SPE Drilling & Completion
Volume 27, Number 3, September 2012, pp. 355-362

Summary

On the basis of the analysis of the jet-modulating mechanism, a novel tool--a hydraulic-pulsed cavitating-jet generator (HPCJG)--is designed to further improve the rate of penetration (ROP). The HPCJG combines the advantages of a pulsed jet and a cavitating jet. When the drilling fluid flows through this tool, the fluid will be modulated to the pulsed and cavitating jet by application of the impellers and by entering into the self-resonant chamber. During this process, a pulsed cavitating jet is formed at the outlet of the bit nozzle. Because of jet pulsation, cavitating erosion, and the local negative-pressure effect, the cleaning efficiency of the well-bottom cuttings and the ROP will be improved. Laboratory and oilfield tests have indicated that the pulsed-pressure amplitude and the pressure drop of the generator increase with the increase of the flow rate. However, the frequency of the pressure pulsation is invariable in this process. This generator has been applied to more than 100 wells in eight oil fields throughout China. The results show that the maximum density of the test drilling fluid is 1.93 g/cm³, the maximum test-well depth is 6162 m, and the operation time of the generator is more than 230 hours (the maximum operation time recorded was more than 520 hours). Furthermore, the average ROP was increased by approximately 16.7% to 104.4%. In conclusion, the generator has the characteristics of a simple structure, has a long lifetime, is able to adapt well with existing drilling equipment, and can provide a safe and efficient drilling technique for deep wells.

© 2012. Society of Petroleum Engineers

View full textPDF ( 2,479 KB )

History

• Original manuscript received: 22 October 2011
• Revised manuscript received: 12 April 2012
• Manuscript approved: 27 April 2012
• Published online: 31 July 2012
• Version of record: 18 September 2012