Influencing Factor and Frac-Hit Prevention Countermeasures in Fractured Shale Gas Reservoirs

The abundant natural fractures in shale gas reservoirs are not only beneficial to improve the productivity of gas wells, but also increase the probability of frac hits between infill wells and parent wells, Which reduces gas well production and restricts the efficient development of shale gas. Aiming at the problem of frac hits existing in fractured shale gas reservoirs in WY area, this paper firstly introduces the common shale frac hits channel identification method. Based on the study of block production dynamics and fracture development, maximum likelihood chart method is used as the primary method for qualitative identification of fracture channeling, and the criterion for the type of frac hits channel is established. Combined with five correlation analysis methods, the main geological engineering key factors of fracture - dominated frac hits channel are determined, so as to explore the corresponding feasible frac hit prevention countermeasures. The research shows that the distribution and development of natural fractures are very important to the production after frac hits. Among them, the approach angle, the fracture linear density on the frac hits path and the horizontal in-situ stress difference are the main factors of natural fracture - dominated frac hits. The net pressure in fracture, horizontal stress difference and liquid strength are the main influencing factors of hydraulic fracture - dominated frac hits. By changing the amplitude of the corresponding key parameters, it is found that the activation difficulty coefficient of natural fractures fluctuates from −35.1% to 47.6%. The length of the hydraulic fracture fluctuates from −43.5% to 25.29%. Based on the two types of frac hits, the corresponding frac hits prevention countermeasures are proposed from different directions such as fracture risk assessment and path planning, production well pressurization and stress steering, and infill well fracturing parameter optimization. This paper not only provides a reference for exploring the formation mechanism of inter-well pressure channeling in fractured shale gas reservoirs, but also provides a theoretical basis for frac hits prevention countermeasures.