Abstract
Final proppant distribution inside hydraulic fractures which depends on particle properties, movement and deposition highly impact wellbore productivity and consequently is crucial in modeling and design of hydraulic fracturing. This paper presents a thorough review of laboratory scale tests performed on proppant transport related to hydraulic fracturing treatments and governing physics behind its mechanisms.
The interaction between fluid (gas and liquid) and solid particles has been investigated in applied mathematics and physics. In such phenomena, there is always a relative motion between particles and fluids. In this work this relative motion during proppant movement, sedimentation and fluidization in both small- and large-scale lab tests have been assessed in detail. Existing correlations which relate proppant particles settling velocity to concentration of proppant particles, fracture wall and inertia effect in Newtonian and non- Newtonian fluid are presented as well.
Lab tests show that various parameters determine the proppant particles distribution inside the fractures. Particle settling velocity, an influential parameter in this regard, is impacted by fracture walls, inertia and the presence of other particles. Inertia changes the relation of drag coefficient and Reynold number. Fracture wall and particles concentration decrease settling velocity as drag force increases. At a certain level, concentration reaches to its limit. Proppant concentration, in addition, increases the suspension viscosity, fracture width and net pressure. However, it deceases the fracture length as more pressure loss occurs along the fracture. As a result, well productivity is highly impacted by the proppant settling and distribution.
Many studies have been devoted to identifying different aspects of hydraulic fracturing and proppant transport mechanisms in porous media. This study highlights the key parameters and their effects, existing correlations and physics behind them for better understanding and management of this mechanism.
