OPTIMIZATION OF DIAMOND CORE BIT PERFORMANCE UTILIZING HIGH ROTARY SPEED IN DRILLING LIMESTONE ROCKS | ||||
| JES. Journal of Engineering Sciences | ||||
| Article 10, Volume 38, No 6, November and December 2010, Page 1531-1543 PDF (517.89 K) | ||||
| Document Type: Research Paper | ||||
| DOI: 10.21608/jesaun.2010.125575 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| Mohamed A. Sayed; Gamal Y. Boghdady | ||||
| Professor at the Mining and Metallurgical Engineering Department, Faculty of Engineering, Assiut University, Assiut 71516, Egypt | ||||
| Abstract | ||||
| The principal factors that require in predicting drilling rates are the operating parameters of the drill bits and the penetrated rock characteristics. The effect of some mechanical and geological parameters on the penetration rate during drilling limestone rocks has been previously carried out by using a low rotary speed of 400 rpm. In this work, the drilling trails were carried out on the same rocks and by using the same machine and bit at high rotary speed of approximately 1200 rpm. A fixed laboratory-diamond drilling machine was used to drill three types of limestone rocks utilizing rotational speed of 1200 rpm, and over a range of weights on bit (WOB). Operating parameters of the drill bit such as WOB, rate of penetration (ROP), torque and drilling specific energy (SE) were continuously monitored during the drilling trials. The effects of these parameters on the performance of the bit were examined. Relationships between WOB and both ROP, and SE were also described and the relationship between ROP and SE was also given. The obtained results were compared with that obtained by using a low rotary speed of 400 rpm. Increasing the rotary speed from 400 rpm to 1200 rpm increases the rate of penetration 3 times for Fresh limestone at the optimum weight on bit of 105 kg and this leads to decrease the specific energy. To obtain ROP of 0.5 cm/min as an example, the drilling machine needs S.E in Non-Fresh Limestone 3 times that for Fresh limestone and 2 times for Bedded limestone. | ||||
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