STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

874 Drilling and Well Completions
depth). The rock formation to be drilled is classified as extremely hard, and it is
anticipated that 10 ft/hr will be the maximum possible drilling rate. The mud weight
is to be 16.2 lb/gal. The drilling rig has a National Supply Company, triplex mud
pump Model 10-P-130 available. The details of this pump are given in Table 4112
(also see the section titled “Mud Pumps” for more details). Because this is a
deviation control run, the shorter two motor section turbine motor will be used.
Determine the appropriate circulation flowrate to be used for the diamond
bit, turbine motor combination and the appropriate liner size to be used in the
triplex pump. Also, prepare the turbine motor performance graph for the chosen
circulation flowrate. Determine the total flow area for the diamond bit.
Bit Pressure LOSS. To obtain the optimum circulation flowrate for the diamond
bit, turbine motor combination, it will be necessary to consider the bit and the
turbine motor performance at various circulation flowrates: 200, 300, 400 and
500 gal/min.
Since the rock formation to be drilled is classified as extremely hard, 1.5
hydraulic horsepower per square inch of bit area will be used as bit cleaning
and cooling requirement [87]. The projected bottomhole area of the bit 4 (hZ) is
R
A,, = -(8.5)‘
4
= 56.7 in.‘
For a circulation flowrate of 200 gal/min, the hydraulic horsepower for the bit
HPb (hp) is
HP, = 1.5 (56.7)
= 85.05
The pressure drop across the bit Ap ( si) to produce this hydraulic horsepower
b p.
at a circulation flowrate of 200 gal/min is
*Pb =
85.05( 1,714)
200
= 729 psi
Table 4-112
Triplex Mud Pump, Model 10-P-13 National Supply Company, Example 2
input Horsepower 1300, Maximum Strokes per Minute, 140 Length of Stroke, 10 Inches
Liner Size (inches)
5% 5 % 5Y4 6 6%
Output per Stroke (gals) 2.81 3.08 3.37 3.67 3.98
Maximum Pressure (psi) 5095 4645 4250 3900 3595