苏53-78-71H井造斜段井眼轨迹防碰设计与控制

Anti-collision design and control of borehole trajectory of building-up section of Well Su 53-78-71H

苏53区块位于苏里格气田的西北部,每年钻成大量的水平井。该区块水平井大部分目的层设计在石盒子组气层,造斜段需要穿越石千峰组和石盒子组的泥岩,地层易漏和垮塌,导致井下施工困难。苏53-78-71H井位于该区块,造斜段先后侧钻4次,钻成5个井眼,特别是侧钻4井眼的防碰设计和施工难度大,在该区块尚属首次。从侧钻4井眼的侧钻位置选择、待钻井眼曲率设计、与原井眼的分离和其他井眼的防碰设计等方面进行了阐述、并在施工中从井眼轨迹控制、侧钻后定向段轨迹的防碰施工、入靶垂深的精确控制3方面进行了技术控制,保证了井下作业的安全施工,实现了精确入靶。

Located in northwestern part of the Sulige Gasfield, Block Su 53 has many horizontal wells drilled every year. The majority of horizontal wells drilled in the block target gas-bearing layers in Shihezi Formation, so their building-up sections often need to drill through mudstone in Shiqianfeng Formation and Shihezi Formation which are likely to have lost circulation and collapsing, with frequent downhole complications. Well Su 53-78-71 H drilled in the block contains 5 boreholes formed in 4 side-tracking operations in the building-up sections.The anti-collision design and implementation of the No. 4 sidetracked borehole is especially difficult, which is unprecedented in the block. In this paper, selection of optimal side-tracking position, design of borehole curvature to be drilled, separation from existing boreholes of No. 4 borehole, and anti-collision design of other boreholes have been reviewed. Borehole trajectory control, anti-collision measures in directional drilling sections after side-tracking and accurate control over vertical landing depth in target formations have been studied to ensure safety of downhole operation and accurate landing into the target formation.