Page 13 - Air and Gas Drilling Manual

xiv List of Symbols
2
P bm
= pressure at the bottom of the motor cavity, psia
p bm
2
P bp = pressure at the bottom of the motor cavity, lb/ft abs
= back pressure, lb/ft abs
p bp = back pressure, psia
2
P cdci = pressure due to the stop action of the air hammer, lb/ft abs
p cdci = pressure due to the stop action of the air hammer, psia
p d2 = approximated derated output pressure, psia
2
P e = pressure at top of the annulus, lb/ft abs
2
P g = gas pressure, lb/ft abs
p i = input pressure, psia
2
2
P i = pressure entering the first stage of the compressor, lb/ft abs (N/m abs)
2
P iab = pressure inside drill bit above the nozzles, lb/ft abs
p iab = pressure inside drill bit above the nozzles, psia
2
P ias = pressure above the turbine stator, lb/ft abs
p ias = pressure above the turbine stator, psia
2
P in = injection pressure, lb/ft abs
2
P mav = average pressure in the motor, lb/ft abs
p mav = average pressure in the motor, psia
p o = output pressure, psia
2
2
P o = pressure exiting the last stage of the compressor, lb/ft abs (N/m abs)
2
P pl = pipeline pressure, lb/ft abs
p pl = pipeline pressure, psia
PR = power ratio
p r = reference atmospheric pressure, psia
2
P s = surface pressure at the top of the annulus, lb/ft abs
p sat = saturation pressure of air at the annulus bottomhole conditions, psia
p sr = pressure at the entrance end of the line, psia
2
P sr = pressure at the entrance of the surface return flow line, lb/ft abs
p Tee = pressure upstream of the Tee at the top of the annulus, psia