元坝272H井超深硬地层侧钻技术

Ultra-Deep Sidetracking in Well Yuanba 272H

针对元坝272H井侧钻井段调整余地小、侧钻地层高温高压、岩石可钻性差、井眼尺寸小等实际情况,在深入分析侧钻技术难点的基础上,优选了侧钻方式、侧钻点和钻具组合,确定了侧钻技术措施:基于长定向井段的施工安全,选择了常规裸眼侧钻方式;因为侧钻点与靶点垂距仅为70.00m,为减小增斜段井眼的全角变化率,选择出套管1.00～5.00m处为侧钻点;因为侧钻点处于硬地层,为增大侧钻力,优选了"牙轮钻头+直螺杆+2.75°弯接头"钻具组合;另外,确定了下切侧钻、延长控时钻进时间、合理侧钻方向、加强施工监测和保证钻井液性能等施工措施。该系列技术措施在元坝272H井小井眼侧钻施工中进行了应用,井眼轨迹数据、返砂新岩屑质量分数及钻井参数显示,在井深6 672.30m处新老井眼完全分离,应用获得成功。该超深硬地层侧钻施工技术的应用成功,对同类井的侧钻作业具有借鉴意义。

Considering the situation of Well Yunaba 272H, such as smaller adjustment space, HTHP, poor drill ability and smaller hole diameter of sidetracking intervals, the sidetracking method, sidetracking point and bottom-hole assembly were selected. Relevant technical measures were taken, including conven- tional open hole sidetracking method for the purpose of safety in long directional section. As the sidetrack- ing point is deeper than 6,600 m,and the over all angle changes beyond the designed rate, the sidetracking point was selected at 1.00-5.00 m beneath the casing shoe. Due to the sidetracking point retained in hard rocks,the bottomhole assembly was determined as＂roller bit＋ straight PDM＋ 2. 75° bending sub＂to in- crease the sidetracking force. Additionally,certain operation measures were taken, such as suspended lower sidetracking, reasonable control over sidetracking speed and direction, strengthening the monitoring of op- eration,and ensuring drilling fluid performance, etc. These measures were successfully applied in Well Yuanba 272H, the well path, concentration of cuttings and drilling parameters show that new and old holes were completely separated at the depth of 6 672.30 m. This success is significant for sidetracking in similar wells.