What Does Bottomhole Pressure (BHP) Mean?
Bottomhole pressure (BHP) (or downhole pressure) is the pressure measured at the bottom of the hole in pounds per square inch (psi). It is the sum of the different pressures acting downhole or at the bottom of the drilled hole.
For non-flow conditions, the downhole pressure is caused by the hydrostatic pressure exerted by the fluid in the wellbore and surface pressure. For flow conditions, when wellbore fluid is being circulated, it is the sum of the hydrostatic pressure and the friction pressure drop in the annulus.
Trenchlesspedia Explains Bottomhole Pressure (BHP)
The downhole pressure or BHP for non-flow conditions can be calculated using the formula: BHP = Mw x D x 0.052
Here, Mw is the mud weight in pounds per gallon
D is the true vertical depth in feet, and 0.052 is the conversion factor when the above units are used for measurement.
For flow conditions, the BHP increase with the amount of fluid friction in the annulus. To prevent the influx of formation fluid into the wellbore, the BHP should exceed the formation pressure.
However; a weak formation can fracture and lose wellbore fluid if BHP, including the added fluid friction pressure of the flowing fluid, is too high.