Jiaoye 197-4HF was a three-section long reach horizontal well drilled from the No.197 platform in the Fuling Pingqiao Shale Gas Field. The long horizontal section of the well was located in the shale member of Longmaxi Formation in Silurian. Great challenges were faced in drilling: (1) It was easy to form cuttings beds over the long horizontal section with high torque friction; (2) The shale was easy to hydrate and expand, resulting in wellbore instability; (3) Micro-fissures were developed in shale formation, leading to large loss of drilling fluids. In order to ensure the normal drilling operation, the appropriate formulation of the oil-based drilling fluid was optimized through indoor comparative experiments in the early stage. Field application showed that the optimized drilling fluid formulation fully met the requirements of the field work, achieving safe and smooth completion of the third-section horizontal drilling.