STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

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944 Drilling and Well Completions
Table 4-120
Resistance of Some Directional Toois or Components to Vibrations
Tool Low Frequencies High Frequencies
Azintac (1)
1 mm cm3 (5-50 Hz) 10 g (50-500 Hz)
Drill-director (2) 2 g (5-45 Hz) 5 g (45-400 Hz)
0-Flex accelerometer 25 9
Develco accelerometer
12.7 mm cm3 (20-40 Hz) 40 g (40-2000 Hz)
4-Gimbal gyroscope
2 g (1!I-200 Hz)
2-Axis gyroscope
5 g (10-300 Hz)
On-shore military specifications
14 g (50-2000 Hz)
(1) lust. Fr. du Pet. trademark
(2) Humphrey Inc. trademark
(The acceleration values correspond to maximum amplitudes.)
a
b
0' tl t
Figure 4-237. Theoretical deceleration variation during a shock or impact.
and the velocity at the beginning of the deceleration:
v = (::adt
= 0.66amt
For 500 g, 10 ms, we would have
d = 0.33 x 5000 x (0.01)2 = 0.16 m
v = 0.66 x 5000 x 0.01 = 33 m/s
assuming that 1 g = 10 m/s2.
Assuming the deceleration constant, as in the square approximation of Figure
4-237, we have a constant braking force, which is
F = ma = 0.66 mam (4-179)