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Unformatted text preview: al ROP reduces when the bit hydraulic contribution increases, for the same WOB. It also shows that the
incremental ROP increases with WOB when the bit hydraulic contribution is kept constant. These finding are explained on
the next paragraph using one example.
By combining Figs. 9 and 10 the effect of increasing both the mechanical and hydraulic energy (instead of increasing only
the mechanical energy) on ROP is revealed (Fig 11). When moving from point 1 to point 2, a 35% increment on ROP is
obtained. In this case, only the mechanical energy is increased. WOB is increased from 30,000 lb to 40,000 lb while keeping
the HSI constant at 2.0 hp/in2. In doing so, the bit hydraulic contribution decreases from 13.5% to 9.2%. One the other hand,
by moving from point 1 to 3, a 57% increment on ROP is achieved (22% more than the previous case). In this case, both
mechanical and hydraulic energy are increased at the same time. WOB is increased again from 30,000 lb to 40,000 lb, but
this time the bit hydr...
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- Spring '13