九龙山某井气体钻井技术及事故处理实践

Gas Drilling Technology in a Well and the Practice of Accident Treatment

摘要:

九龙山地区上部地层存在井漏、垮塌的可能，中部地层研磨性强、可钻性极差，下部地层存在多产层多压力系统并可能会钻遇异常高压。为了应对异常情况、缩短钻井周期、节约处理成本，龙某井设计从350～2000 m使用气体钻井。空气钻井钻至1170.28 m后地层出气，甲烷浓度超过6%，后改用氮气钻进，钻至1868 m时出现井壁垮塌和钻具阻卡，随后停止气体钻进。记录了钻进过程中返出主要气体的浓度变化情况和异常情况处理措施，实践表明，气体钻井在防止井漏、钻遇地层出气（不含H2S）、异常压力等复杂情况具有常规钻井无法比拟的优势。

Abstract:

There is possibility of circulation loss and collapse in the upper stratum of Jiulongshan region, strong abrasivity and extremely poor drillability in the middle stratum, and multiple field and pressure system in the lower stratum. In order to cope with the abnormal situation, this well is designed to use gas drilling. The stratum is gassing when air drilling was dilled to 1170.28m. Then switch to nitrogen drilling, but when drilled to 1868m, it is wellface collapsed and drill stem blocked and sticking. At last it must finish the gas drilling. The paper records a main gas concentration changes and the handing measures of the abnormal condition during the drilling process, and provides some experiences to gas drilling crews dealing with abnormal condition. In conclusion, gas drilling have more advantage than conventional drilling in preventing circulation loss, stratum gassing without H2S, and abnormal pressure.