Friction factor in a drill pipe, abbreviated as t, a dimensionless number, used to quantify the resistance encountered by the drilling fluid as it flows through the drill pipe and the annulus. The friction factor is used for calculating pressure losses, optimizing drilling fluid properties, and ensuring efficient and safe drilling operations.
Friction Factor in Drill Pipe Formula |
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| \( f \;=\; \dfrac{ \eta_s }{ 1 + (\; \eta_s \cdot \sigma \cdot ( \; ( v_t + \omega^2 )^{0.5} \; ) \cdot e \cdot t ) }\) | ||
| Symbol | English | Metric |
| \( f \) = Friction Factor | \(dimensionless\) | - |
| \( \eta_s \) (Greek symbol eta) = Static Viscosity | \(lbf - sec \;/\; ft^2\) | - |
| \( \sigma \) (Greek symbol sigma) = Nominal Stress at Contact | \(lbf \;/\; in^2\) | - |
| \( v_t \) = Drill Bit tip Speed | \(ft \;/\; sec\) | - |
| \( \omega \) (Greek symbol omega) = Angular Speed | \(deg \;/\; sec\) | - |
| \( e \) = Exponential Constant | \(2.718,281,828,...\) | - |
| \( t \) = Average Contact Time | \(sec\) | - |
