Numerical Study on Crushing Strength of Porous Proppant Using the Finite Element Method

Porous proppants are an important type of lightweight proppants, which can be transported to far fractures in hydraulic fracturing. The ideal proppants should have higher strength besides lower density. Usually, as the pores increases, the crushing strength of porous proppants will decrease, resulting in the difficulty propping more fractures. In this study, the three-dimensional finite element model (3D-FEM) was used to study crushing strength of single proppant. The effects of pore distribution, pore size and porosity on proppant crushing strength were analyzed. Weibull theory was used to describe the dispersion of crushing strength. The failure processes of solid proppant and porous proppant were studied. The results show that the solid proppant has obvious brittle fracture, while porous proppant has structural plasticity. With the increase of pore size and decrease of porosity, the distribution of crushing strength is more dispersed. The crushing strength decreases significantly when porosity is less than 7% and then decreases slowly as porosity continues to increase. The crushing strength will increase with the increase of pore size. When the pore size is larger than 0.1 mm (d/D<1/6), the crushing strength has no obvious change. These results can guide the preparation and application of porous proppants.