The development characteristics and main control factors of the open-hole multi-branch CBM horizontal wells

The overall development performance of open-hole multi-branch horizontal wells in Fanzhuang-Zhengzhuang block is not satisfactory because of the high proportion of low-production wells and significant difference in the production among different wells. So the main controlling factors should be researched in order to improve the development performance of open-hole multi-branch horizontal wells. Based on the development practice over 10 years in this area, this paper divides the wells into three types according to different production characteristics by statistics and regression, such as continuous high production type, high production at beginning and low production later type and continuous low production type. Studies show that gas contents, permeability, slight geo-structure and coal body structure are key geological factors determining the production and the stable production period of open-hole multi-branch horizontal wells. Permeability determines whether these wells can reach high production or not and slight geo-structure and coal body structure determine the last time for high production under the same gas content condition. The low gas contents, low permeability, collapse of the multi-branch during drilling and the pollution of drilling fluids are main causes for the continuous low production of these open-hole multi-branch horizontal wells. The results of this paper improve the technology and boost the production of open-hole multi- branch horizontal wells in Fanzhuang-Zhengzhuang block.