This paper systematically discusses the research progress of the deep and ultra-deep drilling technology in both China and other countries，analyzes the challenges faced by the deep and ultra-deep drilling technology，and points out the future development direction. With the exploitation of hydrocarbon resources shifting toward deep and ultra-deep formations，drilling technology faces many challenges，such as high temperature and high pressure （HTHP），complex geological structure，and wellbore instability. In recent years，significant progress has been made in the casing program optimization，ultra-deep drilling rig equipment，drilling fluid technology，etc.，but there are still vital problems，such as HTHP tolerance，wellbore instability and severe lost circulation. The future development of the casing program optimization technology is oriented toward intelligence and refinement to improve the risk warning accuracy and the dynamic adjustment ability of the casing program design. The rig equipment and key tools will focus on automation and intelligent upgrading to improve their tolerance of temperature and pressure and reliability. The drilling fluid technology needs to be further studied in terms of water- and oil- based drilling fluid systems tolerant of high temperature and high salinity and lost circulation control and plugging. These technological breakthroughs are expected to provide solid support for the efficient development of deep oil and gas resources.
