Calculation of both hydraulic horsepower and impact force mainly depends on calculating pressure drop across the bit. A major percentage of normal circulating pressures is lost by pumping through the nozzles when jet bits are used. Here you shall understand Hot to perform Oilfield Drilling Bit Hydraulics Calculations & download its calculator Excel.
The pressure loss is not frictional pressure but rather acceleration forces. Assumptions generally made are
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1) the changes in pressure resulting from a change in elevation are negligible.
2) the upstream velocity (V.) is negligible compared to downstream
Example On How To Calculate bit pressure drop, Hydraulic Horse Power And Impact Force
Calculate the drill bit pressure drop, hydraulic horsepower and impact force for the following set of conditions:
Mud weight = 14.5 Ib/gal
Flow rate = 300 gal/min
Jet sizes = three 12/32 in. jets
1. Determine the nozzle area, AT:
AT = 3 x π /4 x (d)^2 = 0.331 in^2
2. Eq.3 is used to calculate the pressure drop at the bit:
PB = (300)^ 2 x 14.5 / ( 0.95^2 x 0.331 ^2 x 12028) = 1097 psi
3. Calculate the hydraulic horsepower expended at the bit from Eq.4
HHP = (1097 psi x 300 gal/min) / 1714 = 192 hp
4. The hydraulic impact force due to pressure loss through the drilling bit is computed from Eq.5
Fi = 0.01823 x (0.95) x (300) x ((14.5)(1,097))^(1/2) = 654 Ib
Bit Hydraulics Calculator Excel Sheet
Download Bit Hydraulics Calculator Excel Sheet
A simple excel sheet to be used on drilling rig to calculate pressure drop and perform drilling hydraulics run.