Page 18 - Air and Gas Drilling Manual

Γ
= foam quality at the bottom of the annulus
Γ bh
= foam quality at the top of the annulus upstream from the back pressure valve
Γ bp = foam quality xix List of Symbols
Γ sfa = foam quality exiting the cased annulus and starts into the Tee
Γ sfbh = foam quality at the bottom of the annulus
γ = specific weigh of the, lb/ft 3
γ ah = approximate specific weigh of air inside the drill collars entering the air
hammer, lb/ft 3
γ ai = specific weight of air above the drill bit inside the drill pipe, lb/ft 3
γ bh = specific weight of the air at bottomhole pressure and temperature conditions,
lb/ft 3
= specific weigh of the gas (air) upstream of the back pressure valve, lb/ft 3
γ bp
γ cdci = new specific weight of compressed air in the drill collars, lb/ft 3
3 3
γ f = specific weight of the incompressible drilling fluid, lb/ft (N/m )
γ g = specific weight of the gas, lb/ft 3

γ ga = approximate specific weight of gas exiting the cased annulus and starts into the
Tee, lb/ft 3
γ gi = specific weight of gas entering the drill string, lb/ft 3
γ m = specific weigh of the drilling mud (fluid), lb/ft 3
γ mav = average specific weight of air in the motor cavity, lb/ft 3

γ mix = specific weight of the mixture of air (or other gas), incompressible fluid, and
3
rock cuttings, lb/ft
3
γ mixai = mixture specific weight above the drill bit inside the drill string, lb/ft
γ mixbh = mixture specific weight at the bottom of the annulus, lb/ft 3
3
3
γ s = specific weight of the solid rock cuttings, lb/ft (N/m )