川西中浅层水平井钻井关键技术

Key Drilling Technologies Used in Middle to Shallow Horizontal Wells, Western Sichuan Basin

针对川西中浅层气藏储层埋深变化大,横向非均质性强,砂泥岩互层频繁,蒙脱石含量高易水化膨胀,导致机械钻速慢、钻井复杂频发等技术难题,采用优化井身结构及井眼轨迹技术、研发高性能聚胺仿油基钻井液体系、研制个性化PDC钻头及配套高效动力钻具技术,形成了川西中浅层水平井钻井关键技术。现场成功应用于150口井,解决了钻井效率低、安全钻井风险大等技术难题,单井平均机械钻速提高30.07%,平均钻井周期缩短16.93 d。

In western Sichuan Basin, most middle to shallow gas reservoirs are characterized by great variation in burial depth,strong lateral heterogeneity, sandstone interbedded frequently with mudstone, and rich smectite easily resulting in hydration and swelling. These characteristics may bring about many problems, such as low rate of penetration(ROP)and drilling complexity often occurred. So, some key technologies have been developed for the middle to shallow horizontal wells in western Sichuan Basin, including to optimize casing program and wellbore trajectory, to formulate polyamine imitation oil-based drilling fluids with high performance, and to work on special PDC bit and matching high-power drilling assembly. These technologies were applied to 150 gas wells and solved the problems of both low drilling efficiency and large risk in safe drilling. As a result, the average ROP was increased by30.07 % and the average drilling cycle was shortened by 16.93 d,individually.