川东地区浅层复杂井段气体钻井应用实践

Application of Gas Drilling to Shallow and Complex Well Sections, Eastern Sichuan Basin

川东高陡构造区裂缝溶洞发育,且地层压力梯度较低,在浅层至中层用清水钻进,一般都有恶性井漏发生。很多井漏层都含有流动水层,大大加大了堵漏的难度。由于井下及地面条件限制,部分井难以实施清水强钻,采用气体(雾化、充气)钻井,地层产水,诱发井壁垮塌,卡钻风险高,钻井难度大。针对上述钻井难点,深入分析部分区域上部漏失地层气体(雾化、充气)钻井情况,总结了区域钻井方式优选、气体参数推荐、水泥堵漏(补壁)技术,提出了进一步开展各区域浅表层复杂井段安全快速钻井的建议。

In high-steep structural belts, eastern Sichuan Basin, both fractures and caves are very developed in some formations with lower pressure gradient. Especially, in the shallow to middle formations, vicious lost circulation often happens during a clean water drilling. Moreover, it's more difficult to implement a leakage protection due to movable waters always found in lost-circulation layers. So, the clean water drilling is not available. However, other gas drilling methods such as misting and aeration drilling easily lead to wellbore collapse or high sticking risk because of formation water. In this study, gas drilling for leakage formations is analyzed,and drilling methods are optimized, gas parameters are recommended, and a technology of leakage protection by slurry is presented.Finally, a suggestion on implementing a safe and fast drilling in shallow to subsurface and complex well sections is made.