应用U型井开采倾斜构造煤层气的钻采技术研究

倾斜高陡构造煤层气钻井的共性是井斜难以控制,而且这类储层分布较广,潜力巨大。根据霍林河煤层气构造地质条件,地层倾角较大,主力煤层厚度大,渗透率较高,又属于典型的低煤阶煤层气,易于实施U型斜井钻采工艺。U型斜井钻采工艺特殊,利用定向斜井与其远端的直井在井下连通,建立煤层流体循环系统。为了保护煤层,煤层钻进过程中要采用环空充气欠平衡钻井工艺。采气时要选用排量范围广、成本低、耐砂能力强的螺杆泵,提高排采效率;U型斜井能够充分发挥倾斜地层流体势能和各井的优势,能够提高排水和采气效率。结合霍林河煤层气钻采,探讨了U型煤层气井钻完井工艺及采气工艺。

Study on Drilling and Extraction Technologies for High Steep Structure Coalbed Methane with U-shape Slant Well

The well inclination is difficult to control for high steep structure CBM drilling,and such reservoir spreads extensively and has a huge potential in China.According to the conditions of coal seam structure in Huolinhe basin,coalbed methane with large inclination,large thickness and high permeability is classic low coal rank and is easy to implement the process of drilling and extraction with U-shape slant well.This technology is to build a kind of special fluid circulatory system in coal seam by intersection of directional deviated well and a vertical well.Annular gas under-balanced drilling technology has been adopted in the drilling course in order to protect coal seam.Screw pump with large delivery capacity,low cost and strong sand resisting should be selected to improve production efficiency.U-shape slant well can take full advantages of fluid potential of coal seam and every well and improve efficiency of dewatering and gas producing.The paper discussed the drilling and completing technology of U-shape coalbed methane well and gas production technology according to the drilling and extraction in Huolinhe.