牙轮-PDC混合钻头在迪北103井的应用试验

迪北103井是塔里木盆地库车坳陷东部依奇克里克构造带迪北斜坡的一口评价井,据邻井的实钻资料,预计该井在中新统吉迪克组、渐新统苏维依组、古近系库姆格列木群将钻遇砾石含量高、软硬交互频繁、可钻性差的地层,钻头选型困难,无论是牙轮钻头,还是PDC钻头,机械钻速和单只钻头进尺都很低。为此,在迪北103井的444.5mm井眼段尝试应用了牙轮-PDC混合钻头,该新型钻头由3个牙轮、3个PDC切削刀翼和钻头胎体构成,把PDC钻头优越的切削破岩机理及牙轮钻头的冲击破碎机理有机地结合在一起。试验从井深2 524m开始,一趟钻钻至2 866m,进尺342m,平均机械钻速1.70m/h,顺利钻穿吉迪克组—库姆格列木群组的复杂岩性段;与邻井(迪北104井)相同钻进井段相比,迪北103井钻头进尺提高了654%,机械钻速提高了157%,同时该井还刷新了444.5mm牙轮-PDC混合钻头单只进尺世界纪录。该钻头在迪北103井的成功应用为迪北区块钻井提速提供了有益的经验。

Pilot tests of a roller-PDC hybrid bit in Well Dibei 103, Tarim Basin

Well Dibei 103 is a test well in the Dibei Slope in the east of the Yiqiklik Structure in the Kuqa Depression of the Tarim Basin. Learning from the drilling data of adjacent wells, we know that this well will be drilled through the strata featured by high gravel content, frequent soft-hard rock interaction, and poor drillability in the Miocene Jidike Fm, the Oligocene Suweiyi Fm and the Paleogene Kumugeliemu Group. So it is difficult to select a proper bit because of the low ROP and footage by either a cone bit or a PDC bit. In view of this, a roller-PDC hybrid bit was tried in this case in the interval with a borehole diameter ofΦ444.5 mm in Well Dibei 103. Composed of three cones, three PDC cutting wings and a blank bit, this bit integrates the superior cutting mechanism of a PDC bit and the crushing mechanism of a cone bit. In a trial trip, this bit drilled smoothly through the Jidike-Kumugeliemu complex lithologic section with a footage of 342 m (from 2 524 m to 2 866 m deep downhole) and an average ROP of 1.70 m/h, which were increased by 654% and 157% respectively compared with those at the same drilled interval in Well Dibei 104. Moreover, this hybrid bit used in Well Dibei 103 refreshes its own single-penetration world record. This study provides valuable experiences in the ROP improvement for the drilling in this block.