Abstract: The Leikoupo Formation gas reservoir in the western Sichuan gas field is mainly developed with the “ultra-long openhole + liner completion + fixed-point diversion acid fracturing” method. The correct of the acid fracturing control range within the high-quality reservoir in the planar direction and the effective control of sweet spot reservoirs are key factors in enhancing the stimulation effectiveness of the ultra-long open-hole sections. To address these issues, the study optimizes the fracture control range for different reservoir types through production simulations and identifies the impact of reservoir heterogeneity on the fracture control range. A numerical simulation model is established, which couples acid fluid flow-reaction, pressure changes, wormhole growth, and hydraulic fracture propagation. This model is used to optimize the acid injection location, injection parameters, and timing of temporary plugging. The research findings indicate that the optimal fracture spacing within the high-quality reservoir should be 6180 m, and a thickness of the tight band >40 m affects the fracture control range. The maximum effective stimulation range within the wellbore is determined to be 264.6 m, and temporary plugging methods need to be employed to regulate acid absorption profiles during sweet spot dispersion. The study recommends using half of the acid volume for the initial stage of temporary plugging, and for the subsequent stage, it suggests post-plugging after the first stage or temporary plugging within the segment when injecting 50～100 m3 of acid. Based on these research results, a long horizontal well fixed-point diversion acid fracturing technique is developed and applied to five long horizontal wells, resulting in an average unobstructed flow rate of 235×10⁴ m³/d, which represents a 63.2% increase compared to the previous period.

Key words: Leikoupo Formation of western Sichuan, long horizontal well, fixed-point diversion acid fracturing, acid placement profile, temporary plugging timing