Key Techniques of Drilling Penetration Rate Improvement in Ultra-Deep Well Chuanshen-1

Reservoirs of Well Chuanshen-1 drilling through can be characterized by large burial depth, strong abrasiveness of the continent strata, poor drillability, slow penetration rate of large diameter boreholes, as well as wellbore quality control. To fully investigate these problems, the following drilling techniques were applied optimally based on the stratigraphic and lithological characteristics of Well Chuanshen-1. The techniques include gas and foam drilling to significantly increase the ROP. Also, it included a newly developed foam system for hydration swelling inhibition of mudstone to effectively solve the problems of water production in the upper large diameter section, and also wellbore instability with insufficient cuttings carrying capacity. In addition, combination of rotary percussion drilling, PDC bit, and high-speed screw techniques greatly improved drilling efficiency in drilling through high-abrasive strata. In addition, the study sought to control the pre-bending dynamic deviation and to optimize drilling parameters using a high-efficiency PDC drill bit. The application results show that drilling techniques of the ultra-deep Well Chuanshen-1 effectively alleviate the drilling difficulties from complex formations. The key technologies for ultra-deep well drilling were formed on the basis of these techniques effectively applied in Well Chuanshen-1, and they solved or alleviated various drilling problems. The average ROP was increased to 2.11 m/h, and the drilling cycle was shortened to 475 days, and achieved favorable field application results. The studies suggest that the effective implementation of this technology can provide technical reference in ultra-deep well drilling in the future.