煤矿瓦斯抽放井一次成井工艺及技术效果

煤矿瓦斯抽放井要求垂直精度高、井径大，通常采用常规钻探工艺时，需进行3-4次扩孔才能达到最终孔径，施工时间较长，钻进效率较低。此次在端氏煤矿施工的大口径瓦斯抽放井，采用了的一次成井钻进技术及工艺方法，钻进口径达到φ660mm，选用了江汉735型和715型系列镶齿牙轮钻头，采用塔式加重钻具控制并保证了钻井的重直度，采用密度较大的化学泥浆和保持大泵量排渣，避免了井底牙轮钻头的重复破碎，确保了钻进效果。与传统的扩孔工艺相比，缩短了施工周期，成井质量高，提高了钻进效率，降低了钻进成本。

Coalmine Gas Drainage Well Simultaneous Completion Process and Technical Effects

The coalmine gas drainage well requires high perpendicularity and large diameter. When the traditional drilling technique is used, the final diameter can only be arrived until 3-4 times of reaming, thus long construction time limit and low drilling efficiency. The large φ660mm diameter gas drainage well constructed in the Duanshi coalmine, used simultaneous completion process drilling technique with Jianghan 735 and 715 series inserted roller bits. The turret type weighted drilling tool controls well perpendicularity, higher density chemical mud and larger pump volume cutting removal can avoid bottom roller bit repeated crushing and ensure drilling effect. In comparison to traditional reaming technology, the method shortens construction period, ensures well completion quality, improves drilling efficiency and reduces drilling cost.