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Mathematical Problems in Engineering
Volume 2016, Article ID 6032587, 10 pages
Research Article

An Explosive Range Model Based on the Gas Composition, Temperature, and Pressure during Air Drilling

1School of Oil & Natural Gas Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
2Shengli Petroleum Engineering Limited Company, SINOPEC, Hekou, Shandong 257000, China
3CCDC Drilling & Production Technology Research Institute, Guanghan, Sichuan 618300, China
4State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

Received 14 September 2015; Revised 21 December 2015; Accepted 24 December 2015

Academic Editor: Sergey A. Suslov

Copyright © 2016 Xiangyu Fan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Air drilling is low cost and effectively improves the penetration rate and causes minimal damage to liquid-sensitive pay zones. However, there is a potential downhole explosion when combustible gas mixed with drilling fluid reaches the combustible condition. In this paper, based on the underground combustion mechanism, an explosive range calculation model is established. This model couples the state equation and the empirical formula method, which considers the inert gas content, pressure, mixed gas component, and temperature. The result shows that increase of the inert gas content narrows the explosive range, while increase of the gas temperature and pressure improves the explosive range. A case in Chongqing, China, is used to validate the explosive range calculation model.