Calibration of the Interaction Parameters between the Proppant and Fracture Wall and the Effects of These Parameters on Proppant Distribution

Mingzhong Li,Chunting Liu,Guodong Zhang

doi:10.3390/en13082099

Abstract

Saltation and reputation (creep) dominate proppant transport rather than suspension during slickwater fracturing, due to the low sand-carrying capacity of the slickwater. Thus, the interaction parameters between proppants and fracture walls, which affect saltation and reputation, play a more critical role in proppant transport. In this paper, a calibration method for the interaction parameters between proppants and walls is built. A three-dimensional coupled computational fluid dynamics–discrete element method (CFD–DEM) model is established to study the effects of the interaction parameters on proppant migration, considering the wall roughness and unevenly distributed diameters of proppants. The simulation results show that a lower static friction coefficient and rolling friction coefficient can result in a smaller equilibrium height of the sand bank and a smaller build angle and drawdown angle, which is beneficial for carrying the proppant to the distal end of the fracture. The wall roughness and the unevenly distributed diameter of the proppants increase the collision between proppant and proppant or the wall, whereas the interactions have little impact on the sandbank morphology, slightly increasing the equilibrium height of the sandbank.

Highlights

Slickwater is widely used during hydraulic fracturing in unconventional reservoirs to form complex fracture networks
Kern et al [8] conducted the earliest work on slot flow experiments, and the results showed that the proppants would settle out of fluid and form a dune near the wellbore, and that proppants can be transported further into fractures only if the dune reaches the equilibrium height
The coupled computational fluid dynamics–discrete element method (CFD–discrete element method (DEM)) model was established considering the interaction between proppants and walls to study the mechanisms of proppant transport in fracture and to analyze the impacts of the interaction parameters on proppant distribution considering the wall roughness and unevenly distributed diameter of proppants

Summary

Introduction

Slickwater is widely used during hydraulic fracturing in unconventional reservoirs to form complex fracture networks. It is used for its low cost and little damage it presents to reservoirs [1,2,3,4,5,6]. Experimental research over the years significantly contributed to our understanding of the mechanisms of proppant transport in low-viscosity fluids. Kern et al [8] conducted the earliest work on slot flow experiments, and the results showed that the proppants would settle out of fluid and form a dune near the wellbore, and that proppants can be transported further into fractures only if the dune reaches the equilibrium height. Woodworth et al [11] used the results of laboratory experiments to analyze the influences of fluid viscosity, fluid density, pump rate, proppant size and density, proppant concentration, and fracture width on proppant transport in a Energies 2020, 13, 2099; doi:10.3390/en13082099 www.mdpi.com/journal/energies

Methods

Discussion

Conclusion