Optimization and Field Application of Secondary Stimulation Technologies for Coalbed Methane Wells in Hancheng Block

The productivity of the coalbed methane (CBM) wells in Hancheng Block has not been fully exploited, resulting in a problem of failed stable and high production goals over the long term. To further optimize secondary stimulation technologies for coal reservoirs, stimulation of low-productivity CBM wells, and increase production of single CBM well, the geological characteristics of this block were analyzed, and the causes of the low production in the test wells after conventional secondary fracturing were explored. The main objectives of this research targeted the technical defects and difficulties during secondary stimulation, and solving the problem of “pulverized coal plugging fractures and limited propagation distance of new fractures.” Composite secondary stimulation technologies of “acidizing + temporary plugging” were developed and tested in the field in three wells. The results showed that after the composite secondary stimulation technologies were applied, the average gas production of Test Well J4 reached 3 765.6 m³/d, indicating that a significant production increase was achieved and that the stimulated fracture volume was satisfactory. In addition, the production capacity of Test Wells J5 and J6 recovered and demonstrated great production potential. With a favorable application effect in low-productivity CBM wells, the proposed composite secondary stimulation technologies can provide a technical reference for the stimulation of old CBM wells under similar geological conditions.