Abstract: The single-casing segmented-fracturing horizontal well has currently become the main development well type in the Zhengzhuang block. However, it is currently characterized by large differences in single-well production, rapid local production decline, and low ultimate recovery rate, which poses a great challenge to the continuous development and adjustment of the old area. Based on the development practice of horizontal wells in the Zhengzhuang block, combined with geological features, engineering parameters, and the drainage and production laws of horizontal wells, the ultimate recoverable reserves of coalbed methane were predicted through numerical simulation software. The influencing factors of single-well estimated ultimate recovery (EUR) were analyzed from multiple aspects such as geology, engineering, and drainage and production. On this basis, targeted technical countermeasures to improve recovery rate were proposed. The results show that EUR of the early horizontal wells in the Zhengzhuang block range from 32 to 38.04 million cubic meters, with a single-well recovery rate of 1% to 62%, and a distribution pattern of high in the south and low in the north on the plane. The recovery rate of coalbed methane wells is comprehensively controlled by geological conditions, fracturing scale, drainage and production methods, etc. Among the geological conditions, the length of high-quality coal seam sections, the orientation of principal stress, and the coal body structure have a significant impact on EUR and recovery rate: the longer the high-quality coal seam section, the larger the controlled reserves of the well, and the recovery rate shows a trend of increasing first and then decreasing, with an optimal horizontal section length that can maximize the single-well recovery rate and cost-effectiveness; when the wellbore trajectory is approximately perpendicular to the principal stress direction, the single-well EUR is significantly higher than that of horizontal wells parallel to the principal stress direction, which is conducive to maximizing the controlled reserves of fractures. In the coal body structure's fragmented area, the greater the coal mud output, the more likely the coal powder is to block the production fracture channels, causing rapid production decline and a decrease in the single-well recovery rate. The fracturing scale has a significant control effect on the middle and deep horizontal wells in the area. The EUR of large-scale and high-volume fracturing horizontal wells in the same well group (25 million cubic meters) is significantly higher than that of medium and small-scale fracturing horizontal wells (10 to 17 million cubic meters). Excessive drainage and production speed can cause reservoir stress sensitivity, rapid production decline, and a 20.6% reduction in single-well EUR. Based on the geological conditions, ultimate recoverable reserves, recovery rate, and coal powder output degree of horizontal wells, the horizontal wells in the area are classified into four types: high recovery wells, new wells in low-permeability and high-stress areas, low-efficiency wells with coal powder and sand blockage, and wells with unreasonable drainage and production systems. For different types, differentiated technical countermeasures are proposed to achieve the goal of slowing down the decline and improving the ultimate recovery rate. For new wells in low-permeability and high-stress areas, large-scale fracturing is adopted to expand the range of fracturing modification and effectively modify the reservoir, increasing the recovery rate. The initial annual decline rate of horizontal wells is reduced by 12.4%, and the single-well EUR is generally increased to over 25 million cubic meters, with a recovery rate increase of 6% to 21%. For low-efficiency wells with coal powder and sand blockage caused by the fragmentation of the coal body structure, foam well washing and nitrogen gas permeability enhancement techniques are used to remove wellbore blockages and restore single-well productivity, increasing the single-well EUR by more than 5 million cubic meters and the single-well recovery rate by 10.6%. For production wells with unreasonable drainage and production systems that cannot fully release productivity, the drainage and production systems are timely optimized based on the material balance method of flowing substances to avoid rapid production increase causing stress sensitivity and reducing the ultimate recoverable reserves.