The degree of shale oil and gas enrichment and rock brittleness are key to the successful development of shale oil and gas in North America; however

in addition to the above factors

the high in-situ stresses in a complex geological structure also serve as a main factor hindering the effective development of marine shale gas in the Sichuan Basin.This study focuses on explaining the mechanism of hydraulic fracture propagation under complex and high in-situ stresses and demonstrating the impact of unfavorable in-situ stress conditions on fracturing effectiveness.The results show that shale reservoirs in the Sichuan Basin have higher minimum principal stresses

causing very high formation breakdown pressures.Through theoretical analysis and case study

the optimized design of drilling and completion is proposed

including horizontal well drilling direction

wellbore trajectory

and selection of hydraulic fracturing intervals.Recommendations for drilling and completion of the Fuling

Weirong

and Weiyuan shale gas fields are proposed based on the various in-situ stresses in different areas of the Sichuan Basin.