川东北地区空气钻井燃爆分析与预防

Causes of air drilling downhole burst in Northeast Sichuan basin and preventive measures

空气钻井在钻遇油气层时,易发生井下燃爆,造成钻具被埋、井眼报废等复杂情况。为此,分析了井下燃爆发生的条件、方式、原因和燃爆机理,提出针对现场实际情况预防燃爆的措施,即加强对地层的认识,避免在油气层采用空气钻井或转换成雾化泡沫钻井,防止井下燃爆和卡钻的发生,保持井眼畅通防止滤饼圈的形成,利用UBD气体监测系统加强井下烃类气体的随钻监测以及采用防燃爆短节来及时发现和预防井下燃爆的发生,以保障空气钻井的顺利实施。

Downhole burst tends to occur when air drilling through payzones,which will result in downhole drilling tool failure and even well abandonment.This paper analyzed the condition,causes and mechanism of downhole burst.And preventive measures are suggested in order to perform air drilling successfully,including getting a good knowledge about the formation being drilled,no air drilling in payzones or converting to mist/foam drilling or mud drilling before the payzones,maintaining smooth wellbore to avoid filter cakes,keeping hydrocarbon gas monitoring while drilling to detect the burst in time,and using fire sub to prevent the downhole burst.