Abstract: Faced with well drilling and completion technical challenges in the fields of deep formations, deepwater, unconventional resources, and mature oilfields, China has developed a series of major equipment, tools, instruments, and working fluids with independent intellectual property rights during the 14^th Five–Year Plan period. The integrated technical system has been established, including drilling and completion technologies for 10000-meter ultra-deep wells represented by “15000-meter automated drilling rig, high-temperature resistant downhole motor tools and efficient PDC bits, and 240 °C high-temperature resistant wellbore working fluids”. The unconventional oil and gas horizontal well drilling technologies have been iteratively upgraded, which are represented by “domestic rotary geosteering system and one-trip drilling for long horizontal section”. The drilling technologies for sidetracking and multilateral wells represented by “small-radius horizontal well” in mature oil and gas fields have been innovated and promoted. Breakthroughs have been made in key technologies and equipment for offshore deepwater well drilling, such as “offshore drilling automatic feedback dynamic well control system and deepwater riser system”. The well drilling technologies for new energy and low-carbon business, represented by “U-shaped horizontal wells”, have been developed. The digitalization and intelligentization of well drilling operations have continuously improved, strongly supporting the increase in oil and gas reserves and production and enabling high-quality development. Looking ahead to the 15^th Five–Year Plan period, the domestic upstream sector faces increasing difficulties in achieving cost-effective development of remaining recoverable reserves and the large-scale utilization of newly proven reserves. It poses a series of new challenges for drilling technologies in promoting the increase in oil and gas reserves and production and the integrated development of new energy businesses. By adhering to the directions of intelligentization, greening, and integration, it is essential to accelerate research and development of intelligent well drilling technologies, iteratively upgrade drilling technologies for 10000-meter ultra-deep well and unconventional oil and gas horizontal well, research 5-level multilateral well drilling technologies, and accelerate breakthroughs in safe and efficient drilling technologies for 1,500-meter deepwater wells and high-temperature geothermal wells.

Key words: drilling and completion technology, deep and ultra-deep wells, horizontal well, offshore drilling, intelligent drilling