with the weakest contact force was the stress attenuation zone. In this zone, the average coordination number was the smallest and the void ratio was the largest. The middle proppant with the strongest contact force was the stress bearing zone. In the area, particles had the weakest ability to transmit force downwards, the average coordination number was the largest and the void ratio was the smallest. The top particles with the strongest ability to transmit force downwards were called the stress transfer zone. In this area, the contact force between the proppants was weak, and the average coordination number and void ratio were between those of the stress bearing zone and stress attenuation zone, respectively.

Keywords

• mining face
• bedding drilling borehole
• staged hydraulic fracturing
• double packer
• permeability enhancement effect