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.