Prediction of sonic flow conditions at drill bit nozzles to minimize complications in UBD

B. Guo, A. Ghalambor, A. S. Al-Bemani

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Sonic flow of liquid-gas mixtures at drill bit nozzles is believed to be responsible for some complications in underbalanced drilling (UBD), owing to pressure discontinuity and temperature drop at the nozzles. It is vitally important to avoid this flow condition in UBD by selecting optimal nozzle size and fluid flow rates. However, there is no method that can be used for prediction of the sonic flow condition. This paper introduces an analytical model for calculating the critical pressure ratio when two-phase sonic flow occurs. The analytical model can be coded in a spreadsheet. The critical pressure ratio charts are also provided for field engineers. Use of the model and charts in selection of bit nozzle size and two-phase flow rates will reduce complications in UBD.

Original languageEnglish
Title of host publicationCanadian International Petroleum Conference 2002, CIPC 2002
PublisherPetroleum Society of Canada (PETSOC)
ISBN (Print)9781613991091
Publication statusPublished - 2002
Externally publishedYes
EventCanadian International Petroleum Conference 2002, CIPC 2002 - Calgary, Canada
Duration: Jun 11 2002Jun 13 2002

Publication series

NameCanadian International Petroleum Conference 2002, CIPC 2002


OtherCanadian International Petroleum Conference 2002, CIPC 2002

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Energy Engineering and Power Technology

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