Changes

Pump pressure is the total pressure expended throughout the circulating system's surface equipment (such as the standpipe, kelly hose, and kelly), drill string bore, jet nozzles, and annulus. Only the pressure expended through the jet nozzles accomplishes useful work for drilling. The remaining pressure losses are referred to as ''parasitic pressure losses''. Jet nozzle pressure loss is estimated as follows:

Pump pressure is the total pressure expended throughout the circulating system's surface equipment (such as the standpipe, kelly hose, and kelly), drill string bore, jet nozzles, and annulus. Only the pressure expended through the jet nozzles accomplishes useful work for drilling. The remaining pressure losses are referred to as ''parasitic pressure losses''. Jet nozzle pressure loss is estimated as follows:

:<math>\mbox{JNPL} = (\mbox{MW} \times \mbox{GPM}^{2})/(10{,}858 \times \mbox{An}^{2})</math>

:<math>\mbox{JNPL} = \frac{\mbox{MW} \times \mbox{GPM}^2}{10{,}858 \times \mbox{An}^2}</math>

'''''Example''''': The pressure lost through three 13′s jet nozzles while circulating a 12.0-ppg mud at 400 gal/min is

'''''Example''''': The pressure lost through three 13′s jet nozzles while circulating a 12.0-ppg mud at 400 gal/min is

:<math>\mbox{JNPL} = (12 \times 400^{2})/(10{,}858 \times 0.3889^{2}) = 1169 \mbox{ psi}</math>

:<math>\mbox{JNPL} = \frac{12 \times 400^2}{10{,}858 \times 0.3889^2} = 1169 \mbox{ psi}</math>

===Hydraulic horsepower at the bit===

===Hydraulic horsepower at the bit===