Method to Identify Perforation Locations for Fracturing Deep and Tight Gas Reservoirs

Fracture initiation has been a challenging issue for fracturing deep and tight gas reservoirs, which generally requires a high breakdown pressure for hydraulic fracturing treatment. In this situation, fluid injection has to terminate at the very beginning. Toward predicting and solving this issue, a novel fracturing system for deep and tight sandstone gas reservoirs was developed. Other issues related to perforation cluster layout design will be discussed as well. The key components of the fracturing system and some criterion will be introduced in this paper, which can be used to identify the ideal perforation locations along the landing part and select the right perforation strategy accordingly. The main components of the fracturing system include: (1) Evaluating the log-based diagenetic rock typing and flow index; (2) 1D mechanical earth model; (3) calculating the breakdown pressure envelope along the well trajectory of the landing part; (4) calculating the optimal perforation directions along the landing part; (5) select the first set of perforation locations based on the log-based diagenetic rock typing and flow index; (5) narrow the first set of perforation locations to a second set of perforation locations based on the breakdown pressure envelope; and (6) compare the breakdown pressure envelope of the second set of perforation locations to a maximum downhole pressure the used wellhead can safely provide to determine a perforation strategy. The computational framework to calculate the breakdown pressure envelope and optimal perforation directions is applicable to arbitrary well trajectory. The fracturing system has been used to provide pre-fracking support for wells that landed in deep and tight sandstone reservoirs, which can assist in selecting locations with good rock typing and relatively low breakdown pressure. Also, it can indicate whether oriented perforation should be used. By taking these efforts and procedures, the fracturing success rate for deep and tight gas reservoirs can be improved, which has been verified in practice. Example studies from the field will be provided to demonstrate the fracturing system's performance and applicability.