Fracturing Technology for a V-Shaped Horizontal Well Cluster in the Yanchuannan CBM Field

The Yanchuannan CBM Field is characterized by low single-well gas production, high production cost, and long payback period to recover the initial investment. In order to solve these problems, the V-shaped horizontal well cluster fracturing technology was studied for CBM development. Based on the statistics of fracture azimuths in the wells fractured in this CBM Field, it was possible to predict the fracture azimuths of wells to be fractured. Considering the coalbed thickness and the burial depth as well as inclined angle of horizontal section in two horizontal wells, the fracture positions and lengths were designed. After optimizing staged fracturing, fracturing fluids, proppant and fracturing parameters, the fracturing technology for V-shaped horizontal well cluster in the Yanchuannan CBM Field was established. This technology was applied in three V-shaped horizontal well clusters in the South Yanchuan CBM Field, cumulative fracturing were 29 stages, average fluid volume in each stage was 881 m3,the proppant volume added was 49.4 m3. As a result, the fracturing success ratio reached 90%, the average gas production of horizontal well was 6.18 times of that of directional well, and the input-output ratio was higher than that of the directional well. Field applications demonstrated that the fracturing technology for a V-shaped horizontal well cluster can enhance single-well CBM production, reduce the production cost, and shorten the payback period of investment.