Bottomhole Annulus Pressure
Bottomhole annulus pressure, abbreviated as BHP, is the pressure in the annular space between the wellbore and the drill string at the bottom of the well. This pressure is needed for managing well stability, preventing wellbore collapse, and maintaining control over the well to prevent blowouts or kicks.
Bottomhole Annulus Pressure Formula |
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\( \rho_a \;=\; BHP \;/\; 0.052 \; h \) \( h \;=\; BPH \;/\; 0.052 \; \rho_a \) |
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| Symbol | English | Metric |
| \( BHP \) = Bottomhole Annulus Pressure (psi) | \(lbf \;/\; in^2\) | - |
| \( \rho_a \) (Greek symbol rho) = Annulus Fluid Density (ppg) | \(lbm \;/\; gal\) | - |
| \( h \) = Annulus Vertical Height | \(ft\) | - |
Key Points about Bottomhole Annulus Pressure
Mud Weight (Density) - Heavier drilling mud creates more hydrostatic pressure, contributing to the annulus pressure.
Pump Pressure and Flow Rate - Circulating drilling fluids generate pressure from friction in the annulus, increasing BHP.
Well Depth and Geometry - Pressure builds with depth, and the design of the wellbore (narrow sections or wider sections) affects annular pressure.
Temperature - Temperature changes with depth can affect fluid density and thus alter pressure in the annulus.
Formation Pressure - Understanding BHP helps manage formation pressures and maintain safe drilling conditions.
