兴古7-H208保留深层水平井导眼技术

水平井导眼填井侧钻是导眼实施的通常做法，但是在兴古7块，水平井导眼位置较深，导眼钻井周期长、钻井成本高，且导眼有一定产能或可另作他用。通过深层高钢级、厚壁套管开窗技术完善与精细施工控制、分支水平井井眼轨迹优化控制和分支井眼上固下裸眼内插管固井工艺的实施，在兴古7-H208井中的深层潜山油藏段内的?244.48 mm技术套管上开窗侧钻水平分支井眼，成功实现了深层导眼的保留。现场施工发现现有磨铣类工具对硬度8级以上地层的套管开窗适应性较差，最后通过取换造斜器、多次磨铣、钻头辅助破岩等方式得以完成。兴古7-H208井目的层埋深4000 m、导眼井段长875 m、钻井周期43 d，利用分支井保留水平井导眼技术节约了大量钻井费用，具有推广应用价值。

Using multilateral technique to retain deep horizontal pilot wellbore in Xinggu7-H208

Usually horizontal pilot wellbore is abandoned by cementing and sidetrack drilling. But in some deep blocks as Xinggu7 block, the construction time of the horizontal pilot wellbore is long and the cost is high, and the pilot wellbore is useful. In response to these factors, by the application of casing program optimization, window cutting and well construction management in deep impure granite formation that is cased with thick wall casings of high grade, well path control measures of multilateral horizontal borehole and up-casing down–barehole inside–inserting cementing technique, multilateral technique is successfully used in Xinggu7-H208 well to retain pilot well, and the sidetrack point is within ?244.48 mm casing in the buried hill reservoir. In the process of field implementation it is proved that the existing window milling tools are not suited to the formation whose hardness class is 8 or above, and the milling operation is completed by the renewal of whipstock, more trips of milling tools and secondary rock milling by bit. The target vertical depth of Xinggu7-H208 is 4000 m, and the pilot section is 875 m long whose drilling period is 43 days. As Xinggu7-H208, in some deep horizontal well using multilateral technique to retain pilot wellbore can avoid much waste of drilling cost, which is of promotion of value.