The mechanism and law of wellbore instability due to drill string impact in air drilling Online publication date: Tue, 30-Sep-2014
by Xiaohua Zhu; Weiji Liu; Qingyou Liu
International Journal of Oil, Gas and Coal Technology (IJOGCT), Vol. 8, No. 2, 2014
Abstract: Due to the low density and small damping factor of gas, drill string vibration in air drilling is much more violent than that in mud. Drill string impact on wellbore wall has a vital effect on wellbore stability in many cases. However, there are few researches about drill string impact on wellbore wall so far. In this paper, the calculation model of drill string impact on wellbore wall was established based on the experimental study. The instability law of wellbore was researched through numerical simulation under different conditions. In addition, authors researched the fragmentation mechanism of wellbore rock and derived the formulas of maximum pressure wellbore rock suffered when it began to fail. The results obtained in this paper can offer a great help on understanding both the law and the effect of drill string impact on wellbore wall for drilling engineers. [Received: November 3, 2012; Accepted: May 9, 2013]
Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.Complimentary Subscribers, Editors or Members of the Editorial Board of the International Journal of Oil, Gas and Coal Technology (IJOGCT):
Login with your Inderscience username and password:
Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.
If you still need assistance, please email subs@inderscience.com
Our Blog 
Follow us on Twitter 
Visit us on Facebook