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78 Part I Liquid Drilling Systems

Illustrative Example 3.4 (Continued )
Table 3.6 Specifications of TSC WF700 Triplex Pumps
Pinion RPM 30 60 160 260 360 460 560 660 760
Pinion lb/ft 4912
Performance
Characteristics Pinion HP 28 56 150 243 337 430 524 617 711
Piston
Diameter Pressure Speed
(in) (psi) (spm) 6 12 32 51 71 91 111 131 150
4 5,253
8.2 16.5 43.9 71.4 98.9 126 154 181 209
4.5 4,151
10.4 20.9 55.6 90.4 125 160 195 229 264
5 3,362
Flow rate 12.9 25.7 68.7 112 155 197 240 283 326
5.5 2,779 (gpm) 15.6 31.2 83.1 135 187 239 291 343 395
6 2,335 18.5 37.1 98.9 161 223 284 346 408 470
6.5 1,989 21.8 43.5 116 189 261 334 406 479 551
7 1,715 25.2 50.5 135 219 303 387 471 555 639

Equation (3.13) gives horsepower for each pump:
2
pd lN
HP =
168,067e m
2
= ð3461Þð4:5Þ ð8:5Þð107Þ
168,067ð0:90Þ
= 421 hp

Therefore, the total input horsepower needed from the prime movers is
(2)(421) = 842 hp. The safety factor in horsepower is (700)/(421) = 1.67.
According to Eq. (3.16), the maximum allowable pump pressure is calculated
to be 5,862 psi (40 MPa). However, the manufacturer-recommended maximum
working pressure for the 4.5-in. liner is 4,151 psi. The safety factor in pressure
is (4,151)/(3,461) = 1.2.

SUMMARY

This chapter presented theory and procedures for selecting mud
pumps. Extreme borehole geometries and mud properties should be con-
sidered for calculating the minimum required flow rate, pressure, and
horsepower. Safety factors should be applied.