NOZZLE  UNDER AMBIENT PRESSURE

Yi Can

(Department of Petroleum Engineering, University of Petroleum(Huadong), Dongying 257061)

Li Gensheng

(Department of Petroleum and Gas Engineering, University of Petroleum(Beijing), Beijing 102249)

Zhang Dingguo

(Department of Petroleum Engineering, University of Petroleum(Huadong), Dongying 257061)

Abstract: It’s of great significance to research into the inception ability of nozzles and enhancement of their rock erosion effect to improve penetration rate of drilling deep wells. Self-resonant cavitating nozzle is designed with the principle based on the theory of fluid transients and hydro-acoustics. The lab investigation demonstrates that higher inception cavitation number and stronger cavitation effect under higher ambient pressure can be achieved in deeper bottom hole or under higher ambient pressure with self-resonant cavitating nozzle than the conventional cone-shaped nozzle, and the enhanced inception cavitation number can be as high as 1.67 while that of cone-shape nozzle is usually with 0.54 as the highest. Field tests are proved that the bit with self-resonating nozzles can significantly increase the footage of the bit, improving the penetration rate.

Key words: Nozzle  Cavitation inception   Cavitation jet  Drilling speed

CLC No: TK263.4

国家杰出青年科学基金(50125413)和中国石油天然气集团公司重点应用基础研究基金(03A20201)资助项目. Received 20040420, received in revised form 20040628