Key Drilling Technologies of Infill Wells in the Fuling Shale Gas Field

Infill wells in the Fuling Shale Gas Field are mostly located in the shale gas fracturing area with dense well pattern, resulting in many drilling technical problems, such as complex and frequent overflows and leakages, difficulty in determining reasonable drilling fluid density window, borehole collapse and sticking caused by fracturing fluid intrusion, and high difficulty in designing borehole trajectory to avoid fracturing interference, etc. To solve the above problems, technical research has been carried out from the perspectives of establishing a formation pore pressure calculation model for fracture zones, reasonable drilling fluid density window design, anti-fracturing interference borehole trajectory design, leakage prevention and plugging, and the prevention and control of simultaneous overflow and leakage in infill wells, etc., forming the key drilling technology suitable for infill wells in the Jiaoshiba main block of Fuling. The key technology has been applied in 31 wells in the Fuling Shale Gas Field, with an average horizontal interval of 1 933.25 m, an average drilling cycle of 52.38 days, and an average ROP of 10.31 m/h. Compared with previous infill evaluation wells, the ROP was increased by 15.3%, and the drilling cycle was shortened by 10.7%. The key drilling technology for infill wells in the Fuling Shale Gas Field provided technical support for the phase II productivity construction of the Fuling Shale Gas Field, and also provided technical references for the development of other shale gas fields.