Proppant Settling Velocity Calculator
Calculate proppant settling velocity using Stokes law and intermediate-regime drag correlations. Optimize fluid viscosity for proppant transport.
Input Parameters
Stokes: Vs = dp² (ρp − ρf) g / (18μ) | Re = ρf Vs dp / μ
Intermediate (Re 2-500): CD = 24/Re + 6/(1+√Re) + 0.4
Settling Velocity
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Reynolds Number
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Drag Coefficient
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Flow Regime
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Settle Time (across width)
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Settle Distance in 1 min
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Settling Velocity vs Fluid Viscosity
How this was calculated
Stokes Law (Re < 2): Vs = dp^2 * (rho_p - rho_f) * g / (18 * mu). Valid for creeping flow around a sphere.
Intermediate regime (2 < Re < 500): Uses the Schiller-Naumann drag correlation: CD = 24/Re * (1 + 0.15*Re^0.687). Settling velocity is solved iteratively.
Newton regime (Re > 500): CD ~ 0.44. Vs = sqrt(4*dp*(rho_p-rho_f)*g / (3*CD*rho_f)).
Units: All internal calculations use consistent CGS units, then converted to field units for display.
Assumptions: Spherical particles, Newtonian fluid, infinite medium (no wall effects), single particle (no hindered settling).
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Book a free strategy call →Understanding Proppant Settling in Hydraulic Fractures
Proppant settling velocity is a critical parameter in hydraulic fracturing design. If proppant settles too quickly, it accumulates at the bottom of the fracture before reaching the tip, resulting in poor fracture conductivity in the upper portion of the pay zone. Conversely, if the fluid viscosity is too high, pumping pressures increase and formation damage from polymer residue worsens.
The settling behavior depends on the particle Reynolds number. At very low Re (< 2), Stokes law applies and settling velocity is proportional to the square of particle diameter and inversely proportional to viscosity. At intermediate Re (2-500), inertial effects become significant and the drag coefficient deviates from the Stokes solution. Most frac operations fall in this intermediate regime.
Modern slickwater completions use low-viscosity fluids (2-10 cp) with fine-mesh proppant (40/70, 100 mesh) to achieve adequate transport. Crosslinked gel treatments use higher viscosity (200-1000 cp) with coarser proppant (20/40) for conventional frac designs. This calculator helps engineers quickly evaluate the tradeoff between proppant size, fluid viscosity, and settling rate.
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