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Unformatted text preview: owing the same pattern of
the previous bit (DSE increasing and ROP decreasing). Both bits are efficient at the beginning with high ROP and low DSE,
but their performance becomes inefficient as the drilling operations progress. The “efficient-drilling” trend is revealed on the
DSE vs. depth plot by drawing a straight-line across the efficient drilling sections. This “efficient-drilling” trend should be
related with the rock strength.
Fig. 13 shows the drilling parameters (ROP, WOB, RPM, torque, and HSI) for the same section included (from 2,200 ft to
6,000 ft) on Fig. 12. For the first bit, WOB is increased from 20,000 lb to 60,000 lbs; RPM varies from 120 rpm to 175 rpm;
torque changes from 4,000 ft-lbs to 8,000 ft-lb; and HSI varies from 1.4 hp/in2 to 2.6 hp/in2. Except by a small increase on
torque, no major changes on the drilling parameters (WOB, and RPM) are observed at the beginning of the second bit. Its
conditions are similar to the drilling parameters used at the starting of the first bit.
The fact that the second bit starts with an ROP four times grater than the final ROP for the first one tha...
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This note was uploaded on 01/31/2014 for the course MOGE 9114 taught by Professor Thomod during the Spring '13 term at Memorial University.
- Spring '13