SPE Drilling & Completion
Volume 25, Number 2, June 2010, pp. 187-192

SPE-130377-PA

Real-Time Downhole Monitoring and Logging Reduced Mud Loss Drastically for High-Pressure Gas Wells in Tarim Basin, China

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DOI  More information 10.2118/130377-PA http://dx.doi.org/10.2118/130377-PA

Citation

  • Wang, S.-C., Zheng, X., Jiang, Y., Tang, J., Zheng, C.J., Yu, J., Wu, B., and Fan, H.-H. 2010. Real-Time Downhole Monitoring and Logging Reduced Mud Loss Drastically for High-Pressure Gas Wells in Tarim Basin, China. SPE Drill & Compl  25 (2): 187-192. SPE-130377-PA. doi: 10.2118/130377-PA.

Discipline Categories

  • 1.2.6 Well Control, Blowout Flow Modeling
  • 1.3.1 Wellbore Integrity/Geomechanics
  • 2 Health, Safety, Security, Environment and Social Responsibility

Keywords

  • mud loss, overpressure, well control, real time, gas well

Summary

This paper describes a real-time case study to prevent mud loss and blowouts while drilling a high-pressure gas well in Tarim basin, China. The complex geological structure, high tectonic stresses, and overpressured- and fractured-reservoir formations in the field present a huge challenge to drilling. Of the seven wells drilled in the field in 2005, two did not reach target depths, four experienced huge mud loss, and the other experienced a blowout, resulting in lost control of the well. In early 2006, PetroChina teamed up with Schlumberger and Petroleum University of China to form a collaborative technical group to develop a better understanding of mud-loss and blowout mechanisms. The key component of the study was to establish a mechanical Earth model (MEM) based on offset well data before drilling, update the model using downhole monitoring and logging data during drilling, and predict a safe mud-weight window in real time.

Real-time prediction of a safe mud-weight window with annular-pressure monitoring helped ensure that downhole annular pressure was maintained within the safe mud-weight window during drilling and tripping. The study resulted in a ×17 reduction in mud loss and ×10 reduction in total nonproductive time (NPT), which is mainly because of mud-loss reduction and elimination of an extra casing. A better understanding of mud-loss/blowout mechanisms was achieved, and guidelines for preventing mud loss/blowouts specific for this gas field were developed.

© 2009. Society of Petroleum Engineers

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History

  • Original manuscript received: 4 August 2008
  • Meeting paper published: 3 December 2008
  • Revised manuscript received: 28 January 2009
  • Manuscript approved: 10 February 2009
  • Published online: 17 November 2009
  • Version of record: 14 June 2010