With the increasing demand for oil and gas resources in the world, the development of oil and gas fields is gradually developing in depth. In some famous oilfields at home and abroad, the vertical well depth has exceeded 9000m, the formation pressure has exceeded 140MPa, and the formation temperature has exceeded 200 ℃, which has reached the level of ultra-high pressure and high temperature drilling and completion. The continuous emergence of high pressure and high temperature, ultra-high pressure and high temperature wells makes exploration and development more difficult and drilling and completion problems more obvious. The most prominent problems are that the depth of the well is too large, the length of the string is very large, and the tensile load of the wellhead hanger is very large, which puts forward higher requirements for the wellhead equipment and the cracking sensitivity of the string at the wellhead. In addition, due to the high pressure and high temperature, the ultra-high pressure and high temperature wells generally contain CO2 and H2S. It is urgent to use high-strength corrosion-resistant oil pipe material under harsh bottom hole temperature, pressure and corrosion conditions.
Titanium alloy has high specific strength, good high temperature mechanical properties and strong corrosion resistance, which makes it a new material in the 21st century. Since the 1980s, titanium alloy has been used abroad in the manufacture of casing, tubing and some downhole tools for some high-pressure, high-temperature and ultra-high-pressure hot sour oil and gas wells.