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Unformatted text preview: one can increase the ROP, the efficiency of the system reduces when nothing is done on
the hydraulic side.
DSE can be used to identify specific inefficient drilling situations such as, bit balling and friction-limiter. On the bit balling
case, the ROP decreases and the DSE increases steadily as the drilling progresses. New clean-bits can deliver similar ROP
and DSE values, even though they are run at different depth on the same formation. On the friction-limited situation, the
change on ROP and DSE values are drastic. The ROP trend jumps to lower values and the DSE trend shifts to higher values.
DSE also becomes very erratic.
= bit area, in.2
= rock confined compressive strength, psi
= bit diameter, in
= drilling Efficiency
= bit hydraulic power, hp
= mechanical specific energy, psi
MSEactual = actual mechanical specific energy, psi
MSEmin = minimum mechanical specific energy, psi
= rate of penetration, ft/hr
= revolutions per minutes, rpm
= specific energy, psi
= torque, ft-lbs
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- Spring '13