Changes

The hydraulic horsepower at the bit (BHhp) is calculated as for total hydraulic horsepower (THhp), but the mud pump pressure (Pp) is replaced by the jet nozzle pressure loss (JNPL):

The hydraulic horsepower at the bit (BHhp) is calculated as for total hydraulic horsepower (THhp), but the mud pump pressure (Pp) is replaced by the jet nozzle pressure loss (JNPL):

:<math>\mbox{BHhp} = (1169 \times 400)/1714 = 273 \mbox{ hp}</math>

:<math>\mbox{BHhp} = \frac{1169 \times 400}{1714} = 273 \mbox{ hp}</math>

The ''percentage'' of the total hydraulic horsepower expended at the bit is an important parameter to determine and is calculated in two ways:

The ''percentage'' of the total hydraulic horsepower expended at the bit is an important parameter to determine and is calculated in two ways:

:<math>\% \mbox{ Hhpb} = (\mbox{BHhp/THhp}) \times 100</math>

:<math>\% \mbox{ Hhpb} = \frac{\mbox{BHhp}}{\text{THhp}} \times 100</math>

or

or