Mechanics of light weight proppants: A discrete approach

The computational and experimental assessment of light-weight proppants are undertaken to identify their effectiveness and efficiency to replace sand enlisted in hydraulic fracturing treatments in oil or gas well operations. A mixture of ground-nut-shells, aluminum or ceramic particles are shown to reduce the viscosity of the fracturing fluid while increasing its resistance to compression. Herein explicit dynamic finite element method is implemented to study quasi-static compression of a proppant pack where each granule (particle) is modeled individually. Various mixtures of hard and soft particles are investigated as a function of shape, size and inter-particle friction. The particle interactions clearly illustrate changes in pore space as a function of pressure, mixture composition and friction. The pressure vs displacement response of a proppant pack reflects strong dependence on mixture composition and initial particle configuration and has been compared with the test data. Friction leads to higher porosity by limiting particle rearrangement. Models reveal that softer rock with a mixture of hard and soft particles inhibit flowback but may decrease the pack permeability.