Numerical simulation of proppant migration in horizontal wells with multi-fracture fracturing

Abstract

For horizontal wells fracturing in unconventional reservoirs, the fracture morphology and proppant migration are severely affected by the interfering effects among multiple fractures propagation. Current numerical simulation for proppant migration did not reveal the interrelation among flow distribution, fracture length and sandbank shape during multiple fractures propagation. In this study, a proppant migration model is proposed by combining the displacement discontinuity method (DDM) and the Eulerian-Lagrangian method (E-L M), which implement dynamic multiple fractures propagation simulation as well as the changing state of flow distribution for each fracture. The accuracy of the numerical model is verified by laboratory experiments. The sensitivity parameters of proppant settlement are analyzed, and two dimensionless parameters, height ratio γ and area ratio η are proposed for proppant migration evaluation. The results show that with a lower fracturing fluid flow rate, fluid viscosity, the height ratio γ is lower, and the area ratio η is higher, which also results in the proppant being more likely to accumulate at the fracture entrance. As the proppant particle size increases from 100 μm to 500 μm, the dimensionless height ratio γ and the dimensionless area ratio η decrease significantly. Increase in fracture spacing during horizontal well multi-cluster fracturing results in a limited improvement for proppant settlement. Formation elastic modulus has an appreciable impact on proppant migration in multi-fracture propagation, high elastic modulus formation leads to an ununiform proppant placement over long distances.