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Mud Pumps 65

Table 3.1 Rock Properties and Drilling Parameters at Different Hole Depths
Cuttings Cuttings Rate of Rotary Cuttings
Depth Density Sphericity Penetration Speed Concentration
ft m lb/ft 3 g/cc ball = 1 ft/hr m/hr rpm %
120 37 162 2.60 0.85 90 27.44 70 15
140 427 165 2.65 0.8 70 21.34 60 10
7,000 2,134 168 2.70 0.75 50 15.24 50 8
10,000 3,048 172 2.75 0.7 60 18.29 40 5

Table 3.2 Computer Spreadsheet Minimum Flow Rates.xls
Input Data U.S. Units SI Units
Cuttings specific gravity 2.6 water = 1
Particle sphericity 0.85 ball = 1
Drilling fluid viscosity 20 cp Pa-s
Drilling fluid density 9.2 ppg g/cc
Annulus OD 24 in mm
Annulus ID 6.625 in mm
Rate of penetration 90 ft/hr m/hr
Rotary speed 70 rpm rpm
Cuttings concentration 15% %

Solution
Cuttings equivalent diameter 0.26 in
A′ = 2:2954 − 2:2626 ψ + 4:4395 ψ − 2:9825 ψ 3 1.7481
2
2
B′ = −0:4193 − 1:9014 ψ + 3:3416 ψ − 2:0409 ψ 3 –0.8746
2
C′ = 0:1117 + 0:0553 ψ − 0:1468 ψ + 0:1145 ψ 3 0.1230
N ReP = 928ρ v sl d s 64
f
μ

2
^ 3.7215
f p = 10 A′ + B′ logðN ReP Þ + C′½logðN ReP ފ
s ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ρ − 7:48ρ

ν sl = 1:89 d s s f 0.58 ft/s
f p 7:48ρ f
2 2
A = πðd − d Þ 418 in 2
a
b
4
v tr = πd 2 ROP 0.18 ft/s
b
4C p A 3,600
0.76 ft/s
v min = v sl + v tr
q min = 3:1167v min A 990 gpm
(Continued )