Geology-engineering integration to improve drilling speed and safety in ultra-deep clastic reservoirs of the Qiulitage structural belt

The Qiulitage structural belt in Tarim Basin has a large reservoir burial depth and complex geological conditions. Challenges such as ultra-depth, high temperature, high pressure and high stress lead to significant problems related to well control safety and project efficiency. To solve these key technical issues that set barriers to the process of exploration and development, a drilling technology process via the integration of geology and engineering was established with geomechanics as the bridge. An integrated key drilling engineering technology was formed for improving the drilling speed and safety of ultra-deep wells, including well location optimization, well trajectory optimization, formation pressure prediction before drilling, stratum drillability evaluation, and bit and speed-up tool design and optimization. Combined with the seismic data, logging data, structural characteristics, and lithology distribution characteristics, a rock mechanics data volume related to the three-dimensional drilling resistance characteristics of the block was established for the first time. The longitudinal and lateral heterogeneities were quantitatively characterized, providing a basis for bit design, improvement and optimization. During the drilling process, the geomechanical model was corrected in time according to the actual drilling information, and the drilling "three pressures" data were updated in real time to support the dynamic adjustment of drilling parameters. Through field practice, the average drilling complexity rate was reduced from 18% to 4.6%, and the drilling cycle at 8,500 m depth was reduced from 326 days to 257 days, which comprised significant improvements compared to the vertical wells deployed in the early stage without considering geology-engineering integration.