井下燃爆监测技术在气体钻井中的应用

气体钻井具有保护油气储层，机械钻速高，防漏、治漏效果好，防水敏垮塌，成本低等优点，因而应用越来越广泛。但天然气和原油等烃类物质与含氧气体混合后，在其混合浓度达到燃爆范围并有燃爆条件时，井下就可能出现燃爆，会造成井下复杂事故，影响气体钻井的安全性。尤其是近年来，气体钻井技术应用于非储层的长井段钻井提速，在缩短建井周期方面，钻遇小油气层的几率增大，发生井下燃爆的可能性也增加。利用井下燃爆监测技术，扩大气体钻井技术的应用范围、提高气体钻井效率是气体钻井技术的重要研究课题。基于对气体钻井过程中井下燃爆机理和方式的分析，采用西南石油大学欠平衡钻井技术研究室研发的多功能气体检测仪，对返出气体的成分、温度和压力的连续在线监测，可及时发现井下燃爆迹象，避免井下复杂事故的发生，为进一步完善气体钻井技术提供了有力的技术保证。

MONITOR AND CONTROL TECHNOLOGY OF DOWNHOLE EXPLOSION IN AIR DRILLING

Air drilling has been widely used because of its advantages including low cost, high ROP, good results in leakage resistance and guarding against water sensitivity and collapse. But on the other hand, air drilling adopted air as the circular medium and so hydrocarbons like natural gas and oil mixed with air will cause downhole explosion if only the mixture reaches the explosion limit under any possible explosive condition, which will certainly threaten the safety during operations of air drilling. Especially in recent years, air drilling technology has also been used to help increase the ROP and shorten the drilling circle especially in long well sections of non reservoirs, and the possibilities of both targeting small oil and gas formations and downhole explosions have become extremely high. To solve these problems, monitor and control technology of downhole explosions has already been an important issue in the study of improving efficiency and expanding the adaptability of air drilling. According to analysis on explosion mechanism and modes downhole in the process of air drilling, this study adopted a multi functional gas detection device, studied and developed by the Underbalanced Drilling Technology Research Lab of Southwest Petroleum University, to monitor on line the composition, temperature and pressure of the reversed gases, in this way any possible explosion signs under the well could be traced in time so that accidents could be prevented effectively and air drilling could be ensured as well by this unassailable technology.