b- Pressure Drop

((Refers to the pressure required to overcome the friction between the drilling fluid and specific system section))​

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1- Drill String Pressure Drop.​

2- Annulus Pressure Drop.​

3- Bit Pressure Drop.

​1- Drill string pressure drop

((Refers to the pressure required to overcome the friction between the drilling fluid and drill pipe))

2- Annulus Pressure Drop

• ((Refers to the pressure required to overcome the friction between the drilling fluid and annulus))​
• ECD (Equivalent Circulating Density):-​

  is the combined pressure being exerted hydrostatically by the mud and the mud pump when the system is circulating.​

• Slip Velocity:-​

is the rate at which cuttings fall back toward bottom.

3- Swab & Surge Pressure

• Swap pressure is a negative value produced by pipe movement up ward.​
• Surge pressure is a positive value produced by pipe movement down ward.​

​4- Bit Hydraulics

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• Bit Pressure Drop.​
• Jet Velocity.​
• Hydraulic Horse Power.​
• Impact Force

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