Abstract:  The exploratory wells at Erdos basin have been drilled down to formations 4000 - 6000 deep, tight, highly aggressive and with poor drillability. The conventional drilling ROP was as low as 0. 3 ~ 0. 5 m/h, the bits were worn quickly. Considering these problems, study is made on nitrogen drilling regards its feasibility in drilling, ROP improvement and bit selection. And tests on Well T105, T91 at Erdos Basin have verified a single bit trip during the third spud-in by nitrogen drilling, the bit life obviously extended, ROP increased remarkably, a single bit footage of 200m, and average ROP of 2. 16 m /h in Changcheng formation, more than 4 times faster than the conventional drilling. Nitrogen drilling is a new means for ROP improvement.

Key words:  , natural gas exploration well, Changcheng System, nitrogen drilling, ROP improvement

摘要：  鄂尔多斯盆地布署的天然气风险探井完钻层位已进入年代古老的元古界、太古界地层，元古界长城系地层沉积年代远、地层埋藏深（4000～6000 ｍ），岩性致密、研磨性强、可钻性差，常规钻井机械钻速低（0.3～0.5 ｍ/ｈ）、钻头易磨损。文章针对长城系地层常规钻井存在的技术难题，开展了氮气钻井适应性分析、提速可行性分析、钻头优选等氮气钻井提速关键技术研究，并在鄂尔多斯盆地中西部天然气探井T105井、T91井长城系地层进行氮气钻井提速验证试验，实现了三开氮气钻井“一趟钻”作业，钻头寿命增加明显，提速效果显著，平均单只钻头进尺200 ｍ，长城系地层平均机械钻速2.16 ｍ/ｈ，同比常规钻井提速４倍以上，为长城系地层钻井提速提效提供了新

关键词:  , 天然气探井, 长城系, 氮气钻井, 提速