Abstract: Most coalbed gas fields in China have poor physical properties，permeability is generally less than 1. 0 mD，and the well pattern and well spacing is too large，which leads to difficulties in regional coordinated depressurization and production of gas well is low. Infill adjustment of the horizontal well is one of the effective key technologies to solve the production increase of coalbed gas wells. Taking Shizhuang south block as the research object，this paper evaluated the rationality of well pattern and well spacing in this area using well test interference and numerical simulation，optimized the potential area of horizontal well infilling according to reservoir geological parameters，designed the adjustment scheme of horizontal well infilling，and applied it. The results showed that after the infill adjustment of horizontal wells，the distance between coalbed methane（CBM） wells was shortened， effective communication between regional gas wells was formed，and regional depressurization was formed. The stable daily gas production of horizontal wells was 3 600 m³ ，which was 2. 5 times of surrounding gas wells. The average production increase of single wells in surrounding gas wells was 300 m³/d，and remarkable results were achieved.

Key words: well test interference, numerical simulation, pressure propagation, horizontal well infill, potential area