Scientia Iranica

Scientia Iranica

Pressure Drawdown Mechanism and Design Principle of Jet Pump Bit

Authors
State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
Abstract
Reducing the bottom hole differential pressure (BHDP) and so as to reduce the cuttings hold-down effect can significantly improve the rate of penetration (ROP). This paper analyzes the pressure drawdown mechanism of the jet pump bit, and then designs a novel annular jet pump bit. Using hybrid grid method, the key factors which affect the pressure drawdown capacity of the bit are discussed. The backflow below the reverse nozzle outlet is the main reason that reduces the pressure drawdown capacity of the jet pump bit. The design principle of the jet pump bit is given: the axial and radial angles are 150°-180° and 60°-75° respectively, the bit clearance should be kept below 3 mm, preferably using the vortex-jet flow combination pressure drawdown theory to reduce the bottom hole pressure, and the bit rotation speed should be as large as possible, which provide the theoretical guide for its development. 
Keywords

Volume 22, Issue 3 - Serial Number 3
Transactions on Mechanical Engineering (B)
June 2015
Pages 792-803

  • Receive Date 11 October 2014
  • Accept Date 27 July 2017