空气钻井燃爆灭火阀的研制及其在普光气田的应用

空气钻井有效地提高了机械钻速、缩短了钻井周期，但其最大的问题之一就是井下燃爆问题。为了解决空气钻井在钻遇油气层时，发生井下燃爆，造成埋钻具、井眼报废等复杂情况，基于阻断氧气使火熄灭的思路研制出了一种低熔点合金制造的井下工具--空气钻井燃爆灭火阀。该灭火阀连接在钻头上方，一旦环空着火爆炸，温度升高，低熔点合金就会熔化，关闭阀门，切断气源使火熄灭，制止事态的进一步扩大；还开发了空气钻井防燃爆监测系统，可实时监测返出气体组分的变化和井下燃爆隐患，以确保空气钻井安全、实现快速钻进。

Development of downhole explosion prevention sub for air drilling: A case study in the Puguang gas field

Air drilling can improve the ROP and shorten the drilling cycle effectively, but downhole explosion is the fatality of its good performance. To avoid loss of drilling tools and even well abandonment due to downhole fire or explosion during air drilling in pay zones, we developed a novel downhole fire or explosion prevention sub, a kind of downhole tool made of low melting point alloy, designed to shield off oxygen so as to put out fires. This sub is connected to the upper part of dill bit. Once downhole fire or explosion occurs, the annular temperature would increase, so the valve in this sub will shut off when temperature is higher than the melting point, in this case, the downhole fire will be prevented without delay. In addition, we developed a borehole explosion monitoring system for air drilling to monitor any minor changes of gas components or any hidden danger in real time, thus, to benefit the air drilling.