The deep shale gas reservoir are high formation temperature and pore pressure in Sichuan Basin. Due to the unclear geomechanical characteristics of the reservoir, a large number of accidents occurred during the drilling operation. At the same time, the wellbore instability and frequent adjustment trajectory cause long drilling cycle, low drilling efficiency, and high drilling operation cost. To solve the above problems, the drilling mud weight is optimized based on the three-dimensional geomechanical research and by establishing the pore pressure, collapse pressure and fracture pressure (leakage pressure) models. The key technology of reducing drilling mud weight are used to significantly reduce the drilling mud loss. Field application shows that the mud weight is reduced from 2.15 g/cm3 to 1.87 g/cm3, the average ROP increased by 44.1% from 8.4 m/h to 12.1 m/h, the average drilling operation cycle decreased by 40.7% from 54.2 days to 32.1 days, and the drilling performance and efficiency are significantly improved. The fine 3D geomechanical modeling technology has great promotion and reference significance for the performance and efficiency improvement of the deep shale gas horizontal well drilling operation in China.

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